3810041 uk residential tower blocks demolish or refurbish the energy perspective

MSc Thesis

University of East LondonSchool of Computing and Technology

Docklands Campus4-6 University Way

LondonE16 2RD

Telephone: 0208 2233000

Graduate School of the EnvironmentCentre for Alternative Technology,

Machynlleth,Powys,

SY20 9AZTel: 01654 704968

James LivingstoneJanuary 2008

UK RESIDENTIALTOWER BLOCKS.

DEMOLISH ORREFURBISH?

THEENERGY PERSPECTIVE

AbstractHousing contributes almost a third of the UK’s greenhouse gas emissions. Acoherent strategy is needed to reduce these emissions from the existinghousing stock.

Mass redevelopment of housing in the 1950’s 60’s and 70’s delivered estatesof ‘non traditional’ dwellings. The consequent movement and disruption ofcommunities caused social problems, and the tower block came to symboliseall the worst aspects of design and build of the times.

The reputation of the tower block has been blighted in almost all respects.Beyond social issues, the tower block has come to be thought of as energyinefficient and considered the epitome of the ‘Hard to Treat Home’.

This thesis looks at whether this reputation is well founded and relevant today.It asks if tower blocks have a role in reducing greenhouse gas emissions fromthe UK housing stock, or if energy priorities will dictate that they should be firstin line for demolition and replacement by more efficient dwellings.

It seeks also to provide tools for tower block owners to use in makinginvestment decisions about their housing stock.

Architecture, build quality, and condition are looked at to see whether there isa design and structural basis for preserving tower blocks. Structural conditionis sometimes a spurious reason for demolition of tower blocks when social andestate management issues are really the problem.

Stock knowledge and analysis of UK housing is assessed, and the conclusionsreached that what is known about the stock is inadequate for current purpose,and that the analysis of that knowledge unfairly blights certain building typesincluding tower blocks.

Refurbishment case studies show the inconsistency in approach that towerblock owners have at the moment.

Thermal simulation is used to model energy use and heat losses in towerblocks under a variety of scenarios. Results indicate that, although costs canbe high because of the access equipment required to carry out works,form and layout of tower blocks are actually conducive to relatively simpleimprovements in insulation and glazing, that can make tower blocks veryenergy efficient dwellings.

Calculations of embodied energy in demolition, refurbishment andreplacement dwellings reflect well on the lifetime energy use of a refurbishedtower block when compared with an energy efficient new dwelling.

Acknowledgements

I am very grateful to:

- Melissa Taylor, my tutor for this project, for general support and hercomments on the proposal and drafts.

- Damian Randle, and Mike Thompson for their support throughout the MSccourse.

- Anthony Dickins and Prija of Wates Construction Limited who were verygenerous with their time discussing and demonstrating the work at the LittleVenice refurbishment project in Westminster.

- Architects Kemp, Muir, Wealleans for further information about the LittleVenice project.

- Staff of The Apollo Group working on the refurbishment of Peregrine andKestrel Houses in Islington who went out of their way to show me round theproject with little notice.

- Graeme and Steven Henn of Islington Energy Centre for their time discussingthe energy strategy at Islington BC, and in particular the proposed installationof a wind turbine on Kestrel House.

- Chris Goodings at Solar Energy Alliance, for further discussions about theproposed wind turbine on Kestrel House.

- Graham Hill, David Green, and Andrew Chambers at Norwich City Councilfor discussion, copies of plans and access to Normandie Tower in Norwich.

- The Zero Carbon Britain project, the production of which coexisted with thethesis and encouraged my research into energy use and carbon emissions inbuildings.

- Andrew Holland, energy consultant, for fuel use figures for Winchester TowerNorwich.

- Duncan Josh and Jamie Bull for support and comment during the work.

- Pedro for his helpful comments on Modernism

- My partner Nicci for proof reading, supporting me and tolerating an unhealthylevel of interest in tower blocks for 6 months.

James Livingstone. Norfolk. January 2008

Contents

Abbreviations and Glossary

Abstract

1. Introduction 1

2. Literature Review 4

3.1. Understanding High Rise Buildings - History and Architecture 9

3.2. Understanding High Rise Buildings - Construction 17

3.3. Understanding High Rise Buildings - Condition 26

4. Environmental, Social and Legislative Issues 33

5. Classification and Comparison 39

6. Case Studies 47

7. Analysis of Heat Loads in High Rise Residential Buildings 66

8. Improvements to Thermal Performance - Potentials andPracticalities 77

9. The Environmental Impact of Demolition, Replacement andRefurbishment of High Rise Blocks 86

10. Summary and Conclusions 96

Appendices 100

Bibliography 105

Pictures and TablesFigure 1 The Bahrein Trade Centre (eso-news) ............................................... 8Figure 2: The Modern tower block ................................................................... 9Figure 3 : Unite D’habitation ( Photograph:Great buildings on line’) ............... 11Table 1 Post war Multi-storey Approvals and Starts...................................... 13Figure 4 : Expressions of Modern frame construction (via .Glendenning and

Muthesius)............................................................................................... 17Figure 5: Column and Beam Construction..................................................... 19Aylmer Tower in Norwich is an example of a column and Beam type

construction with brick in- fill panels. Post and beams, which are cast first,can be seen clearly in the photograph..................................................... 19

Figure 6: Butterfield Court in Dudley is an example of Box frame construction................................................................................................................ 19

Figure 7: Normandie Tower in Norwich is a Wimpey ‘No fines’ concrete block................................................................................................................ 20

Figure 8: Stephenson Tower in Birmingham is an example of LPS construction................................................................................................................ 20

Table 3 : Bison Wall external wall construction.............................................. 21Table 4: Bison Wall thermal characteristics results......................................... 22Table 5 : Recorded Insulation thickness for LPS type blocks ......................... 22Table 6: Cavity Wall Thermal Characteristics ................................................ 23Table 7: ‘No fines’ Concrete Thermal Characteristics ..................................... 23Table 8 : Typical thermal bridging components.............................................. 23

Figure 9: The Collapse of Ronan Point ( Photograph BBC)............................. 26Table 9 Indicative estimates for external repair costs to high rise blocks....... 30Table 10: Estimated Costs for Decent Homes Improvements ...................... 31Table 11: Total UK domestic energy consumption by end use (DCLG 2007) . 35Table 12: Growth in Total UK domestic energy consumption by end use (DTI,

2005) ....................................................................................................... 36Table 13 : Stock Profile (EHCS 2005)............................................................ 42Table 14: Condition of Homes (EHCS 2005) ................................................ 43Table 15: Condition of Homes Extracts from ECHS (EHCS 2005) ............... 44Table 16: heating costs and carbon dioxide emissions by dwelling type ....... 45Table 17: Glastonbury House basic information ............................................ 49Table 18: Glastonbury House. Key (predicted) performance data ................ 49Figure 10 : Glastonbury House proposal (Image : Cole Thompson Anders

Architects. ) ............................................................................................. 50Table 19: Makartstrasse Flats : basic information........................................... 52Table 20: Makartstrasse Flats. Post Occupancy Costs, Energy and Carbon

performance. ........................................................................................... 52Figure 11 : ...................................................................................................... 53Makartstrasse Flats before the refurbishment programme ............................. 53Figure 12: ....................................................................................................... 53Makartstrasse Flats after the refurbishment programme ................................ 53Information on this project came from Euroace. ............................................. 54Table 21 : Ozolciema iela 46/3, basic information .......................................... 54Table 22: Ozolciema iela 46/3. Cost, Energy and Carbon Performance........ 54Figure 13: Ozolciema iela 46/3 (Photograph Euroace).................................. 54Table 23: Little Venice Towers - basic information ......................................... 56

Table 24: Little Venice Towers . Cost Energy and Carbon Performance......... 56Figure 14: Polesworth House before refurbishment as the scaffolding is being

erected .................................................................................................... 58Figure 15: Wilmcote House after refurbishment with the scaffold being

dismantled............................................................................................... 58Figure 16: Over cladding and insulation detail on Little Venice project.......... 58Table 25: Kestrel and Peregrine Houses – basics .......................................... 59Table 26: Kestrel and Peregrine Houses. Cost, Energy and Carbon

performance ............................................................................................ 59Table 27: Wind turbine feasibility figures ....................................................... 60Figure 17: Kestrel House, Islington , soon to be home to a wind turbine........ 60Table 28: Six Towers Norwich – basics.......................................................... 62Table 29: Six Towers Norwich. Cost, Energy and Carbon performance ........ 62Figure 18: Normandie Tower IES Model......................................................... 69Figure 19: Normandie Tower Photograph....................................................... 69Table 30: IES VE Analysis of Boiler loads for Normandie Tower –(Whole

Block) ...................................................................................................... 71Table 31: Flat by flat results of IES.VE analysis ............................................. 72Table 32: Comparison of heat loads for flat and same construction bungalow.

................................................................................................................ 73Table 33: Actual and IES simulation figures for whole block boiler loads ...... 74Table 34 : Projected savings in cost of oil (per annum) from insulation

measures ................................................................................................ 75Figure 20: Aluminium over cladding at Little Venice has dramatically improved

the look of the blocks............................................................................... 78Figure 21: The corrugated concrete at Kestrel House has been expertly

repaired. .................................................................................................. 79Figure 22 : Detailing for cladding installation .................................................. 79Table 35: How Orientation and Tilt affect Photovoltaic Electricity Generation

Potential .................................................................................................. 83Table 36: Calculation of Mass. Embodied Energy and Embodied Carbon in

Normandie Tower .................................................................................... 89Table 37: Embodied Energy of new buildings (ECI 2007 p1)......................... 90Table 38: Calculating the embodied energy of insulated cladding .................. 91Table 39: Calculating the embodied energy of new windows ......................... 91Table 40: Benchmark figures for energy use for space heating from hot water

................................................................................................................ 92Figure 23: PassivHaus and refurbished flat. Lifetime energy use compared93Table 41: Examples of development densities................................................ 94Table 42: Normandie and Winchester Towers , Norwich. Existing

Construction details............................................................................... 101Figure 24: Ground Floor Plan of Winchester Tower...................................... 102Table 43: Tower Block modelled variables for IES VE simulations ............... 103Table 44: Oil consumption for Winchester Tower, Norwich. .......................... 104

Abbreviations and Glossary

BRE: Building Research EstablishmentBredem: Building Research Establishment Domestic Energy Model

Bredem is the name given to a family of simple but reliable energycalculation procedures for dwellings. It was first developed in the early1980s and, as a result of continuous testing and development, it hasbecome very widely used. (BRE 2007)

CERT : Carbon Emissions Reduction Target 2008-2011.This is the name given to the obligation on energy suppliers to supportrenewable energy sources, previously referred to as the EnergyEfficiency Commitment (EEC). The government proposes to double thelevel of the present EEC with a continuing focus on low incomeconsumers.

CO2 : Carbon DioxideCHP : Combined Heat and Power .

This term normally applies to the local generation of electricity, the by-product of which (heat) is supplied to local homes through a districtheating distribution network.

Cibse: Chartered Institute of Building Surveying EngineersCSE: Centre for Sustainable Energy.

An independent charity founded in 1979 established to seek andpromote energy solutions for individuals and communities.

DH: Decent Homes:The Decent Homes Programme is a government initiative aimed atbringing all houses in the rented sector up to a standard where they are‘warm, weather proof and having modern facilities’. (DCLG 2007) Inreality, the thermal comfort criteria for Decent Homes are so low as tohave little impact on works programmes and improving thermalefficiency of buildings.

Defra: Department of Environment Food and Rural AffairsDTI: Department of Trade and IndustryECI: Environmental Change Institute

Centre for research, outreach and graduate studies in environmentalchange and management at Oxford Brookes University. Authors of the40% house.

EEC: Energy Efficiency CommitmentThe obligation on energy suppliers to support renewable energysources, soon to become CERT.

Euroace: The European Alliance of Companies for Energy Efficiency inBuildings.

Organisation set up in 1998 by 20 large European companies, allinvolved in the business of energy efficiency in buildings.

GHG : Greenhouse gasesHTTH: Hard To Treat Homes.

HTTH are generally defined as dwellings which have no loft or cavitywhere insulation can be installed. The term is often used moregenerically.

HECA: Home Energy Conservation ActThe Home Energy Conservation Act 1995 (HECA) requires every UKlocal authority with housing responsibilities to prepare, publish andsubmit to the Secretary of State an energy conservation reportidentifying practicable and cost-effective measures to significantlyimprove the energy efficiency of all residential accommodation in theirarea , and report on progress made in implementing the measures.(Defra 2008)

IES VE : Integrated Environmental Solutions Virtual EnvironmentBuilding simulation computer programme.

Insulation types :Thermosetting. Includes Polyisocanurates, phenolic foams andpolyurethaneThermoplastic Extruded and expanded polystyreneWool types

KWh: Kilowatt hoursLA: Local AuthorityMWh : Megawatt HourNon-traditional construction:

This broad definition describes construction types built between 1919and 1980 that were prefabricated or system built. They amount to aboutone million in number and include a variety of steel framed, concreteand timber framed buildings.(NCEH 2008)

NCEH : National Centre for Excellence in HousingNo Fines Concrete:

Concrete in which a lower proportion than usual of sand and other finesare included. This produces aerated concrete of lighter weight, lessstrength and marginally improved thermal performance suitable for nonload bearing walls. These were pioneered and used most extensivelyby Wimpey in post war flats and houses.

NSTBI: National Sustainable Tower Blocks InitiativePassivhaus:

The term 'PassivHaus' refers to a specific construction standard forresidential buildings which have excellent comfort conditions in bothwinter and summer.PassivHaus dwellings typically achieve an energy saving of 90%compared to existing housing. The standard was developed in Germanyand there are to date at least 6000 dwellings built to the standard.(PassivHaus UK 2008)

RCEP: Royal Commission on Environmental PollutionRetscreen:

Retscreen is a Canadian renewable energy assessment computerprogramme that is widely used to establish potentials of renewableenergy sources in different situations.(Retscreen 2007)

ROC: Renewable Obligations Certificate.This is the certificate issued to producers of renewable electricity. OneROC is issued for every megawatt of eligible renewable powerproduced. Renewables obligation orders are served on electricitygenerators to incentivise the move from fossil fuel generation togeneration from renewable sources . The Orders place an obligation on

licensed electricity generators to source an increasing proportion ofelectricity from renewable sources.ROCs have value and are traded from those who generate moreelectricity from renewables than they need to fulfil their obligations, tothose who generate less than they need. (ofgem 2008)

RSL: Registered Social LandlordSAP: Standard Assessment Procedure

SAP is the Government’s Procedure for energy rating of dwellings. It isused to demonstrate compliance with building regulations and toprovide energy ratings for dwellings. (BRE 2008)

U Value:‘U- value’ is the rate of heat flow over unit area of any buildingcomponent calculated through unit overall temperature differencebetween both sides of the component. (Clear 2008)

Warm Front:The Warm Front Scheme addresses fuel poverty issues by awardinggrants for the installation of heating or insulation to those in receipt ofbenefits or credits. (Www.warmfront.co.uk)

ZCB: Zero Carbon Britain

James Livingstone 1

1. Introduction

Background

Europe is facing crises in the climate, energy security and housing.

With over a quarter of carbon dioxide emissions in the UK coming fromexisting housing, and with housing in short supply and poor condition, sometough decisions are needed.

Why Tower Blocks?

High rise dwellings number some 300,000 in England and 36,000,000 inEurope, representing about 1.5% and 15% of the housing stock respectively.(English House Condition Survey 2008, Euroace 2008)

High rise dwellings are not just numerically significant in themselves. Theyalso act as an archetype of construction for a lot of the housing buildingsconstructed between 1950 and 1980. There are for example, a further2,677,000 medium rise purpose built flats in the England having similarconstruction details as high rise. (English House Condition Survey 2008)

Further, they have a symbolic importance, initially of post war architecturaloptimism, and later of social breakdown and urban deprivation. They stand talland significant in the urban ‘skyscape’ of all Europe’s major cities.

However, society has suffered from problems arising from the vast socialexperiment that post war housing became.

Because of these problems, high rise buildings are still being demolished at anunprecedented rate, this despite signs of a renewed interest in their potential.

In the current rush to redevelop post war estates and build new communities,there is a very real risk of repeating the mistakes of the past, when goodbuildings were wiped away with the bad in widespread demolition andredevelopment schemes that were based on social and political imperatives,rather than on careful assessment of the stock.

Energy Standards

Legislation and guidance for new housing is being introduced to ensure thatnew dwellings at least, are built to high energy efficiency standards.

James Livingstone 2

Laudable as this is, it has limited impact on carbon dioxide emissions from theUK housing stock, because, at present rates of construction and demolition,over 90% of UK housing in 50 years time will be the buildings that exist now.1

There is no matching legislation and guidance for existing housing. Energyimprovement works to these have so far focused on the ‘quick hits’ of loft andcavity wall insulation. However, there is a growing realisation that this does notreach enough of the stock, and cavity wall insulation in itself rarely producesthe improvements in the thermal performance of a building that are nowrequired.

There is little incentive, little information and little support for energy efficientapproaches to refurbishment, and where high rise blocks are beingrefurbished instead of being demolished, they are apparently being done withlittle recognition of the need for energy efficiency.

Should priorities change?

Content

This thesis therefore, aims to examine the environmental credentials of thehigh rise residential block to assess its potential in a world where energy usemust play a bigger part in decision making.

The limited amount of the previous work in this area is looked at in chaptertwo. This thesis attempts to go further. It tries to make specific contributions tothe decision making process about high rise buildings, by providing newperspectives and an energy model for building owners to apply to theirhousing investment decisions.

Local social circumstances will sometimes dictate the future of an estate, andthis is as it should be. Although it is not the business of this thesis to do anymore than to recognise that as a fact, it does try and look behind some of thepreconceptions arising from the perceptions of those problems. These arelooked at in some detail in chapter three.

For example, it is commonly thought that high rise blocks were ill conceivedand badly designed from the start. It is often said that tower blocks were badlybuilt and are falling down. If either contention were fundamentally true,investment of any sort would not be worthwhile. Construction science andtypes are examined to put these ideas to the test.

Chapter four looks in greater detail at the environmental and legislative contextin which the study is being done, and provides an introduction to the debateabout lifetime energy performance in new and refurbished buildings. Thiscontinues in chapter five with examination of the concept of ‘ hard to treat

1 Demolition rates currently at about 20,000 per year and new build at 180,000 per year. (CAT2007)

James Livingstone 3

homes’ and whether the labelling of high rise blocks as ‘hard to treat’ is corrector still relevant given the available evidence.

Case studies are not easily found, but several contractors, architects and localauthorities were good enough to give comprehensive access to someinteresting refurbishment projects, and these are looked at in detail in chaptersix, together with some secondary research downloaded from governmentsponsored, and commercial web sites. These provide an empirical base for thelater analysis.

Computer modelling is used in chapter seven to analyse the thermalperformance of a particular tower block, and to measure the effects of energyefficiency improvements on it. The modelled improvements are external wallinsulation and double glazing, as these two basic measures address the shellof the building where the heat losses to the majority of flats occur.

The practicalities of wall insulation and double glazing are addressed inchapter eight.

It is the generally accepted presumption of this thesis that insulation should bemaximised before power generation from renewables is considered, but inchapter nine, recognition is also given to the particular contributions thatdistrict heating, combined heat and power (CHP), and renewable technologiescan make to high rise dwellings.

Demolition and refurbishment are compared in the last chapter, in terms ofembodied energy, energy in use and land use.

The conclusion assesses the success of the project.

James Livingstone 4

2. Literature Review

This chapter looks at the most significant contributions to thestudy of sustainability of high rise dwellings. It aims to reviewwhat is written and to ensure that the thesis is adding to these –not duplicating them. It also acknowledges some of the mostimportant sources of background information for the thesis andlastly, looks at some of the contemporary thinking about high risebuildings.

‘Sustaining Towers’ Resource and Website

This website was researched and written by Prashant Kapoor of Price andMyers and published in 2004. It was set up by project partners, Price andMyers, Battle McCarthy, Architype, STBI and Franklin Andrews, and wasfunded by the Department of Trade and Industry.

It aims to:“........ facilitate the regeneration of the 3000+ residential high rise blocks in theUK with proposals for sustainable solutions integrating environmental, socialand economic criteria.”

The resource starts by putting the issues in context under the headings of:

• Background :Why refurbish?, history of tower blocks, present context, case studies.and ..

• Refurbishment Process:Consultation, funding and decanting.

It takes a broad brush approach to a wide range of sustainability issues andpresents the issues as ‘design options’ for:

• Building roof, building facade, entrance and security, lifts, lobby andcorridors, flat layout , heating and hot water, electrical and IT, ventilation, watersupply, waste management, site and surroundings, landscape andenvironment, and tenants and management.

Of these headings, the building facade is the most relevant to this thesis so itis this that is looked at in more detail below to demonstrate the approach takenby the Sustaining Towers resource.

James Livingstone 5

‘Building facade’ identifies the various opportunities for improvement to thebuilding facade as:

• ‘Basic’ including over cladding, add thermal insulation, replace windows ,provide trickle vents , provide draft stripping.

• ‘Good’: provide solar shading, increase size of openings, enclose balconies.

• ‘Exemplary’ : Install photo voltaic cladding

For each of these ‘opportunities’, the possible methods, advantages anddisadvantages and potential unit costs are briefly described.

It provides a very good overview of the possibilities, illustrated with examplesand some technical detail.

The breadth of view that it takes is exciting, and it looks for opportunities (suchas constructing extra floors and growing plants up the walls) that push theboundaries back a bit from conventional thinking. A realm of possibilitiesoutside the normal scope of Local Authority (LA) or Registered Social Landlord(RSL) work is presented.

It is perhaps this ambition that is also the limitation of the site, for whilst theideas are great, the opportunities for carrying out a lot of these improvementsare in reality only the preserve of the private sector.

Case:Berkeley Homes have built extra stories on the fully privatised Aragon Tower in eastLondon, and this has helped finance the improvements to the rest of the block.

Few would argue however, that the change in tenure from social tenant to private owner isas important a factor in ‘turning round’ this once dilapidated block, as is the investment insustainable physical improvements to it.

The LAs and RSLs that are the usual owners of these buildings are rarely in afinancial position to consider many of the options presented here. Officersoften have to fight for sufficient funds to carry out basic repairs let alone forimprovements.

In reality, building owners faced with social deprivation, and structuraldilapidation and very limited budgets in an unsupportive political environment,have to make hard and often unacceptable choices. If they are given theopportunity to invest in their high rise blocks it is often only the basics that theywill be able looking at.

The site describes itself in part as a tool kit for building owners, but falls shortof the real detail to enable financial cases to be made for any of the options. Itis possible to estimate some costs, but no detailed information of the benefitsis given.

James Livingstone 6

Nevertheless, it is a useful resource that may have inspired some.

In terms of this thesis, ‘Sustaining Towers’ has been drawn on only in respectof using some of the budget figures for energy improvements as comparators.

Leads to some of the examples given on the site have also been followed

National Sustainable Tower Blocks Initiative

The National Sustainable Tower Blocks Initiative (NSTBI) was set up to:

“.... address the need for a coherent strategy to improve the social and environmentalsustainability of Britain's tower blocks.”

The main product of the initiative, apart from co-sponsorship of the SustainingTowers resource above, seems to be the 2000 report ‘Streets in the Sky’ (Galeand Church 2000) which introduces the subject and identifies the needs andmeans of moving towards ‘sustainable’ tower blocks under the followingheadings:

• ‘Tower Blocks matter’ introduces the subject and spells out the aims of theNSTBI which include demonstration, disseminating good practice, influencingpolicy, providing guidance to tenants.

• ‘Tower Blocks – the challenge’ identifies the perceived and actual problemswith tower blocks and the associated funding and management issues.

• ‘Making a start’ proposes new ways of thinking and identifies opportunitiesand potential benefits of tower blocks.

• ‘Making it happen’ proposes ways of dealing with what it sees as the keyissue of funding, building communities, security, and management, all in thecontext of urban regeneration.

Whilst there is some brief discussion of energy, particularly in relation to wastewhen tower blocks are demolished, building ‘sustainable communities’ is thebasis of this initiative rather than energy and the environment.

The NSTBI appear to have been mostly inactive since 2000.

Euroace

The European Alliance of Companies for Energy Efficiency in Buildings(Euroace) was set up in 1998 by 20 large European companies, all involved inthe business of energy efficiency in buildings.

The information relevant to high rise dwellings is included in a publisheddocument entitled ‘Changing the View ‘ (subtitled Energy Efficiency in theRefurbishment of High Rise Buildings).

James Livingstone 7

It divides Europe into climatic zones, identifies the numbers of high risedwellings (36 million – or one in six households!), identifies the potentialimprovements in terms of process (insulation, window improvement andservices improvements) and in terms of carbon saving, and makesrecommendations for policy and research.

This is a commercial site and its primary aim is to lobby, but there is usefulinformation particularly in respect of basic data and for the examples, some ofwhich are used later in the thesis.

Other Resources

It is important also to acknowledge the principal resources used forbackground, context and technical understanding.

For historical and architectural context, Glendenning and Muthesius’ book TheTower Block. Modern Public Housing in England Scotland and NorthernIreland, was important. The website ‘From Here to Modernity’ was also usefulfor further information this area.

For technical understanding and some early case studies, Building ResearchEstablishment (BRE) reports were well used.

For thermal simulation, the Integrated Energy Solutions Virtual Environment(IES VE ) software was used. IES VE is among five widely used simulationprogrammes in the UK. It has been tested using ANSI/ASHRAE Standard 140-2001 building energy simulation software accreditation tests and is approvedby The Chartered Institute of Building Services Engineers for use under theirLow Carbon Consultant Programme. It is also approved for use for SAPcalculations and for compliance with part L2 of the Building Regulations.

For U Value calculations ‘Build Desk’ software was used. This software isapproved for use in calculations for SAP for Part L of the Building Regulations.

Other resources are referenced in the bibliography.

Contemporary thinking

Finally, it is worth giving space here to some of the recent renewed interest innew high rise buildings, both residential and office based. Land pressure incities and shifts in planning perspectives, have meant that high rise buildingsnow being built in all major cities once again.

There is surprise among many at this development, partly because of theassociations that high rise residential has with urban deprivation, and partlybecause many see new high rise as unsustainable.

James Livingstone 8

It is not a part of this thesis to consider these issues in any depth, but it notesthe following in the interest of shedding light on some of the later discussions:

Sue Roaf (Roaf et al 2005 p240 - p265), argues strongly against new high rise,on the grounds of cost, carbon footprint, psychological effects and shading.

She welcomes the potential opportunities for wind generators, transparentphotovoltaics and geothermal piles in high rise developments, but highlightstheir limitations because of the poor ratio of roof to floor space. She alsorecognises that extra energy demands are placed on high rise dwellingsbecause of lifts, wind pressure, thermal stratification, solar gains andmaintenance inputs.

Having said all this, the integration of renewables - sometimes in spectacularfashion, can teach useful lessons about the use of this type of technology inour existing buildings, and breakthroughs can be made.

These projects go ahead for reasons of status, architectural experiment andland pressure. What they bring us may be folly, but the level of investment inresearch and development is important in informing the work that is done onmore modest projects.

Case :The Bahrein Trade Centre (left )has three 29 metrediameter integrated wind turbines producing 1.3GWh electricity per year.

The Burj al-Taqa in Dubai has a 200 foot verticalaxis wind turbine and 244,000 square feet of linkedsolar panels.

Figure 1 The Bahrein Trade Centre (eso-news)

James Livingstone 9

3.1. Understanding HighRise Buildings -History andArchitecture

This section looks at the development of the residential towerblock in the UK to put it into its historical and architecturalcontext.

It is included in order to explain and examine the philosophy andquality of the original concepts for high rise dwellings, and toreach round some of the current stereotypical views of them.

Figure 2: The Modern tower block

James Livingstone 10

Introduction

To understand the development of the tower block requires the study ofarchitecture (Modernism, Gropius, Le Corbusier and the Chicago School),technological developments in building materials, and the politics andsociology of post war Britain.

It is a common misconception to think of flats as a 20th century invention. Flatswere commonplace in 19th century cities.

“Tenements had existed for centuries. Four to six storey blocks had been thepredominant urban form of housing form the middle of the 19th century.”(Glendenning and Muthesius 1993 p 24)

However, although people have long been familiar with living in low rise flats, itis true that the high and medium rise blocks that are so much a feature of oururban landscape today, are largely a product of the special conditions of themid 20th century.

Architecture and Technology

High rise blocks were an expression of Modernism, which arose, in large part,as a reaction against the perceived over decoration of Art Nouveau and Deco,and the decadence of the Dada and Surrealist movements of the early part ofthe 20th century.

‘Modern’ architecture rejected the past as a source of inspiration andembraced new materials and technology as source of design inspiration. Itwas an expression of design by function and material capacity rather than byvisual expression and an attraction to detail and ornamentation.

Le Corbusier, Walter Gropius and Mies Van der Rohe were leading pioneers ofModernist architecture and they defined the philosophy behind the Modernistdream of a better world for all.

These were people of intellect and ambition who were trying to define a visionof architecture in which buildings worked for people. They felt able to riseabove the limitations of earlier architecture by the freedom afforded to them bythe availability of the new materials of steel and concrete.

In 1921 Le Corbusier described a house as “a machine for living in”, thatshould have.... :

“ the purity of form of a well designed machine”.(From Here to Modernity)

The aspiration for good lighting was a prime driver and as Glendenning andMuthesius point out ...


“ An increase in height will always, for a given density of population, improvelighting conditions” (Glendenning and Muthesius 1993 p53)

Walter Gropius vocalised the desire to move away from the darkness andsqualor of what were now seen as primitive Victorian slums:

“ ... all dwellings should command a clear view of the sky over the broadexpanses of grass ... instead of the ground floor windows looking onto blankwalls or onto sunless courtyards” (Glendenning and Muthesius 1993 p45) .

In the 1920’s Le Corbusier developed the ‘Dom-ino’ system. This together withthe ‘Chicago frame’ gave rise to two of the most important ideas in modernistarchitecture. The birth of the framed building led to a freedom of design byallowing a design separation of the floor plan and elevation, from the structure.It also introduced mass, and off site production into building.

One of the most important driving concepts of this architecture was one ofcreating ‘communities in the sky’ and this aspiration led to the predominantpre-war high rise form – the slab type blocks often known as Zeilenbon blocks.These were characterised by being low to medium rise and were generallyassociated with deck/ balcony access.

The ultimate expression of this is the‘Unite d’habitation’ – or the MarseilleBuilding1. This building includes ashopping centre on seventh floor andcommunity recreational space on theroof.

“1600 people form a manageably sizedcommunity that gives the benefits of bothindividual privacy and collectiveparticipation.” (Jencks 2000 p258)

This continues to be a very successfulbuilding, with high demand.

Figure 3 : Unite D’habitation ( Photograph:Great buildings on line’)

Slab blocks however, had the disadvantage, when built close together, ofshading each other and provided only relatively low density environments.

The aspiration for height was driven partly by the need to achieve higherdensities, but also (as is still seen today) by the architect’s ambition to createarchitecturally imposing buildings. (This aspiration was perhaps the first tocompromise the design premise of building serving the occupant).

1 Le Corbusier. Completed 1954


This led to the development of the ‘point’ block, early examples of which weregenerally built on green field sites such as those at Roehampton in London.

Along side this architectural and social ambition, were the development ofstructural engineering principles, the understanding of reinforced concrete andthe rapid development of industrial techniques for mass production.

In addition, the concept of the ‘U’ Value was introduced at this time and wasfirst seen in the Housing Manual of 1944. According to Glendenning andMuthesius...

“.. the thermal properties of all kinds of external walls were minutelyinvestigated...” (Glendenning and Muthesius 1993 p80)

Politics and Social Conditions

It is easy to forget that up until the 1950s only a very small proportion ofhousing had even the most basic facilities. Running water was often at the endof the road and ‘in house’ bathrooms, electricity and heating were unusual.

By 1945 the social fabric of society had been overwhelmed by two world warswhich had diverted all investment from domestic infrastructure. The buildingsthat had survived the war were worn out and in a poor state of repair.

Housing became the most important public and political expression ofrebuilding the country after the Second World War. ‘Homes fit for heroes’became an important banner for the post war labour government which, in theend committed itself to achieving by :

“ brute force house building” (Glendenning and Muthesius 1993 p312)

Town planning became an important area of study and debate. In 1944, theGreater London Plan looked back at inter-war housing planning with dismay:

“ London indeed can take no pride in the bulk of the 600,000 houses that werebuilt on her ever expanding outskirts between the wars. What would ourfeelings be if were thought that the scheme of decentralisation proposed inthis plan were destined to impose on the still vacant land a mass of similarhouses similarly disposed, during the next decade? Would a repetition ofLondon’s sprawl be something that we should want to show our allies as ourcontribution to remaking the world?”(The Greater London Plan 1944: Sect 476 – 490)

Whether to build flats or houses was thus the subject of much heated debate.In the end however, rebuilding more small houses was felt to be tantamount torebuilding the slums they were trying to replace.

The provision of facilities was also thought about in great detail. Despite whatmight appear inadequate provision now, these new housing units were a hugeimprovement in terms of space and ‘basic’ facilities over those that they


replaced. Each member of a family had a room of their own, and by the early1960’s there was more or less universal application of the ‘Parker Morris ‘standards which defined minimum provision for spaces for new dwellings.Where individual provision was not thought to be feasible, communal laundriesand drying areas played well to the idea of creating those ‘communities in thesky’.

And people at the time appear to have been very happy with their new homes:

“ Small wonder Mrs Gameroll likes her flat. When the rival claims for flatversus house arise for discussion she will no doubt agree that here at SpaGreen the Finsbury Borough Council have demonstrated to the full the manyadvantages ,- individual and communal – among which she includes herneighbours . “The people here are all so nice” she says.(Concrete Today 1951)

Reality sets in

“The optimism of Le Corbusier, Lubetkin, and Modernism's early champions,the belief that their new architecture would contribute to a better world for all,and the optimism of the post war welfare state which had striven to make thatvision real, were all swept away in a torrent of bad buildings and economiccrisis. The modernist dream, it seemed, was dead” (From Here to Modernity).

Between 1945 and 1969 4 million public sector dwellings were constructedand as the numbers of homes required continued to increase through the1950’s and1960’s several things happened.

Table 1 Post war Multi-storey Approvals and Starts

Date Number

Pre 1948 3212

1948 –1952 14170

1953-1957 31453

1958- 1962 77054

1963-1967 20047

1968-1978 65623

1972 0n 11119

Total 403108 flats 6544 blocks(Glendenning and Muthesius 1993 Appendix )

The quantity of houses built became more important than quality. As a result,some of the in situ construction was done on the cheap. The shortcuts tendedto be in the provision of services and communal areas, and this resulted inproblems with safety, lighting and landscaping.

The pressure to build meant that incentives were introduced to production.The 1956 Housing Act, for example, incentivised high rise building, regardlessof location and design, by paying a premium to councils for building blockshigher than five storeys.


Land shortages, labour shortages and materials shortages all encouraged amove towards high density system built housing.

The ability to build higher drove the architects and engineers to do just that.Technical and architectural challenges therefore sometimes overwhelmedgood design.

Eventually high rise residential work ceased to be of interest to avant-gardearchitects and design became the responsibility of the municipal architect, and,increasingly of the contractor. The construction process was therebyindustrialised and individual design was replaced by ‘off the peg’ systemsbuilds.

By the early sixties, the volume of building work had reached unmanageableproportions, resulting in labour shortages, over powerful unions, andallegations of impropriety over contract awards in Local Authorities.

Different cities embraced different methods in different ways according totaste, the extent of war damage, and the influence of individual builders in anarea. The really big medium rise slab developments were built in Scotland andSheffield with estates such as Sighthill, Red Road, Ardlew and Park Hill,whereas Midlands’ cities like Birmingham embraced the system built pointblock with greater enthusiasm.

The ideals of ‘Modern’ architecture were thus compromised by the speed andurgency of the house building boom, which at its peak in 1965, reached383,000 - about twice what it is today!

Demise and Rejection

As early as 1953, Alison and Peter Smithson were expressing doubts aboutthe social effects of modernist domestic architecture. They wrote...

"The short narrow street of the slum succeeds where spacious redevelopmentfrequently fails." (From Here to Modernity).

... and they responded by designing their own version of modernism with aconscious reversion to the early ideals of Le Corbusier and Gropius, and amore neighbourly reinterpretation of these ideals. Denys Lasdun did likewise.

Sheffield’s Park Hill estate was designed with these ideals and concerns inmind too, but this was not immune from the social problems that werebeginning to surface in these modern developments.

Although it was the architecture that took the blame, this was not principally afailure of design. It was a failure resulting from the corruption of the design bymass market interpretation, from the break up of communities, and perhaps,above all, from the under investment in management of these estates.


Despite that, by the early 1960’s the level of dissatisfaction with modernestates had generated so much criticism that Modernism as an architecturalphilosophy was effectively dead, and generally agreed to be a failure.

The final nail in the coffin of Modernism was driven home on the 16th May1968, when Mrs Ivy Hodge struck a match in her kitchen and blew out the sideof her 18th storey flat resulting in the collapse of one end of Ronan Point inEast London.

“It was modern architecture's Titanic, and spelled the end of the high-rise as aviable solution to the post-war housing crisis as well as plunging modernarchitecture and the architectural profession to a low level of public esteem”. (From Here to Modernity).

The result of this was to question the very structural integrity of high riseblocks, and encourage the anti Modernist lobby.

However, although the systematic dismantling of Ronan Point revealed someappalling workmanship in its assembly, subsequent survey of similar blocksdid not reveal any inherent structural problems, and there are no examples ofmajor failures anywhere else among tower blocks in this country.

Management failures however, were often presented as evidence that thestructure of the blocks were inherently defective, and this reputation haslargely remained, giving ‘justice’ to building owners wanting to hide theirfailure to manage tower blocks behind a programme of demolition andreplacement. This is looked at in greater detail later in this section.

The net result of this about turn on high rise living has been the systematicdestruction of large numbers of tower blocks, and many cities have seen theritual explosive demolition of the majority of them.

The emotive headlines of the Birmingham Mail on March 19th 2007 - as theyreported the demolition of Hamilton House, go a long way to illustrate thefeelings, and ingrained preconceptions about high rise living that prevail evennow in some quarters.

“ eyesore tower block bites the dust”

The article continues with:

” The demolition of the 24-storey building forms part of a multi-million poundregeneration project to bring council housing up to standard by 2010. ...... Itwas the 58th tower block removed by the council and the 25th to be downedby explosives. ...... Cabinet member for neighbourhoods Councillor MahboobHussein said: "I'm sure residents are delighted to see this tower blockdemolished."


Redemption

Not all high rise blocks were problematic however. In Aberdeen theyestablished a management and allocations model that worked, and theycontinued to build high rise until the mid 1980s.

And there are many signs now of a reappraisal of high rise blocks as housingand land shortages necessitate a rethink.

A lot of the worst blocks are gone, and although there is still a significantbacklog of repairs in social housing, a lot of investment has been made intosecurity and other environmental improvements. Landlords have also learnedhow to manage high modern estates better by improving security, encouragingtenants associations, and ensuring common areas are kept clean, safe andwell lit.

The ‘Right To Buy’ has created mixed tenure blocks, and in some cases entireblocks have been taken over by private developers, turning what were onceconsidered ‘squalid council flats’ into luxury apartments for young executives.Even some blocks that remain in our social housing stock such as TrellickTower in West London have apparently been redeemed, by a combination ofgood management by landlords and resident involvement. Trellick Tower isnow one of London’s fashionable addresses.

Conclusions:

This section concludes that Modern architecture was the productof a high minded and virtuous ideal that was corrupted in a madrush to build.

The Modernist movement behind the development of the high riseblock was a principled one in which the best examples produced(such as the Unite d’habitation) are still cherished and continue towork well.

It also concludes that high rise housing is not inherently bad, thatpublic perception is perhaps coloured by the inability of sociallandlords to manage their new responsibilities, and that thebeginnings of a long overdue reappraisal of the qualities of highdensity high rise living is now starting.


3.2. UnderstandingHigh Rise Buildings -Construction

3.2 looks at the way tower blocks were built and what constructioncharacteristics they consequently have. This informs laterdiscussions about condition, comfort and ‘hard to treat’ homes.Discussion concentrates on the walls, windows and a briefdescription of the heating to maintain focus on the thermal andenvironmental issues that are the focus of this work. Roof andground constructions are ignored as being of no special relevanceto the discussion about tower blocks.

Figure 4 : Expressions of Modern frame construction (via .Glendenning and

Muthesius)


Technology

Materials development and structural science largely determine the structuralevolution of the tower block.

The ‘Chicago frame’ and pre-war tower block design in the UK werepredominantly steel framed, with conventional in-fill panels of brick.Traditional brickwork was also occasionally used at this time, up to abouteleven storeys in height.

Significant improvements in reinforced concrete technology just after theSecond World war encouraged the development of cast in situ, and pre-castconcrete buildings. In the early 1950’s reinforced concrete frames with in-fillpanels predominated , later giving way to frame construction including‘crosswall’, ‘egg box’ and ‘box frames’.

At the same time, the concept of cladding came into its own. High risebuildings place special demands on their exposed components, so researchwas done into developing materials to incorporate qualities of weatherproofing,good looks, durability and insulation. Materials such as steel, aluminium,asbestos, wood, concrete and later, plastics were all developed in differentforms that would take on these qualities.

Exact construction information is hard to come by and is not often availablefrom design details, as a lot of high rise blocks were built under ‘design andbuild’ contracts and details were never recorded. A lot of the information hereis obtained from pre refurbishment survey details.

Four commonly defined types

The large majority of the 6544 buildings this thesis concerns itself with werebuilt between 1953 and 1978. During this period there were four main types ofhigh rise construction built. Within these four main types there are variationsbut essentially this is it:

Column and Beam,Box Frame,’No Fines’ ConcreteLarge Panel system.(LPS)

Column and Beam Construction

In this construction type, a framework of reinforced concrete columns andbeams are cast in situ. The floors are cast in situ concrete on the framework,the internal walls are generally constructed of lightweight aggregate blocks orbrickwork, and the external panels between the frame members are usuallybrick cavity walls.


Figure 5: Column and Beam Construction

Aylmer Tower in Norwich is an example of a columnand Beam type construction with brick in- fill panels.

Post and beams, which are cast first, can be seen

clearly in the photograph

(Photograph : Author )

Box Frame Construction

Box frame construction involves the in situ casting of reinforced concretewalls, which support the floor above. External walls are generally not loadbearing and are usually of cavity brick construction or pre-cast concretesections lifted into place.

Various proprietary box frame methods are recorded by the BRE (Glick andReeves 1996) such as Laidlaw-Thornton and MWM.

Figure 6: Butterfield Court in Dudley is an example

of Box frame construction

(Photograph : Skyscraper city )

No Fines Concrete Construction

‘No fines’ concrete is a concrete with a smaller proportion of sand than is usualin concrete. This results in a lightweight concrete with higher insulation values.It was widely used for housing in all forms, particularly by Wimpey.

In high rise blocks it was sometimes combined with the post and beamsystem, in order to reduce the load bearing on the ‘no fines’ concrete.

Floors were cast in situ high density concrete. External walls were generallydrylined internally and pebble dashed externally. (Williams and Ward 1991)


Figure 7: Normandie Tower in Norwich is a Wimpey‘No fines’ concrete block

(Photograph : Author )

Large Panel System (LPS) Construction

Large Panel Systems were a late development in the construction of high riseblocks, but soon became the most common, owing to the fact that the panelswere factory constructed, allowing for quick weather proof assembly on site.Reinforced concrete storey height panels for internal, external and spine wallsmake up the buildings, with the central services spine often being cast in situ,to provide a degree of rigidity to the structure.

Figure 8: Stephenson Tower in Birmingham is anexample of LPS construction

(Photograph : Skyscraper city )

Camus, Bison Wall frame and Taylor Woodrow Anglian (Larsen Neilson), wereperhaps the most widely applied systems, in which each floor was supportedby the load bearing walls directly beneath it. The wall and floor system fittedtogether in slots with overlaps on the horizontal, and straight joints on thevertical. These were bolted together and filled with dry pack mortar to securethe connections. (BRE 1985)


Thermal Characteristics.

Although this thesis looks briefly in the next section at the repair problemsthese constructions have in order to assess their longevity, the primary interesthere is in the thermal characteristics of these blocks.

There is scant good information on exactly how these blocks are constructed,but certain conclusions can be drawn from first hand observation (see Chapter 6,Case Studies) and from the available literature .

Walls:

Standards

For benchmarking and comparison purposes some standard wallconstructions their U values are recorded in Table 2 below.

Table 2 :Typical U values for wall constructions1

Wall Construction ( all plastered internally) Typical U Value

225mm solid brick ( e.g for Terraced house or cottage) 2.18 Wm2K

300mm solid slate wall 2.86 Wm2K

Typical brick cavity wall with no insulation 1.06 Wm2K

Typical brick cavity wall with 50mm fibreglass insulation 0.47Wm2K

2006 Building Regulations ( min elemental) standard Cavitywall

0.35 Wm2K

1 Calculated using Build Desk Programme

External wall types that predominate in the four types of high rise blocks are:

Sandwich wallsCavity wallsSolid concrete wallsThese are examined individually in the following sections.

Sandwich Walls

The best available sandwich wall construction details are from the BRE studyof Bison Wall Frame construction (Hotchkiss and Edwards 1998)

Table 3 : Bison Wall external wall construction

Bison Wall frame

Pre-cast reinforced concrete load bearing storey height sandwich panel comprising:

6 inch inner leaf

1 inch polystyrene

bitumen felt

3 inch outer concrete leaf or 4 ½ brick


Somewhat surprisingly the Scottish MBA certificate (quoted by Hotchkiss andEdwards) claims a U value of 0.17 W/m2K for these walls. The calculationdone for this thesis looks rather different:

Table 4: Bison Wall thermal characteristics results

Bison Wall frame Conductivity

W/(mK)

Thickness

mm

Inner surface 0.13 n/a

Gypsum plaster 0.51 10

High density reinforced concrete inner leaf 2.3 150

Expanded polystyrene 0.04 25

bitumen felt 0.23 5

High density reinforced concrete outer leaf or 4 ½ brick 2.3 (0.8) 75 (114)

Outside wall surface 0.06

Total Thickness 265 (292)

U Value 1 with concrete outer leaf 1.08 Wm2K

U Value with brick outer leaf 0.93 Wm2K1 Conductivity from Cibse and ‘Build Desk’. U values calculated using Build Desk 3.2 1

The Department of the Environment (DOE) Good Practise Case Study 121records 4 variations for this type of block with different insulation thickness:(DOE 1996)

Table 5 : Recorded Insulation thickness for LPS type blocks

Block Type Insulation Thickness

Northwood Tower Waltham Forest(1971)

Type not specified(21 storey)

25mm polystyrene

Rosemount street Glasgow (early

1970’s)

Reema Type

(12 storey)

40mm polystyrene

Rosset House Hull Yorkshire developmentGroup type (6 storey)

20mm polystyrene

Chertsey Crescent (1966) Wates type Block

(11 storey)

25mm polystyrene

The calculation in Table 4 includes an insulation thickness of 25mm.Increasing the level of insulation to 40mm in this type of sandwich wallconstruction improves the U value to 0.8 Wm2K

Note:It is not the purpose of this thesis to look at condensation risk in any detail, but, it isinteresting to note that the risk of interstitial condensation in this type of sandwichconstruction is considered high by the Build Desk programme used to calculate the UValues. It is surprising that the bitumen felt layer in this construction is outside the insulationlayer. It is there presumably to prevent the ingress of moisture from the air. There is no useof a vapour barrier on the inside of the insulation layer. It may be that the concrete issufficiently dense to act as one.


Cavity Walls: (Box frame and Column and beam systems)

Table 6 below illustrates the ‘Build Desk’ calculations for the U values typicalcavity wall constructions found in high rise blocks.

Table 6: Cavity Wall Thermal Characteristics

Cavity walls Conductivity

W/(mK)

Thickness

mm



Sand and Cement Render 1 12

Aerated Block 0.227 100

Cavity with 50mm mineral wool insulation ( or none ) 0.05 50

4 ½ brick external skin 0.8 114

Outside wall surface 0.06 n/a

U Value with insulation 0.51 Wm2K

U Value without insulation 1.06 Wm2K

Concrete Walls:

Table 7 below illustrates the Build Desk’ calculations for the U values typicalno fines concrete constructions found in high rise blocks.

Table 7: ‘No fines’ Concrete Thermal Characteristics

No fines concrete Conductivity

W/(mK)

Thickness

mm



Plasterboard 1 12

50mm mineral wool insulation ( or 25mm cork) 0.05 50

No fines concrete 1.13 300

Outside wall surface 0.06 n/a

U Value with mineral wool insulation 0.57 Wm2K

U Value with cork insulation 0.91 Wm2K

Thermal Bridging

It is important not to overlook the effects of thermal bridging on the overallthermal efficiency of high rise walls.

Table 8 : Typical thermal bridging components

Construction type Thermal Bridging elements

Typical Column and Beam Floors , columns, beams and window reveals

Typical Box frame Floors, window reveals

Typical LPS Floors window reveals

Typical Wimpey no fines Columns , floors , window reveals


As an example of this, the U value for a concrete column (300mm square) willbe 3.5 Wm2K. Typically, this would be adjacent to the cavity wall or thesandwich type LPS system wall with U values of 0.51 Wm2K and 0.93 Wm2Krespectively. Thermal bridging therefore brings down the overall U value of thewall considerably and is likely to induce condensation.

Windows : Types and U values

Original installed widows were, almost without exception, single glazed metalor wood framed as was the case for most housing types at this time.

The U values for a 2m2 wooden framed window with 4mm single glazing is4.86 Wm2K.

This compares with the target elemental U Value for windows under 2006Building Regulations standards of 2 Wm2K.

Infiltration

It is evidenced, particularly in the reports and investigations that followed theRonan point tragedy in 1968, that panel bedding and joint sealing especially inthe large panel systems was not done to a very a high standard . This resultsin high air infiltration rates and effectively high thermal bridging at these joints.

Other Construction Details

Form:

Simplicity of form is significant in this discussion, both for thermal bridging andfor ease of treatment.

Modernism generally spurned decoration, so these high rise blocks aregenerally flat and uncomplicated, and services are were usually internalised.

However, they are not simply flat. Balconies and walkways, for example arecommon features.

Common areas – buffer zones:

Lifts, staircases and landings, although unheated, provide thermal ‘bufferzones’ on two sides of most high rise flats.

Shading:

Overheating is not a problem that is generally associated with these high risedwellings, and despite the likelihood of the design creating intolerably warmconditions at times, there is no empirical evidence to suggest it is a seriousproblem at the moment.


This is probably because air infiltration is high and occupants are longsuffering.

In contemplating a refurbishment, and with the likelihood of a warmer climate,window shading may be needed. This is considered briefly in later chapters.

Heating

Heating of high rise blocks varies considerably, but two main factors seem tohave influenced the choices at the time of construction and whenrefurbishment options are considered

District heating was often installed. This provides efficiencies in terms of plant,installation, running and maintenance costs.

Gas was often overlooked because of the perceived danger of explosion,particularly after Ronan Point. The predominant form of heating in high risewas therefore under floor or warm air electric heating, both of which arerelatively inefficient and carbon heavy compared to other heating fuels.

Conclusions

There are four main types of high rise residential construction.Within the broad definitions of these types, there are manyoverlaps and variations.

Because of the way that these high rise blocks werecommissioned, thermal standards were not set, workmanship wasnot always good and exact records of construction details werenot often recorded.

U values of walls vary, but there is enough evidence todemonstrate that insulation was given some consideration indesign and construction.

However, although insulation standards are relatively goodcompared with many other contemporary construction types, theydo vary considerably, and thermal bridging through structuralelements appears to have been largely ignored.

District heating was seen to have advantages, but was installedinfrequently compared to less efficient electric flat based centralheating system.

The single glazing is typical of the times.


3.3. Understanding HighRise Buildings -Condition

This section looks briefly at the structural condition of high riseresidential blocks. It does this to try to establish whether theseblocks are in a good enough condition to merit large-scaleinvestment in modernisation and energy improvement measures.

It looks at structural condition because information is available tomake broad but pertinent generalisations about it, and becausethe structural condition is basic to a building’s longevity.

It does not look at the cosmetic, nor the environment, as these aretoo variable and are independent of the construction type. It doeshowever include a table from the English House Condition Survey,which estimates the financial costs of improvements of differenthouse types for Decent Homes purposes. This is includedbecause, although Decent Homes is in large part about kitchenand bathroom improvements, it does also include assessments ofcosts of basic repairs and some thermal improvements.1

Figure 9: The Collapse of Ronan Point ( Photograph BBC)

1 See glossary for Decent Homes definitions


Structural instability

Ronan Point opened the debate about workmanship, and structural conditionso it is here that the appraisal will start.

There is a lot of analysis of the incident. Rouse and Delatte (2003) is theprimary resource drawn on here.

When Ivy Hodge lit the match that caused the explosion in her 18th storey flat,the corner walls were knocked outwards by the force of the blast.

These walls were the only bearing for the walls above. As a result of theircollapse, the floors above gave way, loading floor eighteen, which then set offa chain reaction loading on all the floors below which collapsed like a set ofdominoes down to ground floor level.

In later analysis, three key problems were identified. Firstly, there was the factthat the Larsen-Neilson design had been intended for blocks of a maximum ofsix storeys. Ronan Point was 21 storeys high.Secondly, there had been no redundancy built into the design. In other words,if a failure occurred in any key component, there were no alternative loadpaths to support the structure above.Thirdly, and this was not fully revealed until some 16 years later when RonanPoint was systematically demolished by the architect Sam Webb, was theissue of bad workmanship. Sam Webb:

“I knew we were going to find bad workmanship – what surprised me was thesheer scale of it. Not a single joint was correct. Fixing straps wereunattached: levelling nuts were not wound down, causing a significant loadingto be transmitted via the bolts: panels were placed on bolts instead of mortar.But the biggest shock of all was the crucial H-2 load-bearing joints betweenfloor and wall panels. Some of the joints had less than fifty percent of themortar specified.” (Wearne, 2000).

Ronan Point itself was repaired and eventually with its eight ‘ sister ‘ blocksdemolished sixteen years later. In the immediate aftermath of the incidentreinforcement work was done to these blocks and to blocks of similar designacross the world.

Much criticism was rightly levelled at what had preceded, and this led towidespread changes in Building Standards Regulations.

Although Ronan Point blighted the reputation of high rise dwellings, it remainsthe only example of structural failure of a high rise residential building, and intheir conclusions to their investigation into the incident the BRE concluded thatthere has been ... :

“... no major failure of an LPS building in the United Kingdom since theappraisal and strengthening of LPS buildings was carried out following thecollapse at Ronan Point in 1968.” (BRE 1985)


Concrete Defects

Carbonation

Carbonation is a chemical process that takes place in the concrete, resultingfrom atmospheric Carbon Dioxide (CO2) getting into it, causing a reduction inthe alkalinity of the concrete and corrosion in the reinforcing bars (rebars) andultimately, spalling of the concrete. Problems are exacerbated if concretecover levels over the rebars are inadequate.(Davis Langdon and Everest 2002; Ciria1992)

Chlorides

Chlorides from salt and from chemicals added to speed the curing of concretein cold weather can result in corrosion damage to rebars and spalling ofconcrete.

Cover

Inadequate cover on rebars exacerbates the above problems and can lead tospalling due to water penetration alone.

Concrete delamination

Delamination of concrete sandwich panels occasionally happens, as does theseparation of cavity walls where wall tie failure occurs.

Joint failure

Cracking of joints in cast in-situ concrete sometimes occurs where theconcrete has not been given enough time to cure.

Extent of Concrete Problems

Comprehensive studies of structural defects in high rise blocks wereundertaken by the Building Research Establishment in 1987 and 1996.Further information comes from CIRIA.(1992)

Concrete spalling is a common and widespread problem, and although theBRE report that........

“Some cast-in-situ high-rise concrete buildings examined by BRE were inexcellent condition, demonstrating that it is possible to achieve good durabilitywith low maintenance costs by means of adequate quality control of materialsand construction and the application of protective coatings in service.” (Glickand Reeves 1996)

they also state that......

“Corrosion related defects were present in both the cast-in-situ elements andthe pre-cast components in the majority of buildings examined and in somecases had required extensive concrete repairs.”


It is apparent that concrete condition varies a lot between sites, but there areno recorded cases yet of the concrete being in any sense ‘beyond repair’:

“Some buildings were found to be virtually defect free and to have sufferedonly minimal deterioration whilst others of similar age and design were in needof extensive repair. In the majority of buildings inspected there were at leastone or two places where concrete cracking or spalling had occurred.

The standard and consistency of workmanship was found to differconsiderably between buildings of the same form of construction, both on thesame site and on different sites. However the standard of workmanship andconstruction practice was found to be reasonably consistent throughoutindividual buildings.

The quality of the pre-cast components was in line with observations of otherpre-cast work. In general, serious deterioration had not arisen so far. (Glick andReeves 1996)

In 1987, although they recommended the introduction of log books and annualinspection regimes, the BRE had no serious concerns about the structuralintegrity of high rise residential buildings:

“The BRE has found no LPS building showing structural distress sufficient togive concern for the safety of people, not has it received any reports of anyLPS building failing to sustain the loads experienced in service – including fireloads” (Currie et al 1987)

Nevertheless, concrete repairs will be in needed on all high rise blocks built inthe sixties and earlier, and complex access equipment is needed to carry outthe work.

It is this requirement that demands questions about whether the repairs areworth doing, and if the answer is yes, then what else should be done whilst theaccess equipment is in place.

Weather tightness

Vertical joints between panels seem to be the main point of weakness forweather tightness. These were generally neoprene, and not of the standardthat would be used today. With high levels of exposure, demands on materialsare great and many of these neoprene strips are now brittle and haveseparated from the structure, allowing the ingress of wind driven rain.

Horizontal joints were usually of ‘dri-pack’ cement and have generallyperformed better - where they were properly installed.

RepairsPatch repairs, involving cutting out and replacement of affected concrete usingproprietary mortars, are the solution to spalling caused by lack of cover,chlorides, and carbonation.


In addition, preventative measures such as the use of anti carbonation paintsand desalination techniques for chloride problems should be applied.

In cases of delamination, wall ties and resin grouts can be used to stabilisepanels.

For weather tightness, neoprene strips can be replaced with modernalternatives.

Over cladding adds further protection.

Cladding

Where insulation and aesthetics are also invested in, over cladding is theobvious solution.

Over cladding may be made from:

• Render

• Pressed metal , aluminium , steel , galvanised, plastic coated or stainless,often in ‘sandwich’ form with insulation

• Glass

• Glass reinforced plastic.

Cost

Secondary data on costs for this type of work is hard to obtain, and does notbear easy comparison. However the following table is indicative of theamounts involved:

Table 9 Indicative estimates for external repair costs to high rise blocks

Source Work as described Cost pro rata Cost for typical 16

storey block c

Render application

including insulation

£90.00 / sm £294,000

Rain screen claddingincluding insulation

£210.00 /sm £685,000

Concrete repairs and

prevention

£24 /sm £52,240

Access : item £70,000 £70,000

Davis Langdon and

Everest a

(2000)

Total external works £1,031,240

Sustaining Towers b ‘Permarock’ (GRC insulated

cladding) d£100/ sm £326,500

Aluminium insulatedcladding d Ave £220/ sm £718,000

a: Social Housing Dec 2002b: Sustaining Towers Websitec: Figure calculated using dimensions of Normandie Tower, Norwich : 3265m

2

d: It is not clear whether this includes access equipment


The case studies in chapter six include some actual project costs.

Repair Costs - Comparative

The following table from the English House Condition Survey2 is includedbecause it is the only source of comparative repair costs by house type that isavailable.

It would be wrong to make too much of this information, because it is a ananalysis for Decent Homes purposes. The criteria for Decent Homes are a bitobscure (see glossary) and the quality of the data questionable. Nevertheless,this is the official position, so it is interesting to note that according to this, highrise flats of this type have the third lowest average repair costs.

Table 10:Estimated

Costs for

DecentHomes

Improvements % in

this groupthat are:

nondecent

homes

failthermal

comfortonly

thosefailing

fitness,repair

ormoderni

sation

averagefloor

area(m2)

averageSAP

rating

average(mean)

repaircosts

(£/m2)

averageproperty

value

000s

alldwelling

sin the

group('000s)

dwellingtype

smallterraced

house

33.7 18.4 15.3 58 54 52 £115 2,629

medium/large

terracedhouse

29.8 15.1 14.7 92 53 46 £158 3,494

semi-detached

house

27.1 15.4 11.7 87 50 47 £161 6,127

detachedhouse

18.2 11.7 6.5 136 50 25 £298 3,631

bungalow 18.4 11.7 6.6 72 47 48 £163 2,072

converted

flat

44.8 17.3 27.5 60 43 71 £158 654

purpose

built flat,low rise

45.7 33.0 12.7 56 62 30 £120 2,677

purposebuilt flat,

high rise

51.5 31.7 19.8 63 52 39 £164 328


Conclusions

There are strong suggestions that the explosion at Ronan Point,the anti modernist sentiments of the late 1960’s and themismanagement of high rise estates, have contributed to arepresentation of the structural condition of high rise blocks aspoor.

The BRE generally found however that:

“Examples of cast-in-situ high-rise concrete housing builtfor local authorities between the early 1950's and early1970's examined by BRE, and reported on by localauthorities or their consultants, were found to bestructurally sound. No cases of structural inadequacy ofconcrete frames or cross walls were found during thesurvey.”

Concrete repairs, if not already done, are overdue on high riseblocks of this era.

It is the access equipment that is the really expensive part of theserepairs, and it is therefore at this time, that the opportunity shouldbe taken to invest in other improvements to the blocks.

According to the available data repair costs of high rise flats are infact lower than for most other types.


4. Environmental, Socialand Legislative Issues

This section looks at the issues which frame this thesis. It looks atwhy priorities in decision making about housing, need to shifttowards those that serve the environmental agenda.

It does this to examine whether debates about demolition, newbuild and refurbishment numbers should proceed with greaterurgency.

Climate Change

There is no need to add to words of the IPCC draft fourth assessment report of17th November 2007:

“Warming of the climate system is unequivocal, as is now evident fromobservations of increases in global average air and ocean temperatures,widespread melting of snow and ice, and rising global average sea level”

“Observational evidence from all continents and most oceans shows that manynatural systems are being affected by regional climate changes, particularlytemperature increases.”

“Most of the observed increase in globally-averaged temperatures since themid-20th century is very likely due to the observed increase in anthropogenicGHG concentrations” (IPCC 2007)

Policy implications for climate change are likely to be carbon pricing andrationing, resulting in effect, in a rationing of the right to burn fossil fuels.

Demand and Supply for fossil fuels

Demand

Demand for fossil fuels continues to increase as developing nations world gothrough their own industrial revolutions, and as the western world demandsgreater comfort levels.


Peak Oil

This term is used here in its most generic sense to mean the reduction in theworld’s ability to produce fossil fuels. The ‘peak’ date for different fuels andfrom different thinkers varies, but there is more or less universal agreementthat fossil fuels will become progressively harder to extract and thatconsequently, prices will increase.

Existing targets and legislative framework

The Climate Change Bill of 2003 put targets firmly on the UK agenda.

“Our ambition is for the world’s developed economies to cut emissions ofgreenhouse gases by 60% by around 2050. We therefore accept the RoyalCommission on Environmental Pollution’s (RCEP’s) recommendation that theUK should put itself on a path towards a reduction in carbon dioxide emissionsof some 60% from current levels by about 2050.”( DTI 2003)

This target is now widely seen as not sufficiently ambitious.

The Energy Performance of Buildings Directive drives the legislativeframework for energy reduction in buildings in Europe. This is primarilydirected at new build and is interpreted in the UK by the Building Regulations,the Code for Sustainable Homes, and energy labelling.

Current Policy towards existing buildings

Existing buildings are still much neglected in the drive towards energyefficiency.

A brief description of the policy measures below helps to demonstrate thepaucity of support (and consequent motivation of building owners) in this area.

• Funding for research on strategy and method, is directed towards anumber of organisations including the Building Research Establishment, TheEnvironmental Change Institute, The Energy Savings Trust, Tarbase, TheEnergy Efficiency Partnership for Homes, and further academic institutionsand commercial organisations.

• Energy labelling for housing is being introduced on the back of the HomeInformation Pack.

• The Energy Efficiency Commitment (EEC) requires energy suppliers tomeet energy efficiency targets. They do this by a contributing to a combinationof measures, including low energy lighting schemes, insulation, efficientappliance schemes, and heating schemes.It is ironic that at the same time they are driven by responsibility to theirshareholder to increase the sale of electricity. The EEC is changing to a


Carbon Emissions Reduction Target (CERT) in 2008 to include support formicro generation. Both the EEC and CERT are aimed primarily at low incomehouseholds.

The Decent Homes Programme and Warm Front incentivise improvements inenergy efficiency in the rented sector. Warm Front has been effective insubsidising cavity wall and roof insulation but Decent Homes, which is theprimary driver behind refurbishment of social housing stock, sets thermalcomfort standards too low, and is insufficiently funded to allow muchdiscretionary spending on insulation measures.

The Home Energy Conservation Act (HECA) 1995 gave responsibilities toLocal Authorities to report on energy efficiency measures taken for housing intheir areas, and consequently to devise targets for improvement. It is hard totell exactly how successful this has been as the reporting measures areinconsistent.

Support is largely directed towards building owners, and whilst tenants are theones who benefit there is little incentive for landlords to invest in fuel efficiencyimprovements.

In the later section on ‘Hard to Treat Homes’ it is shown that governmentstrategy in this area has traditionally been driven by fuel poverty issues andnot by the need to cut fuel use and carbon dioxide emissions.

Fuel poverty continues to be an issue and with the cost of fuel increasing it willbecome worse. Fuel poverty is, in part, alleviated by EEC initiatives, butprobably more so by direct subsidy to the fuel poor, such as pensioners winterfuel payments

Future Energy Strategy for Existing Buildings

“The domestic sector is a critical area to focus on. It consumes 28% of allenergy generated and is responsible for 27% of UK CO2 emissions.” (ECI2003)

Within the Buildings Sector space heating accounts for the largest proportionof total use.

Table 11: Total UK domestic energy consumption by end use (DCLG 2007)

2002(TWH) 2002 (%)

Space heating 337 61

Hot water 130 23

Lights & Appliances 72.5 13

Cooking 15.1 3

Total 554 100


There is a significant growth in consumption in domestic energy use in allsectors despite improvements in efficiency and Building regulations:

Table 12: Growth in Total UK domestic energy consumption by end use (DTI,2005)

(PJ) 1990 2002 Growth Growth %

Space heating 990 1213 223 12.3

Hot water 422 467 45 11.1

Lights & Appliances 228 261 33 11.4

Cooking 63.3 54.4 -8.9 -8.59

Total 1703 1995 292 17.1

The implications for housing of the 60% reduction target in the ClimateChange Bill of 2003 has been interpreted best for buildings by the ‘40%House’ research carried out by the Environmental Change Institute. (ECI 2003)

In aspiring to a ‘zero carbon’ UK, Zero Carbon Britain includes a morechallenging figure of 57% reduction in domestic demand for heat by 2027.(Helweg-Larsen et al 2007)

Both the ECI and ZCB identify the need for a dramatic increase in bothrefurbishment, and in demolition and new build.

At present, just 20,000 dwellings per year are being demolished and replaced(0.08%of the stock) and only 180,000 more are being built. (Helweg-Larsen et al2007), this despite the ambitions of the government’s own advice to build morethan 200,000 per year just to meet the needs of the market. (Barker 2004)

Both the 40% house and ZCB models require a large increase in investmentin energy efficient refurbishment. The 40% house proposes cuts in averagespace heating demand for existing homes from 14,600 kWh p.a. now to 9,000kWh p.a. in 2050 and ZCB aspires to cuts in space heating in refurbishedhomes down to 6000 kWh p.a.

Demolish or Refurbish?

Confronting the issue of energy efficiency in buildings means addressing keydecisions about which properties to demolish and rebuild, and which torefurbish.

Historically, demolition has been fairly widely spread across building types, butlargely determined by social and economic issues rather than technical andenvironmental ones.

It is the contention of many that energy efficiency should replace social issuesas the main criteria in deciding where to demolish, and that demolition andreplacement should be targeted along these lines.


In publication it has become an emotive issue, because the demolition ofhomes is seen as wasteful and even as an attack on architectural and socialheritage. Environmentalists are challenged by the idea that demolition andnew build may be more energy efficient and, in fact less wasteful, thanretention of existing stock.

It is true that refurbishment is cheaper in energy terms than demolition andnew build. According to ‘Constructing Excellence’ refurbishing to highresource efficiency standards has around one tenth of the carbon impact ofnew build. (Stock Take 2006)

It has been demonstrated however, that in many cases the energy payback ofthe embodied energy lost to demolition is in fact, quite short when replaced byhighly efficient new buildings.

“ Construction and demolition processes all use energy, but the amount isrelatively small compared to the energy consumption in the use of buildings.When an old, inefficient building is replaced by a new, efficient one, theembodied energy in the construction process will offset in a few years by themore efficient building in occupation: thereafter the more efficient building willrepresent savings throughout its lifetime “ (Boardman et al 2005 p43)

Case:A study by XCO2 (2002 p40,41) estimates efficiency savings after only 5 years with newbuild based on the following figures :New build designed to run at 1.5 MWh p.a.Refurbishment to run on 14 MWh pa.Embodied energy in new build 80MWhEmbodied energy in refurbishment 12MWh.

A study by ECI (ECI 2007App E p 5 ) frames a scenario in which the energy payback isabout 25 years for high efficiency refurbishment (9.5MWhpa) compared with new build(2MWHpa)

It is important to recognise that these outcomes depend on the new build andrefurbishment energy standards achieved, but even if the running costs were to be 5MWhand 10 MWh respectively (and even this is ambitious for new build) at the present time,the payback would only be 10 years.

If this is true, more detailed analysis is needed and building types should beassessed against the ease of their refurbishment in this way.

There is analysis of a tower block in these terms later in the thesis in chapternine.


Conclusions

Fuel and the right to emit carbon dioxide is likely to be rationed.

Space heating in housing is one of the most significant sources ofcarbon dioxide emissions.

Although little attention is currently paid to the existing housingstock, increasingly ambitious targets will be set for energyefficiency in buildings.

Demolition rates must increase to keep up with the demand forhousing.

The energy payback times for demolition and rebuild aresurprisingly short compared to refurbishment, but this doesdepend wholly on the standards to which the work is done.

The emphasis in the selection of which buildings to demolish andreplace will have to shift towards the most energy inefficient.


5. Classification andComparison

This chapter looks at the concept of ‘Hard to Treat Homes‘ (HTTH)and the way in which flats in high rise blocks have been includedin this classification. It looks at whether this definition is nowuseful and appropriate, or if with our growing appreciation of theurgency of climate change and energy issues, it is limiting ourunderstanding of the energy efficiency of buildings.

It then looks at the available national stock data in an effort to seehow high rise dwellings fits into it, in terms of thermalcharacteristics and repair costs, and finally to ascertain whetherthe label ‘Hard to Treat’ is an appropriate one to apply to high riseblocks.

Hard To Treat Homes (HTTH)

‘HTTH’ is an expression widely used by government, and affiliated pressuregroups, both in the understanding of housing energy issues and of fuelpoverty. It is in the latter area that the term has most widely adopted andarguably, most misunderstood.

The expression ‘Hard to Treat Homes’ (HTTH) is defined by the EnergySavings Trust as:

‘.... those that cannot accommodate standard energy efficiency measures.They may be built with solid walls or have no loft space; alternatively they maynot be connected to the gas network. Non-traditional building types forexample, high-rise blocks are also defined as hard to treat.’ (Energy SavingsTrust 2007)

It is quite easy to understand how solid walled houses and those with no loftcan be broadly classified as hard to treat, but to include ‘non traditional’ housetypes and high rise blocks, may be a generalisation too far.


The expression is now limiting because:

• It was defined at a time when ambitions for energy efficiency were lowerthan they are today. Hard to treat homes therefore usually include homeswith solid walls and no loft space.

• It was only really applied in terms of the potential for fuel poverty and thuslimited to the construction types and locations in which those likely tosuffer from this lived. The definition therefore often includes homes whichcannot accommodate energy efficiency schemes such as ‘Warm Front’ 1

where there is ‘no connection to low cost fuel such as oil or gas’. (EnergySavings Trust 2007)

• The knowledge we have of our housing stock is still insufficient to provideadequate analysis of types, numbers and energy efficiency.

It is important therefore to consider whether the use of this definition distortsour perception of different dwelling types

The Centre for Sustainable Energy have done the most comprehensivestudies of ‘Hard to Treat Homes’ (HTTH) in their two reports to the Hard toTreat Homes sub group of the Energy Efficiency Partnership for Homes (EEPH2006; CSE 2005). They are both based on interpretations of data from theEnglish House Condition Survey.

They researched access to gas and the prevalence of solid wall housing.Access to gas is not pursued here as it is common to all construction typesand, although impacting directly on carbon emissions, it relates more toaffordability of fuel than to energy use per se.

Solid walled housing is of interest here as this is a feature of some high riseconstruction types – notably Wimpey no fines.

The CSE acknowledge that the availability of adequate data limits theirapproach :

“It is also important to appreciate that the indicator is only intended as apredictor of‘ hard to treat’ housing. There are, of course, a range of otherfactors that can also contribute to ‘hard to treat’ but for which there is littlesmall area data. These may have particular significance at a small area level,e.g. use of non-traditional construction types”. (CSE p6)

In their ‘Fuel Poverty’ report the CSE conclude that:

“In general, low-rise non-traditional housing is more energy efficient thantraditional masonry dwellings with solid walls, but less so than traditional cavitywall housing. Of the main types of construction, non-traditional, medium andhigh-rise flats have the highest average SAP ratings. The very lowest SAPratings are to be found in both low and high rise non-traditional housing as

1 For Warm Front – See glossary


well as in traditional dwellings with solid walls. Some individual proprietarysystems provide mean SAP ratings that are significantly lower than theaverage for traditional solid walled housing.” (CSE p6)

The CSE do therefore recognise for the first time here, that high rise flatsshould not generally be considered as energy inefficient, and that they do notgenerally even fit the definition of being ‘solid walled’ and ‘off gas’.

Classification:

It continues to be surprising that we know so little about the construction typesand consequential energy performance of the housing stock in this country.Various initiatives and research projects seek to address this and part of therole of the recently introduced Energy Performance Certificates is to fill thisknowledge gap.

The classification of construction types and their energy efficiency, has for awide variety of purposes, been largely based on research gathered for theEnglish House Condition Surveys (EHCS) commissioned by the Governmentand updated annually. The Energy Savings Trust have also published figuresfor energy use by dwelling type based on Bredem methodology.

English House Condition Survey

There are about 21 million homes in the England. The EHCS results are basedon a sample of about 25 thousand – or just over one per cent - of those.

The reported results tend to be driven by policy areas and lately, DecentHomes is at the heart of the most recent report. Although The Decent Homestargets have a thermal comfort (energy) criterion to them, it is neither thefocus of Decent Homes – nor is it a high threshold that has to be passed tosatisfy it.1

It is the Stock Profile and the Condition of Homes sections of the EHCS thatare useful to this work, and these are included as Table 13 : Stock Profile(EHCS 2005) and Table 14: Condition of Homes (EHCS 2005)below.

1 The Thermal Comfort criterion of the Decent Homes Standard

Requirement Description

Efficient Heating Heating should be programmable

Effective insulation – gas /oil C/H systems )

Cavity wall insulation ( if appropriate ) or 50mm loft insulation(if there is a loft)

Effective insulation (Electricheating systems )

Cavity wall insulation ( if appropriate ) and 200mm loftinsulation (if there is a loft)


Table 13 : Stock Profile (EHCS 2005)

owneroccupied

privaterented

localauthority

RSL total

numbers of dwellings ('000s

dwelling age

pre 1919 3398 1,042 106 186 4,731

1919 to 1944 2,931 364 362 151 3,808

1945 to 1964 2,780 268 811 421 4,279

1965 to 1980 3,350 363 738 477 4,928

post 1980 2,873 430 149 582 4,035

dwelling type

small terraced house 1,704 445 270 246 2,665

medium/large terraced house 2,629 365 325 315 3,634

semi-detached house 4,728 447 419 302 5,897

detached house 3,512 220 9 11 3,753

bungalow 1,535 113 209 172 2,028

converted flat 288 309 42 78 716

purpose built flat, low rise 868 515 747 654 2,783

purpose built flat, highrise

67 54 145 40 305

dwelling size

under 50m2 1,068 573 602 593 2,837

50- up to 70m2 3,470 821 842 623 5,756

70- up to 90m2 4,749 596 596 473 6,414

90- up to 110m2 2,598 220 103 89 3,009

over 110m2 3,446 257 23 39 3,765

Neighbourhood RenewalFunded (NRF) districts

NRF districts 5,335 1,035 1,332 838 8,540

other districts 9,996 1,432 834 979 13,241

market conditions

Market Renewal Pathfinder

areas

411 115 202 114 842

other areas 4,920 2,352 1,964 1,703 20,939

broad regional areas

south east regions 4,492 944 667 563 6,666

northern regions 4,411 615 710 601 6,337

rest of England 6,428 908 789 653 8,778

nature of area

city or other urban centre 2,782 946 711 563 5,002

suburban 9,104 1,031 1,260 1,024 12,418

rural 3,445 490 195 230 4,361

occupancy

vacant 363 253 128 80 824

occupied 14,968 2,214 2,038 1,737 20,957

All dwellings 15,331 2,467 2,166 1,817 21,781


Table 14: Condition of Homes (EHCS 2005)

% in this group that:

... arenondecenthomes

...failthermalcomfortonly

..failfitness,repair ormodernisations

averagefloorarea(m2)

averageSAPrating

average(mean)repaircosts(£/m2)

averagepropertyvalue

alldwellingsin thegroup(‘000s)

tenure

owneroccupied

24.9 15.2 9.7 94 46 43 £204,971 15,331

private rented 40.6 19.4 21.2 72 46 70 £173,119 2,467

all privatesector

27.1 15.8 11.3 91 46 46 £200,556 17,798

local authority 33.7 19.1 14.6 63 55 50 £114,058 2,166

RSL 23.8 16.5 7.4 62 59 32 £120,665 1,817

all socialsector

29.2 17.9 11.3 62 57 42 £117,072 3,983

dwelling age

pre 1919 40.8 25.4 15.4 96 39 71 £213,480 4,731

1919 - 1944 30.0 15.6 14.4 88 43 65 £199,292 3,808

1945 - 1964 25.8 8.2 17.6 81 48 44 £160,943 4,279

1965 - 1980 28.0 5.6 22.3 80 51 34 £164,597 4,928

post 1980 10.8 1.1 9.6 83 61 12 £190,113 4,035

dwelling type

small terracedhouse

32.3 16.4 15.9 58 51 56 £127,656 2,665

medium/largeterraced house

29.0 14.6 14.4 92 48 49 £172,289 3,634

semi-detachedhouse

23.8 13.8 10.0 86 45 50 £173,138 5,897

detachedhouse

16.7 10.5 6.2 135 44 30 £311,681 3,753

bungalow 16.7 11.0 5.6 71 44 48 £170,394 2,028

converted flat 44.3 18.8 25.4 61 43 76 £162,483 716

purpose builtflat, low rise

44.3 32.2 12.1 55 61 33 £130,456 2,783

purposebuilt flat,high rise

50.3 29.5 20.8 61 60 45 £169,988

305

NRF districts

NRF districts 30.4 16.4 14.0 78 50 52 £155,156 8,540

other districts 25.6 16.0 9.6 90 47 41 £204,724 13,241

marketconditions

MarketRenewalPathfinderareas

36.5 15.0 21.4 72 49 68 £73,210 842

other areas 27.1 16.2 10.9 86 48 45 £173,398 20,939

broad regionalareas

south eastregions

29.3 17.1 12.1 85 50 46 £249,277 6,666

northernregions

27.3 15.9 11.3 83 48 49 £133,446 6,337

rest ofEngland

26.3 15.6 10.7 87 46 43 £174,125 8,778

nature of area

city or otherurban centre

36.5 18.3 18.2 75 50 58 £174,630 5,002

suburban 24.2 15.2 9.0 83 50 41 £172,493 12,418

rural 26.4 16.3 10.2 105 42 45 £233,956 4,361

occupancy

vacant 51.0 20.1 30.9 76 47 95 £164,256 824

occupied 26.6 16.0 10.6 86 48 44 £186,117 20,957

all dwellings 27.5 16.2 11.3 85 48 46 £185,290 21,781


Table 15 below draws out the facts most relevant to this work.

Table 15: Condition of Homes Extracts from ECHS (EHCS 2005)

High riseFlats

Highest Lowest Mean High Rise- Rank (out of 8)

% age in this groupthat are :

50.3 16non decent homes 50.3

High Rise Det. house/ bungalow

32 8th -

Highest

32.2 10.5fail thermal comfort only29.5 Low rise Det. house

18 7th --

2nd highest

25.4 5.6those failing fitness,repair or modernisations

20.8

Convertedflat

Bungalow

14 7th -

2nd highest

135 55Average floor area (m2) 61

DetachedHouse

Low riseflat

77 1st -

Smallest

61 43Average SAP rating 60

Low riseflat

Convertedflat

50 2nd best

76 30Average (mean) repaircosts (£/m2

45

convertedflat

detachedhouse

48 6th most

expensive

£311,681 £127,656Average property value £169,988

Detachedhouse

Smallterraced

£177261

5th most

expensive

5,897 305All dwellings in thegroup (‘000s

305

Detachedhouse

High Riseflat

2723 lastSmallest

What can be learned from this

High rise flats have the highest proportion of ‘non decency’. This may bebecause most high rise flats are owned by Local Authorities (LAs) andRegistered Social Landlords (RSLs), and are let as social housing. Socialhousing has suffered from a lack of investment over the last 30 years.

Similarly, high rise flats have almost the highest level of failure on thermalcomfort standards. This may be for the same reasons. However it is difficult toreconcile this with the figures for SAP1, and with the fact that most high riseconstructions had basic levels of insulation installed during construction.

High rise flats are the smallest of the house types classified.

1 SAP : See glossary


High Rise flats have the second best SAP rating. This seems surprising in thelight of the fact that they are the least ‘decent’ and are included in the categoryof ‘hard to treat homes’.

High rise flats have the 6th highest per metre repair costs. There is a simplerelationship between size and cost that is reflected here.

Energy Savings Trust

Figures from the Energy Savings Trust , which are again drawn from theEnglish House Condition Survey in Table 16 tell us that the flat is the mostenergy efficient of the 2 bedroom dwelling types surveyed.(EST 2006)

Table 16: heating costs and carbon dioxide emissions by dwelling type

Gas Heating Electric HeatingProperty Type Bedrooms kWh/yr kgCO2/

yrkWh/yr kgCO2/yr

Flat 2 11,423 2,170 8,626 3,709Mid Terraced House 2 11,693 2,222 9,057 3,895End Terraced House 2 15,138 2,876 12,222 5,255Semi-Detached House 2 18,373 3,491 14,886 6,401Detached House 2 24,412 4,638 20,092 8,639

Conclusions

“The hard to treat stock is generally properties that have any ofthe following features: solid walls, off the mains gas network, noloft space, high-rise blocks, or for other technical reasons cannotbe fitted with standard efficiency measures” (DCLG 2006 p12 )

The classification of Hard to treat Homes in the above way isoutdated and needs reviewing in the light of current environmentalpressures.

The available knowledge of the housing stock in the UK is poor,relying as it does to such an extent on the English HouseCondition Surveys and their subsequent analysis for differentpurposes.

Such data as there is, tends to support the view that high risedwellings are in fact some of the more energy efficient dwellings inthe English housing stock and that their inclusion in the


classification HTTH is, at the very least subject tomisinterpretation.

The next Chapter looks in more detail at the costs and practicaldifficulties of improving the thermal characteristics of high riseblocks.


6. Case Studies

This chapter looks at some recent and ongoing examples of highrise refurbishment contracts.

It does this to assess to what extent energy efficiency is aconsideration in key decision making about the maintenance andimprovement of high rise blocks, and to assess the drivers behindthese decisions.

It does this also to look at published and reported figures forenergy savings and consumption so that comparisons can bemade between these and the analyses later in the thesis.

It is a collection of information that informs the work, rather thananalysis, as the quality of the information falls short of the detailrequired for this.

Finally there is a paragraph about demolitions

Introduction

The examples are drawn from two sources.

The public domain

There are a few examples of high rise refurbishments, redevelopments, andinitiatives that are written about in sufficient useful detail on the ‘world wideweb’ for inclusion here.

There are no selection criteria for their inclusion here except that they areavailable.

These are:Glastonbury House. PimlicoFlats in Makartstrasse Linz GermanyOzolciema iela 46/3 Riga Zemgale. Latvia

Also included are descriptions of work from published BRE Good PractiseGuides research documents. The information is relevant to the work, but it isover 20 years old


Primary Research

First hand research of particular case studies was done in London andNorwich.

These were selected on the basis that either they were local and records ofwork were made available, or because large scale refurbishment projects wereongoing at the time of the research, and the participants were receptive torequests for information and assistance.

These are:

Little Venice Towers, Westminster

Kestrel House, Islington

Six Towers, Norwich


Glastonbury House

Table 17: Glastonbury House basic information

Location Pimlico, London

Owner Westminster City Homes

Height (storeys) 22

Flats 131

Construction type Post and beam

Principal Construction

Architects , Consultants

Integer , Enabling Concepts , Westminster Homes

Principal Contractors Wates Construction

Glastonbury House, is the most often cited example of a ‘sustainable’ high riserefurbishment.

It was heralded on its completion by John Prescott as:

“the UK's first intelligent and green residential tower, clearly a truer, betterbuilding.” (Enabling Concepts 2002)

The key features announced at planning stage were these:‘Intelligent Home Control’; ‘Integrated Reception System’; networked cablinginfrastructure for DTV and broadband to every flat; potential 'free' telephonesystem throughout the block for calls between flats; resident involvementthroughout the development process; new neighbourhood centre and on-sitemanagement office to provide care and support for residents; wastesegregation; target 50% reduction in energy consumption and carbonemissions; more efficient heating and lighting; photovoltaics; wind turbinetarget 40% water savings; rainwater harvesting; dual-flush toilets; roof topresidents' 'Sky Lounge'. (Wates Construction Ltd.)

Table 18: Glastonbury House. Key (predicted) performance data1

Space heating energy consumption:

Before refurbishment: 9830 kWh/flat per year

After refurbishment: 7000 kWh/ flat per year

Saving of around 29%

CO2 saved due to renewable energy

integration:

2,365 kg/a

Refurbishment cost: €14.48 million (£9.5million)

1 The predicted performance data was supplied to ‘Euroace’

1 by Enabling Concepts who

worked on the project for Integer:


NoteIt is interesting to compare these figures with those supplied by Norwich City Council forWinchester Tower, and those estimated by the IES simulation, both in Chapter 7.

In the Winchester tower example, the average heating load per flat is 9,700Kwh (a 78%proportion of the total boiler load derived from fuel supplies), which is similar to thosequoted for Glastonbury house.

The IES simulation of Normandie Tower(the sister block to Winchester Tower) calculatedpotential improvements to the heating load per flat of up to 86% with the addition of100mm external insulation and 2006 standard double glazing. This compares with atarget of 29% (50%) for the Glastonbury House project.

Figure 10 : Glastonbury House proposal (Image : Cole Thompson Anders Architects. )

Commentary

Glastonbury House was not externally insulated. The walls remained as brickcavity walls with probably no more that 50mm insulation in the cavities. Theenergy savings therefore were principally from heating system improvements(connecting to the Pimlico District Heating Scheme), and double glazing andbalcony enclosure.

This project seems to have been principally aimed not at cutting energy use,but more at a sustainability agenda that was more about social and housingsustainability.


Unfortunately (and typically of the industry) there is a lot of information aboutthe project at planning stage and very little information about it afterwards.It has been impossible to establish exactly what was installed and what it’sperformance is.

It is interesting to note however, that the principal consultants on the projecthowever predicted an energy saving of about 29% and not 50% which was theforecast in the contractor’s publicity, and that the wind turbine was definitelynot installed.


Makartstrasse Flats

Table 19: Makartstrasse Flats : basic information

Location Linz Germany

Owner Not known

Height (storeys) Not known

Flats 50

Date of construction 1958

Construction type Not known . Photograph suggests cast in situ cross

wall concrete

Principal Construction Architects ,Consultants

Bmst. Ing. Alfred WillensdorferGIWOG Gemeinnützige Industrie-Wohnungs-AG

Principal Contractors Not known

This is an exemplar project in terms of energy saving. It originally aspired toPassivHaus1 standards, but fell short of this.

The improvements depended largely on the development and application of anew prefabricated facade, with built in windows and high levels of insulation.This new facade with negligible air infiltration is the key to the overallimprovements in energy performance on the project.

As part of the facade, the balconies were enlarged and enclosed to includeinsulated parapet walls and side frames, effectively increasing the living areaof the flats.

Services improvements included connection to a new district heatingcombined heat and power plant (CHP), and heat recovery ventilation.

Unlike most British examples, some post occupancy energy monitoring figuresare available:

Table 20: Makartstrasse Flats. Post Occupancy Costs, Energy and Carbonperformance.

Space heating energyconsumption:

Before refurbishment: 179kWh/ma

After refurbishment: to 13,3 kWh/ma

Saving of around 446.800 kWh/a

CO2 saved 147 kg/a (per flat)


integration:

None

Refurbishment cost: Not known

Additional costs to achieve passive

house standard

27%

1 For PassivHaus – see Glossary


Note

This equates to space heating saving of 93%. This is equivalent to the saving achievedfor the mid floor flat at Normandie Tower analysed in Chapter 7 with a total annualheating load of 630 watt hours (down from 9000 KWh).

Figure 11 :

Makartstrasse Flats before

the refurbishment

programme

(Photograph: gap-solar.)

Figure 12:

Makartstrasse Flats afterthe refurbishment

programme

(Photograph: gap-solar)

Commentary

This project was an experimental and demonstration one in which the aimswere specifically to try to reproduce ‘PassivHaus’ principles in an urbanrefurbishment project. Although falling some way short of PassivHausstandards, it appears to have been successful.


Ozolciema iela 46/3

Information on this project came from Euroace.

Table 21 : Ozolciema iela 46/3, basic information

Location Riga Latvia

Owner Not known

Height (storeys) 9 Storeys

Flats Not known

Date of construction Not known

Construction type LPS - Lightweight single layer prefabricatedconcrete panels

Principal Construction Architects ,

Consultants

Not known

Principal Contractors Not known

The improvements on this project were primarily aimed at insulation of thefabric including external insulation to the walls, double glazing, and re roofing.The district heating system was also overhauled.

The walls were externally insulated using 80mm slabs (probably rockwool)which was screened and rendered.

Table 22: Ozolciema iela 46/3. Cost, Energy and Carbon Performance


Before refurbishment: 155 kWh/m2a

After refurbishment: 73 kWh/m2a

Saving of around 53% or 82 kWh/m2a

CO2 saved 1,395 kg/a or 57%

CO2 saved due to renewable energyintegration:

Not known


There is not a lot of available information on this project, but it tells us energycosts were more than halved through apparently simple measures of insulationand heating improvements

Figure 13: Ozolciema iela 46/3 (Photograph Euroace)


Examples from the Building Research Establishment

The BRE have recorded a number of improvements to high rise blocks whichare published under their own banner and that of the Department ofEnvironment (DOE).

They are of limited value to this work because they are all over fifteen years.However, in the interests of seeing how understanding and priorities havechanged in this relatively short time, it is still interesting to note some generaldetails from some of these reports.

The DOE Good Practice Case Study 121 for instance, records ‘ energyefficient’ improvements to six LPS blocks – all carried out in the late 1980’s.

‘Improvements’ include:

• Over cladding with rendered 50mm polystyrene or 80mm mineral woolslabs

• Electric storage heating.

• Draft stripping to windows

• Off peak immersion heater control

• Prepayment meters.

Measurements of energy saved are made in terms, but in terms of the costs ofheating per flat not as is generally done now, in terms of U Values, SAP, orkWh. This makes comparison with contemporary projects difficult.

Commentary

Whilst the improvements are valuable, they are of a relatively modest standardand this perhaps reflects the priorities of the time.

The use of energy costs per flat as a measure of savings tells us that fuelpoverty was of greater interest than energy use, and reflects on the fact thatstandard measures are not yet settled even now in a business that is stillevolving fast

Further research into these case studies can be done following the sourcesrecorded in the Bibliography.


Little Venice Towers , Westminster

Information about the project was made available from site visits, the maincontractors and the architects, in interview and by e Mail.

This project comprises the internal and external refurbishment of 6 high riseblocks in Little Venice London in 2007/2008. These are Polesworth House,Oversley House, Wilmcote House, Princethorpe House, Gayden House,Brindley House.

Table 23: Little Venice Towers - basic information

Location London Borough of Westminster

Owner Westminster Homes

Height (storeys) 20

Flats / maisonettes 99

Date of construction

Construction type Wates LPS system

Principal Construction Architects ,Consultants

Kemp, Muir Wealleans

Principal Contractors Wates Construction Limited

Table 24: Little Venice Towers . Cost Energy and Carbon Performance


Before refurbishment: Figures not available

After refurbishment: Figures not available

Saving of around Figures not available

CO2 saved Figures not available

CO2 saved due to renewableenergy integration:

Figures not available

Refurbishment cost: Approximate break down of cost (millions)

External Works

Render 1.2

Concrete repairs 5.5

Cladding 5.5.

Windows 4

Access equipment 2

roofing 0.5

Sub total – external works 18.7

Internal Works

Kitchen and Bathroom 4.5

Lifts 2.5

Heating 11.8

Refuse chutes 0.75

Other 1.75

Sub total – internal works 21.3

Total 40


The principal energy improvement measure was to upgrade the thermalperformance of the external walls by insulating them. This was done in themain with 100mm of Rockwool. This was applied to the walls behind analuminium frame. Under the windows an insulated render system wasemployed, as these were lightweight panels that could not support the load ofthe aluminium panels.

Although designed by architects, Kemp Muir Wealleans, the contract was a‘partnership’ with a large design and build element to it.

According to Martyn Kemp of the architects

“No we did not work out the heat loss improvement on any scientific basis. Ourclient had to meet ‘Decent Homes Standards’ which just requires a reasonableimprovement. As we did not have to meet any specific standard we includedenough insulation to meet the current building control standards but were notrequired to procure any specialist calculations to prove the improvement. I amafraid this is not the scientific answer you wanted but the standards are notspecific on this point.” ( E mail 02.01.2008)

New heating was installed. There was no mains gas in the blocks, so thearchitects specified electric storage heating and water heating by Elson as themost cost effective to install.

According to the contractors, demolition was never considered as an option asthis would have been “too expensive”.

No consideration was given to renewables.

Commentary

Although a lot of money and attention was given to insulating these blocks,there is nothing to suggest that this was done with much detailedpremeditation. There does not seem to have been any particular brief orunderstanding relating to the thermal performance of these blocks, theinsulation merely coming as part of the cladding package. In further support ofthis suggestion is the use of electric water heaters, the absence of anyconsideration given to renewables and the lack of any energy performancecalculations.

I am very grateful to Anthony Dickins and Prija of Wates Construction Ltd, andMartyn Kemp and Ken Lee of Kemp Muir Weallams architects for theirassistance and time to discuss and show me around this project.


Before refurbishment the Little Venice Tower blocks were unsightly LPSsystem built dwellings :

Figure 14: Polesworth House before refurbishment

as the scaffolding is being erected

(Photograph: Author)

Figure 15: Wilmcote House after refurbishment withthe scaffold being dismantled.


Figure 16: Over cladding and insulation detail on

Little Venice project.



Kestrel and Peregrine Houses

This project comprised the major refurbishment in 2007/2008, driven largely bythe need for concrete repairs and by the imperatives of the Decent Homesprogramme.

Information about the project was made available from site visits, the maincontractors and the architects, in interview and by E Mail.

Table 25: Kestrel and Peregrine Houses – basics

Location London Borough of Islington

Owner Homes For Islington

Floors and Flats Kestrel House 17 floors 101 flats

Floors and Flats Peregrine House 26 floors 155 flats

Date of construction 1963 –1967

Construction type LPS with brick in fill panels under windows


Consultants

Homes For Islington

Principal Contractors Apollo Construction , DNS concrete repairs

The LPS wall panels are 300mm thick comprising (from outside to in) 250mmdense reinforced concrete, 35 mm cork and render and plaster finish.

The design work was done by ‘Homes for Islington’. The Islington EnergyOffice was not included in the design proposals and there is nothing to suggestthat thermal efficiency was an integral consideration in the design. Whenasked, the design team said that it was “not practical to do wall insulation.”

Table 26: Kestrel and Peregrine Houses. Cost, Energy and Carbon performance


Before refurbishment: Not known

After refurbishment: Not known

Saving of around Not known

CO2 saved Not known


integration:

Not known


Islington Energy Office became involved in the project when they saw anopportunity to use a high rise block to fulfil a commitment they had to installfour wind turbines in the borough.

Kestrel House and Peregrine House were assessed for this installation.Peregrine House was excluded because of the amount of telecommunicationsequipment already on the roof.

A feasibility study was carried out for the installation on Kestrel House:


Table 27: Wind turbine feasibility figures

Kestrel House Wind turbine project

Size 6kw

Anticipated annual output 13,000 to 18000 kWh

Average annual demand of common areas 102,000 kWh

Estimated cost of electricity for common areas £714

Estimated cost £35,000

Estimated saving (15.5 kWh @7p per unit) £1085

Estimated Revenue (@£40.00 per MWh per ROC) £620

Total revenue £1705

Simple Payback calculation1 21 years

Figure 17: Kestrel House, Islington , soon to be

home to a wind turbine


Commentary

The driver for the external parts of project was the concrete repairs.

Replacement windows were being fitted because the old ones were no longerserviceable – and because they are a popular improvement for occupants.

Some of the original concrete detailing made over cladding more challengingthan in other blocks that have been looked at (see photograph chapter eight),and this may be one reason why improving the thermal performance of thewalls was not done. It is surprising though, that this never seems even to havebeen part of the proposals, despite having full scaffold in place.

Calculations on ‘Builddesk’ give a U Value of 0.89 W/m2k for these walls,which is only slightly better than an uninsulated cavity wall. (See table in chapter3.2).

1 No allowance is made for maintenance in this calculation.


Energy efficiency was not a design consideration, and the wind turbine wasonly proposed as highly visible part of a political drive to be at the cutting edgeof the ‘green’ agenda in London.

It is interesting to compare the payback times for the wind turbine withpayback times for external insulation seen later in the work.

I am very grateful to Graeme Lowe and Steven Henn of Islington EnergyOffice, Rob Forest of Homes For Islington and Apollo Construction for theirtime in interviews and for showing me around the site, whilst underrefurbishment.


Six Towers, Norwich.

This project comprised concrete repairs and external refurbishment to Aylmer,Seaman, Markham, Compass, Burleigh and Ashbourne Towers, completed in2005. Information was from interviews and a printed archive provided byNorwich City Council.

Table 28: Six Towers Norwich – basics

Location Norwich

Owner Norwich City Council

Floors and Flats 11 storeys and 44 flats in each block

Date of construction 1965 -1968

Construction type Post and Beam with Brick in fill panels


Consultants

Norwich City Council

Principal Contractors CityCare , Gunnite

The towers are of reinforced cast in situ concrete post and beam constructionwith brick in fill panels of cavity brickwork with approximately 50mm cavityinsulation installed at the time of construction.

The towers were suffering from spalling concrete, which by 2000, had becomeso bad that consideration had to be given to fencing off areas outside thetowers to protect the public from falling debris. Tests indicated that theproblems were being caused by a combination of poor ‘rebar’ cover andcarbonation.

Other problems in the blocks related to cold common areas, and condensationfrom ‘cold bridging’ problems.

Table 29: Six Towers Norwich. Cost, Energy and Carbon performance


Before refurbishment: Not known

After refurbishment: Not known

Saving of around Not known

CO2 saved Not known

CO2 saved due to renewable energyintegration:

Not known

Costs

Concrete and miscellaneous repairs £650,000

Access equipment £550,000

Total £1,200,000


District heating from CHP had been installed in the three tower blocks in theMile Cross area of Norwich and PVCu double glazing had been installed in allblocks in about 1985.


Commentary

The district heating installation had addressed any fuel poverty issues thatthere may have been here, so insulation was not thought to be a priority whenthe concrete repairs were done.

Nevertheless, this is another example of access equipment being raised forconcrete repairs and no additional work being done whilst it was in place. Inthis case the reasons given for this were largely funding related. Norwich CityCouncil owns these blocks. Had they been part of a stock transfer to aRegistered Social Landlord, it may be that additional funds could have beenfound to replace the windows, enclose the balconies and externally insulate.


Demolitions

It has not been possible to establish how many residential tower blocks havebeen demolished, or exactly why decisions were taken to demolish them.The website UK Housing Wiki which is a collaborative site (and thereforelargely unsubstantiated) records 187 cases of demolitions to date in thirteencities in the UK. There are obvious omissions from the list and there is everyreason to think that the total might be twice as many as this.

Reasons given for demolitions are more often than not given by localpoliticians, and tend to include emotive descriptions of urban blight, damp,flooding and structural problems. More often than not in fact, demolition takesplace as part of regeneration of an area and is seen as a kick-start to theprocess, enabling funding for new housing for new communities.

An air of celebration almost always accompanies explosive demolition.


Commentary and Conclusions

These case studies will be drawn on to illustrate points made later in the work,but there are some interesting points that merit raising now.

Energy savings do not appear to be at the heart of refurbishment programmeson domestic high rise.

Where energy saving measures have been included they seem to be ancillaryto the concrete repairs and aesthetic improvements. Even in the case of theLittle Venice project there is a surprising absence of standards and scientificprinciples , preferring instead a ‘hit and hope’ approach.

In the Islington case, a high rise block has been used as a green flagship tofurther the environmental cause and the credentials of the borough.

There is no substitute for basic insulation improvements if the object is toreduce energy consumption however.

The European examples, particularly the German one appear to take theenergy issues further. This would tie in with Germany’s other achievements inthis area.

The agenda for energy savings has changed a lot in the last twenty years, andis still evolving.

Figures for energy use and energy saved are still published in different waysso do not bear comparison in every case.

It is unusual to find any reliable ‘post occupancy evaluation’ to assess theactual achievement of projects such as these.


7. Analysis of HeatLoads in High RiseResidential Buildings

This chapter reports on the analysis of the heat loads of high risedwellings.

The analysis is based on:

• Observation

• The IES VE thermal simulation tool

• Reported actual energy use.

None of these methods provides the absolute answer. Eachcontributes to our understanding of the situation and illustratesmethods that can be used by building owners to assess the actualand potential energy performance of their buildings.

The analysis is done to try and estimate the effects of differentimprovement measures on the thermal performance and fuel useof a high rise block.

Observation

It is important to observe and understand before analysing, both to illuminatethe analysis and to try to understand what to expect from it - and why.

What is it about high rise dwellings therefore that might give reason think thatthey are heat efficient or heat inefficient, and what special characteristics is itimportant to be aware of?

On the side of efficiency are:

• The ‘’buffer” effect of adjacent dwellings.Each flat only has two outside walls. The others benefit from the adjacencyto other flats or to the common areas.Similarly, with the exception of the ground and top floors, the floor andceilings benefit both from being protected and heated by the otherdwellings above and below.

• Simplicity of form is very helpful in external insulation, there being fewservices to move or obstacles to build round. Most high rise buildings forinstance have internal rainwater down pipes.

• The potential for district heating


• The fact that high-rise blocks are rarely considered beautiful – and oftenugly - means that over cladding may be welcomed rather than feared.

On the side of inefficiency are:

• The height of the blocks mean that over cladding and window replacementare much harder than they would be for low rise dwellings. This is reflectedin the cost of the work.

• The height also gives greater exposure to wind and sun, makingconsideration of build quality, orientation, ventilation, and shading moreimportant. (With this however comes the potential to take advantage of thisexposure through harnessing wind the wind and the sun for energy.)

Conclusion

Critical observation and understanding therefore suggests that improving thethermal performance of high rise dwellings should achieve good results butperhaps at a high cost.

The IES analysis :

Why thermal modelling for this project?

Thermal modelling has been used to aid our understanding of this issuebecause:

• Improvements to the thermal performance can easily be assessed andcompared.

• Computer analysis is quick, and changes to models can be made easily.Once the model is set up, what would have taken days in the past can bedone in minutes now.

• It enables the thermal performance of the high rise block to be analysedwithout the vagaries of occupant behaviour.

Limitations of computer thermal modelling

It is important to recognise the limitations of thermal modelling as well as thestrengths, so as to properly understand the conclusions that can be drawnfrom it.

There are imperfections in all modelling programmes:

• In building the model, input and process errors can easily be made.

• Whilst construction elements can mostly be accurately assessed andmeasured, some factors can’t be. Ventilation rates, for example, areestimated. In reality, these vary a lot between dwellings and these


variations depend on small things, such as distorted or ‘painted up’windows

• Occupant behaviour has as big an impact on thermal performance as doesthe construction. Occupants may choose to ‘live cold’ or insist for exampleon open windows when they sleep.

These factors mean that the greatest strengths of computer simulation are notin predicting actual energy use, but in demonstrating relative performance ofdifferent construction make ups.

Checks

Checks were made against results by:Revisiting the data, checking the input values against Cibse values, applicationof common sense, and calculating the U Values of the walls separately usingthe Build Desk programme, referenced in chapter two.

IES Thermal Simulation Methodology

Accurate dimensions and assessment of construction details are necessary todo this modelling.

Accurate plans are hard to come by for high rise blocks because details wereeither lost by building owners or transferred to microfiche. Some buildingowners have transferred these to computer readable files, but the detail isoften poor and the drawings are no longer not to scale.

Information

Normandie Tower , Rouen Rd, Norwich was chosen because access wasmade available by Norwich City Council. Within the block, one flat had beencompletely gutted after a fire, so the construction details were exposed.Measurements were taken on site to establish exact construction details forinput to the model.

Plans supplied by Norwich City Council, and the relevant specification ofconstruction details are included as Appendices.

The actual figures for energy consumption were only obtained after the IESanalysis was completed. They apply to Winchester Tower, the sister towerblock to Normandie Tower, constructed at the same time and to the samespecification.

Conductivity figures to calculate U values were sourced from CIBSE Guide A


Other variables for the modelling were sourced form IES itself – or fromexperience. All relevant variables are included in the Appendices.

Figure 18: Normandie Tower IES Model

Figure 19: Normandie Tower

Photograph

(Photograph: Author )


Analysis

The Models Explained

The analysis looks at two simple options for the preservation of heat, externalinsulation with cover cladding, and replacement glazing. It compares the heatrequired in five models with different configurations of insulation and doubleglazing.

This approach has been taken because windows and walls constitute thewhole envelope of most high rise flats, and insulation of these elements is thekey to energy saving. These also represent the most accessible and readilyunderstandable options for building owners.

The Models analysed :

Model 1: As built . ‘No fines’ concrete walls and 4mm singles gazing

Model 2: As existing. ‘No fines’ concrete walls and 1985 double glazing.

Model 3: Walls insulated with 100mmm rockwool and cladding, and windowsas existing.

Model 4: ‘No fines’ concrete walls and 2006 Building Regulations standarddouble glazing.

Model 5: Walls insulated with 100mmm rockwool and cladding and 2006Building Regulations standard double glazing.

More details of the constructions and modelled variables can be seen in theAppendices.

The simulation results are broken down into heat demand for space heating,and boiler load for space heating and hot water. This project focuses on spaceheating, as hot water demand is similar in all dwelling types, and largelydependant on occupant rather than building characteristics. In this casehowever kerosene is the fuel used for both space and hot water heating, so itis necessary to include the analysis of both in order to compare it with the fueluse figures supplied.

Results

The Whole block

The results of the simulation in Table 30 illustrate a potential reduction overexisting performance of 86% in heat demand for the block, cutting it by 544MWh p.a. - from 634.5 MWh p.a. in the original construction to 90.31 MWhp.a. in Model 5.


Table 30: IES VE Analysis of Boiler loads for Normandie Tower –(Whole Block)

Heating

Load (MWh) p.a.

Boiler Load

(Heating and HW )(MWh) p.a.

% age savings

over existing p.a.

Block Averageper flat

Block AverageHtg

Htg andHW

As Built – ‘no fines’ walls and single glazingModel 1

933.34 9.82 1194.26 12.57 n/a n/a

Heating is 78% of total boiler load

As existing – ‘no fines ‘ walls and 1985 double glazingModel 2

634.5 6.68 901 9.48 n/a n/a

Insulated walls and 1985 double glazingModel 3

273.48 2.88 499.38 5.26 56.90% 44.57%

‘no fines‘ walls and 2006 double glazingModel 4

157.88 1.66 370.79 3.90 75.12% 56.84%

Insulated walls and 2006 double glazingModel 5

90.31 0.95 295.6 3.11 85.77% 67.19%

The most significant gain is from insulating the walls. This is the case becausethe walls constitute the largest external surface area (78%), and the U value ofthe walls is being cut by over half from 0.54 to 0.28 W/m2k.

Flat by flat results

Table 31 breaks down the results into across section of individual dwellings.This level of analysis gives us further insights into the thermal dynamics of theblock:

• Heat demand is much higher on the top and ground floor illustrating thelevel of heat loss through the flat roof and into the ground. The flat roofcould relatively easily be improved, but the replacing of the ground floorwould be much more disruptive. Both these could be easily modelled, butwould add little to the overall debate.

• Orientation makes a small but significant difference.

• Heat demand reduces and then increases going up the block.

This type of analysis would be very useful to building owners in engagingoccupants with the potential improvement process as they can easily assessthe level of savings they might make individually. This may also have a moredirect impact on the assessment of fuel poverty issues.


Table 31: Flat by flat results of IES.VE analysis

Model 1 – As built . ‘No fines‘ walls and single glazing

Flats : MWh GF 1st floor 8th floor 14th floor Top floor

Flat 1 2bed NW Facing N/A 12.46 11.85 12.38 13.79

Flat 2. 2 bed flat SW facing 17.06 10.51 9.99 10.92 12.02

Flat 3. 1 bed flat N facing 12.55 8.07 7.74 7.8 8.6

Flat 4. 1 bed flat S facing 11.6 7.03 6.69 7.5 8.43

Flat 5.2 bed flat SE facing 16.92 10.28 9.75 10.16 11.41

Flat 6. 2bed flat NE facing 18.56 11.74 11.19 11.99 13.27

Model 2 - Existing. ‘No fines‘ walls and 1985 double glazing








Model 3 – 100mm External insulation and 1985 double glazing








Model 4 - ‘No fines’ walls and 2006 double glazing




Flat 3. 1 bed flat N facing 5.28 1.19 0.93 1 1.62




Model 5 - 100mm external insulation and 2006 double glazing









Analysis : The benefits of sharing walls and heat

For this experiment Flat 2 was ‘ taken out’ of the block and analysed as if itwere a bungalow with a solid ground floor and flat roof of similar constructionto flats in Normandie Tower. The walls and glazing received the sametreatment as the flats in the blocks in the various models.

This represents what is probably a hypothetical scenario (although there weremany no fines concrete houses built in the 1960’s), but nevertheless helps toilluminate the heat sharing and insulating effects that flats have on each otherin a block.

The modelled ‘bungalow’ now has four outside walls and exposed flat roof andfloor.

Table 32: Comparison of heat loads for flat and same construction bungalow.

2 Bed flat converted to bungalow (Flat 2) – Compared to Results for 8th floor flat

Heating loads (MWh p.a.)

‘Bungalow’ 8th Floor flatModel 1 As Built – ‘no fines’ walls and single glazing

40.4 10.74

Model 2 As existing – ‘no fines ‘ walls and 1985 double glazing34.95 5.38

Model 3 Insulated walls and 1985 double glazing31.56 2.08

Model 4 ‘no fines‘ walls and 2006 double glazing30.7 1.02

Model 5 Insulated walls and 2006 double glazing27.38 0.44

Actual Figures

Norwich City Council supplied the figures for oil consumption at WinchesterTower, the sister block to Normandie Tower.1 These are produced in full in theAppendices, but summed up and compared with the IES analysis in Table 33below.

1 Winchester Tower was constructed at the same time and to the same specification asNormandie Tower. Winchester Tower has a slightly older average tenant than Normandie.


Table 33: Actual and IES simulation figures for whole block boiler loads

Heat and Hot water MWh Difference

Actual 2005/2006 ( Winchester Tower) 1184

IES VE modelled ( Normandie Tower ) 901 23%

There is a significant difference in the amount of oil actually used and thatcalculated in the simulation.

The difference could be accounted for by a number of factors including:

• Human behaviour,

• More air infiltration than allowed for in the model.

• Greater than estimated inefficiencies in the boiler and heating system.

• Greater hot water use.

• Conversion rates. NCC have applied a figure of 10.6 to convert the oil tokWh. This is a bit higher than the generally accepted figure of 10.3 used bythe Department of Trade and Industry (dti) among others and takes noaccount of distribution losses or boiler efficiencies.

• Other inaccuracies in the models

Correction

Having discovered this difference, it is important to assess how much it affectsconfidence in the results of the IES analysis.

Whilst it would have been good to achieve a result closer to actual, it would bea mistake to do it by trying to adjust the inputs to fit.

The introductory paragraph highlighted the importance of IES VE in analysingrelative improvements in thermal performance rather than absolute ones, andthe analysis is still perfectly valid for this.

In terms of absolute values for thermal performance, lengthy site evaluation toassess the actual performance of the flats and their occupants would bevaluable.

It is quite satisfactory to accept the analysis and work in the knowledge of thislimitation and to aspire to do longer term research into the actual performanceof buildings that have had this type of improvement work done.

Potential Savings

Projected financial, energy and carbon savings can now be calculated forthese models from the savings figures in Table 30 above.


Table 34 : Projected savings in cost of oil (per annum) from insulation measures

Oil used Cost

Existing – ‘no fines ‘ walls and 1985 double glazing

Actual 111754 ltrs £37,748

Model 3 Insulated walls and 1985 double glazing

Projected with 44.57% saving £20923

Model 4 ‘no fines‘ walls and 2006 double glazing


Model 5 Insulated walls and 2006 double glazing


The 67.19% saving on boiler load between the existing Model (Model 2) andModel 5 represents a potential saving of 53,000 litres of oil, equivalent to about£18,000 (at today’s rates) and 14,045 kilograms of carbon dioxide.1

With available estimates varying around an average of about £1 millionpounds2 to do this work, the ‘simple’ payback period looks unattractive at 55years. But although the payback period is important, it requires the use ofprojected fuel prices such as ‘Fuel Prophet’3 might give, and does not take intoaccount offset costs and other benefits to the occupants arising from the work.

Conclusions

Thermal performance analysis of Normandie Tower a ‘no fines’concrete construction high rise block was carried out usingobservation, IES VE analysis and actual fuel use data.

The analysis indicated that some dramatic potential energysavings are possible using external insulation and double-glazingalone.

The modelling results showed a potential reduction in averagespace heating demand in the flats, from 13MWh per flat as built, to1.25 MWh with these measures.

This compares well with available benchmarks. The currentaverage for UK housing stock is 14MWh, and the 40% House

1 Current price of oil taken as 35 p per litre. Conversion rate for Kerosene (10.3 KWh per litreof oil) from the dti. Conversion rate for oil ( 0.265 Kg Co2 per Kwh) from Energy SavingsTrust.2 Estimated using Sustaining Towers website figures and Little Venice figures (Chapter 6)

3 Fuel Prophet is a software tool that forecasts the effects of fuel price increases on paybacktimes for investments in energy efficiency.


scenario target average for 2050 is 6.8MWh (Boardman et al 2005 p40).

The figure also compares well with PassivHaus and AECBstandards.1

There did however, prove to be a significant difference betweenactual and predicted fuel use. Although this impacts on the valueof the analysis it does not significantly undermine it.

More detailed analysis based on observation and evaluation ofactual data would be useful.

Using the model to ‘take out’ the flat from its context usefullydemonstrated the buffer effects of its neighbours on fuelconsumption for space heating, and showed why the flat can haveso much more potential for low energy use, than a detachedhouse, for example.

Differences in construction type and complexity of form mean thatother high rise blocks will present greater challenges thanNormandie Tower, both to the modeller and to retrofittinginsulation.

1 See Chapter 9 for further details


8. Improvements toThermal Performance -Potentials andPracticalities

This chapter looks at the practicalities of improving the energyperformance of high rise buildings.

One of the key drivers behind this work is the conviction thatinsulation comes before renewables in the drive to save energy inhousing, and it is on this therefore, that this chapter concentrates.

This chapter also looks briefly at opportunities that are specific tohigh rise blocks for improvements in the efficiency of heatingsystems, and the installation of ‘renewables’.

Access

Access is the issue which, more than any other, influences the approach toimprovement and remedial works on high rise buildings.

In the case studies in chapter six, access costs in the Westminster andNorwich examples were about £300,000 per twenty one storey block and£90,000 per eleven storey block respectively.1 It is important therefore, that ifaccess equipment is going to be erected, maximum possible advantage ismade of it, and that workmanship is of the highest quality so that maintenanceis minimised.

1 See chapter six – case studies


External insulation and cladding

Choice of materials / systems1

Ventilated or unventilated systems are the two basic choices for externalinsulated cladding of high rise blocks,

Unventilated systems, where the protective cladding is hard up against theinsulation, are more commonly specified. Ventilated systems do have theadvantage that any interstitial condensation will be dissipated more easily butunventilated systems are easier to install and take less space.

The protective coating is usually finished with a polymer based render onmesh that can be presented as pebbledash, brick slips, or coloured at theclients discretion. The improvement in looks of a block is one of the greatadvantages of external cladding.

Figure 20: Aluminium over cladding at

Little Venice has dramatically improvedthe look of the blocks

(Photograph Author)

Problems associated with installation of over cladding include:Wind loadings, metal fatigue to fixings, over stressing foundations, weathertightness, fire spread, colour change, and pollution.(Brookes A 1998)

Form

It has been argued that the simple form of the high rise block makes themconducive to external cladding and insulation. This was so in the NormandieTower example used in chapter seven, but is by no means always the case.

1 Permarock, Sto , Weber and Alumasc systems are the market leaders. Their products werelooked at to inform this section, together with those sources listed in the bibliography


Many brick built houses with complex architectural features and surfacemounted building services present a much greater challenge to externalinsulation. Although form is not generally as complex on high rise as on these,high rise blocks are not just the flat boxes they are sometimes thought of.

Features include balconies and sculpted concrete, such as that at KestrelHouse as well as raised and indented panels, all of which require additionaldetailing if they are to be successfully clad.

Figure 21: The corrugated

concrete at Kestrel House has

been expertly repaired.

The complication of this profile and

other detailing makes over claddingmore complicated(Photograph Author)

The installation of external cladding requires cutting in around thesearchitectural details. Window sills need extending, and any externally mountedbuilding services (usually just lightning conductors in high rise buildings) needremoving and replacing. Adaptations to flues and extractor ducts and terminalsmay be necessary and movement joints in the substrate also need to beaccommodated in the insulation system.

The more complex the work, the more likely that the workmanship will be poor,air infiltration levels may not be cut as much as anticipated, and maintenanceproblems may arise.

Figure 22 : Detailing for cladding

installation

(Kemp Muir Wealleans)

Form also takes in aesthetics here. It is much more palatable to over clad anugly plain building than a complex and attractive one.


Weather

Extreme weather conditions can prevail high up. Suction loads from wind andrain loadings that are not met at ground level must be catered for.

Workmanship

It is imperative that workmanship is of the highest quality to avoid thermalbridging, infiltration and weathering problems.

Fire

Fire testing at the BRE (Colwell and Martin 2003) has concluded that spread of firethrough thermosetting insulation1 and expanded polystyrene is too great toallow their use on multi-storey buildings, unless a barrier of Rockwool isincorporated at each level. In practise this means that Rockwool is theinsulation of choice for most, if not all, proprietary insulation systems forexternal application to multi-storey blocks.

Condensation

The British Board of Agrement Certificates for external cladding (Swisslab 2003)state that high internal moisture content internally could result in interstitialcondensation but not in the insulation itself. This seems unlikely and in anyevent can be calculated prior to installation and prevented through theinstallation of efficient ventilation systems.

Internal Insulation

Internal insulation is an option that has been chosen by a number of landlords,but has normally been done on a ‘piecemeal’ basis in response to extremecondensation problems – caused by uninsulated walls and cold bridging, oftenexacerbated by lifestyle issues.

It is more straightforward than external insulation in the sense that it can bedone flat by flat and does not require access equipment to do the work.However, disruption to the occupants is extreme. There is a loss of floor spaceand, if workmanship is not of the highest quality, interstitial condensation islikely.

There is also a loss of thermal mass, but in the case of high rise blocks thereis enough concrete in the floors and internal walls for this to be insignificant.

There are enough good throught the enclosed balco reasons for insulatingexternally that it is the default choice, but internal insulation can be moreappropriate where the form of the building externally is so irregular thatexternal cladding is impractical, or where other external works are not takingplace requiring access equipment.The Blades Rise Estate in Sandwell is an example of large-scale internalinsulation. (Trim 1991)

1 See Glossary. Includes Polyisocanurates, phenolic foams and polyurethane.


Balcony enclosure

Glazed balcony enclosure is often a good choice if access equipment is inplace, particularly where the balcony is recessed on the face of the building,such as at Glastonbury House.

If used properly and oriented right, solar gain through the enclosed balconycan give considerable fuel and ‘feel good’ benefits to the occupants.

Balcony enclosures can also reduce wind noise and cut down on the problemswith pigeons that are commonly associated with high rise living.

Roof Insulation

Roof insulation benefits the top floor flats, and it almost goes without sayingthat when the roof surface needs recovering, the insulation should beupgraded to the highest standards. Although easier with external access, it canbe done independently of other external works. Some owners haveapproached this by ‘pitching ‘ the previously flat roof. This often provides anaesthetic improvement as well.

Most high rise roof spaces have been let to telecommunication companies,who may install bulky equipment, which can seriously obstruct improvementsto the roof surface.

Glazing

Windows generally have shorter life span than other elements of the externalenvelope. For this reason, a lot of high rise blocks seem to have had windowreplacement programmes in the early 1980’s, often before concrete repairswere really needed. Early forms of PVCu double glazed windows weregenerally the replacement of choice, and in a number of cases externalcladding was also done. PVCu profiles from this date have developedproblems with discoloration and have become brittle. In many cases they nowneed replacing again.

There is nothing complicated about window replacement in high rise buildingsexcept access and ensuring that the workmanship and materials are goodenough to last in the demanding conditions.

With access so difficult, windows of the highest available (proven) qualityshould be installed when access equipment is in place.

Although there are many sound environmental reasons not to use PVCu, thetechnology has improved, and there are compelling arguments for using it inwindows in situations where access for maintenance is difficult.


Heating Improvement OptionsIn 1991 the Building Research Establishment published figures for the installedprimary heating type in high rise residential blocks. (Trim .M. 1991). Electricity at56% was the most common form installed in high rise ahead of gas (32%)solid fuel (7%) and oil (2%).

Electricity was often installed because it was thought at the time, to be thecheapest, and the safest. This was generally in the form of under floor or warmair heating, both of which later came to be relatively expensive and subject tosystem failure.

Oil, some gas and solid fuel systems were generally district heating schemesrun from central boilers often serving more than one block.

The concentration of properties under one landlord and geographically closeaffords the opportunity for very efficient district heating and combined heat andpower installations

However, existing infrastructure often determines the possibilities for heatingreplacements. Where electric heating has been installed originally, it is oftenseen as the only practical option to replace this with new electric heating – asin the case of the Little Venice project written up in chapter six.

Gas is currently the most efficient and cheap readily available fuel, butlandlords are very reluctant to install gas mains in tower blocks where therewere none previously for reasons of cost and perceptions about safety.

Existing district heating schemes benefit from the greatest efficiencies asopportunities arise for their replacement with combined heat and power.(Norwich and Aberdeen (EST 2004)) or as in the case in the Sheffield Road flatsin Barnsley (Ashden Awards) the replacement of coal fired district heating boilerswith wood pellet systems.

Photovoltaics

The facades of high rise blocks could be suitable for the erection of photovoltaic (PV) panels. Research only revealed one example of this being done.This was on Bowater House in Sandwell, where a small 4KW array wasinstalled in 1999. (Save Energy)

High rise rooftops are generally too small and often too crowded, to make asignificant contribution to either electricity or hot water generation, but they dohave the advantage of not being liable to shading. There are PV panels on theroof of Glastonbury Tower in London, but there is no information available onthe size and generating capacity.


Solar Century have installed panels to the facade of the CIS Tower, an officebuilding in Manchester. Performance figures are not available for thisinstallation.

This could serve as a model for the potential for PV in domestic high risebuildings. However, office buildings, and this building in particular which has aflat glazed facade, are usually better suited in use and design to theapplication of PV facades.

The web site reports that the... “7,244 solar photo voltaic panels, designed to convert daylight into electricity,will create 180,000 units of renewable electricity each year” (Co op bank)

They state that the cladding project cost £5.5 million to do, but there is noestimate of what cost can be offset from that amount to get the true extra overcost of the solar panels. They do claim however that the

“PV panels are cheaper than most commonly used high quality claddingmaterials.”

There isn’t adequate information to make a proper assessment of this but, at£5.5 million, the pay back period at today’s rates for electricity and RenewableObligations Certificates1 (ROCs) is about 250 years, so it is unlikely thatlower profile housing projects are adopted as exemplars for this technologyuntil the costs come down a long way - or prices go up.

One of the factors contributing to this relatively poor performance is the angleof tilt and orientation of the panels. The following table illustrates the point.

Table 35: How Orientation and Tilt affect Photovoltaic Electricity Generation

Potential

‘ Retscreen’ 2 simulation for high rise in Manchester with no shadingAverage Energy Generation

Orientation Tilt Generation

kWh/m2/day

Difference from

Optimum

South 35 deg 3.00 Optimum

South Vertical 2.18 17%

South Horizontal 2.63 12%

East / West 35 deg 2.46 18%

East / West Vertical 1.63 47%

East / West Horizontal 2.63 12%

The table shows that that efficiency of the PV cells is compromised by 17%when placed vertically as a building facade, and that east or west facingfacades suffer a 50% loss in efficiency.

1 For ROCs see glossary.

2 For Retscreen see Bibliography


Solar thermal

Similar issues apply to solar thermal installation, although it might beadvantageous use it to preheat some domestic water with panels on the roof.

Installations on a flat by flat basis are probably impossible because there isusually no stored water in the flats themselves, either because they areconnected to district heating systems or because they use combination typeboilers.

Wind Power

The Islington case study case in Chapter 6 analyses the potential of windpower on Kestrel House concluding a simple payback of twenty one years.This seems reasonable, with turbines generally having a simple maintenanceschedule and a long life, but the figures have yet to be substantiated.

Energy for Sustainable Development carried out a feasibility study on windturbines for high rise dwelling blocks in Bradford (ESD 2003); They concludedthat the best potential payback period was 17 years even allowing for a 50%grant towards installation. This was for 6kW ‘Proven’ type turbine – the sametype being installed in Islington.

Putting economic feasibility side, it should be remembered that the visibility ofthis type of project acts as a great proclamation of commitment to renewablesources of energy, which arguably has great value in itself.

"It's not going to generate loads and loads of electricity but it is a symbol ofwhere we should be going with renewable energy."(Ian Simpson, Bradford Community Housing Trust Executive Director 2007)

Limitations of these projects include potential structural problems and thepossibility of vibration in the flats below. These issues have yet to be fullyexplored. It may be of interest that Energy for Sustainable Developmentdeclined to supply any contact details or post installation information on theBradford development.

Wind power on high rise buildings is therefore significant for its symbolic andpolitical value, if not for its economic benefits. There may of course still betechnologies to be developed that take particular advantage of the windconditions around high rise buildings. Generally though, wind turbines arelikely to be better suited to new build projects rather than retrofits.

Management and Tenure

This work has deliberately stayed away from discussion of management andownership issues, but in this chapter is important to note that occupiers canmake or break energy efficiency improvement programmes, and theirinvolvement ins crucial in the success and ambition of these projects.


Tenure can also make a significant difference. The installation of energyefficiency improvements can sometimes be held back by the changing tenureof blocks. Leaseholders for example, can be reluctant to invest inimprovement schemes.

In the case of the Little Venice project, the project manager from WatesConstruction Ltd reported that leaseholders supported the project because ofthe potential increase in property values arising from it, but there have beenreports of improvements being blocked by leaseholders where paybacksappear more marginal.

Conclusions

High rise blocks have particular challenges, but also offer particularopportunities for the installation of energy efficiency measures.

Each case needs individual assessment based on the criteria here.

A key conclusion however is that, if access equipment is erected for anyreason, then full advantage should be taken of it to carry out widespreadimprovement works and that this work must be done to the highest standard tominimise long term maintenance.

The retrofitting of renewable energy technologies on high rise blocks isimportant for its visibility, but the practicality and economics appear verychallenging for most landlords at present.


9. The EnvironmentalImpact of Demolition,Replacement andRefurbishment of HighRise Blocks

Chapter four looks at the demolition / refurbishment debate ingeneral terms and concludes that demolition and rebuild isgenerally more energy efficient over the lifetime of buildings thanrefurbishment

This chapter looks at this debate with specific reference to highrise residential blocks.

It uses Normandie Tower in Norwich as a case study for thisresearch.

It looks first at what the embodied energy of a tower block is.

It then looks at the embodied energy in the refurbishment of thetower block.

The running costs of the tower block and the running costs ofreplacement houses are then calculated. These are combined withthe figures for embodied energy, to compare the life time energycosts of the two types.

Finally, it also looks at the implications for land use if high riseblocks are replaced by low-rise housing.


What is in a tower block?

Table 36 shows the calculations done for this paper of the embodied energyand carbon dioxide in Normandie Tower.

It is limited to the fabric of the building and does not include services, fixtures,or fittings.

In the table the embodied energy source data comes from Bath University.(2007). The density figures for materials are sourced from IES VirtualEnvironment programme. The density figure for no fines concrete areincreased to allow for high density beams and columns. The figures for thewindows are based on 3980 mj per 1.2 x 1.2 window (Asif et al)

By Bath University’s own admission their figures are need further work. Forexample, these are ‘cradle to gate’ and in some cases ‘cradle to site’ so do notinclude integration into the building. This is probably a very small proportion ofthe costs, but a significant one nevertheless.

Construction processes and energy costs change. It is the replacement energyand carbon costs of the tower block that are being analysed, and not theoriginal cost of construction.

Nevertheless, it gives some indication of the investment in the structure, fromwhich we can summarise more accessibly as follows:

Normandie Tower contains 21000 tonnes of materials produced at acost of 7,100 megawatt hours (MWh) of energy and 3000 tonnes ofcarbon dioxide.Of this, 20,500 tonnes (or 98%) is concrete produced at a cost of 6000MWh and 2646 tonnes of carbon dioxide.

James Livingstone

89

Table 36: Calculation of Mass. Embodied Energy and Embodied Carbon in Normandie Tower

General description : 16 storeys. 95 flats. Central core with services , lift, stairs and access corridors to flats

Materials

External Walls

Thickness

Area m2

Volume

m3

Density

kg/m3

Total

Weight

Embodied

energy

Mj/Kg

Embodied

energy

Mj

Embodied

carbon Kg

Co2 /Kg

Embodied

carbon

Kg Co2

Pebble dash

10mm

3265

32.65

1800

58770

0.15

8815

0.08

4701

External render

25mm

3265

81.62

1300

105638

1.52

1,60569

0.228

24085

‘No fines’ Concrete

300mm

3265

979.5

1700

16655150

0.81

13,490,672

0.102

1,698825

Glass Fibre Quilt

50mm

3095

154.75

12

1857

28

51996

1.35

2506

Plasterboard

13mm

3095

40.23

950

3990

2.7

10773

0.24

957.6

Plaster

5mm

3095

15.5

1200

18600

1.8

33480

0.16

2976

Floors

Dense cast concrete

250mm

5760

1440

2000

2880000

2.36

6,796,800

0.265

763200

Flat Roof

3 layer bitumen felt

15mm

459

6.88

1700

11696

75

877200

3.8

44444

Ply

25mm

459

11.47

700

8029

15

120435

0.75

6021.75

fibreglass

100mm

459

45.9

12

550.8

28

15422

1.35

743.58

dense concrete slab

150mm

459

68.85

2000

137700

2.36

324972

0.265

36490

Plaster

13mm

459

5.97

1200

7164

1.8

12895

0.16

1146

Internal Walls (Dividing )

Plaster

13mm

2853

37.09

1200

44508

1.8

80114.4

0.16

7121.28

Cast Concrete

130mm

2853

370.9

1500

556358

2.36

1313005

0.265

147434

Plaster

13mm

2853

37.09

1200

44508

1.8

80114.4

0.16

7121

Windows

Materials

Area

Units

No

Embodied

energy

mj/unit

Total

embodied

energy

Embodied

carbon Kg

Co2 /unit

Embodied

carbon

Kg Co2

Double glazed PVCu

2 X 4mm

924

1.44m

2745

2980

2,220,100

372.5

277512

Totals

25597363

3025284


The Embodied Energy of the Replacement Dwellings

Figures for the embodied energy of new dwellings vary widely:

Table 37: Embodied Energy of new buildings (ECI 2007 p1)

Source EmbodiedMWh

Notes

Sustainable Homes– low estimate

22 Given as 250 kWh/m2. Assumed floor area= 88 m2 average

Sustainable Homes– high estimate

44 Given as 500 kWh/m2. Assumed floor area= 88 m2 average

Empty HomesAgency

90 Subject to error according to Killip et al (ECI2006)

Buchanan & Honey– low estimate

60 Based on New Zealand construction - nottypical of UK

Buchanan & Honey– mid estimate


Buchanan & Honey– high estimate


BRE – low estimate 28 Quoted in XCO2 2002

BRE – high estimate 70 Quoted in XCO2 2002

XCO2 80 Based on other studies

Table 37 above gives a wide range of figures for the embodied energy in newdwellings.

Normandie Tower

Normandie Tower comprises 95 dwellings.

To replace these 95 dwellings therefore would cost anywhere between 2,090MWh (Sustainable Homes Low Estimate) and 13,680 MWh (Buchanan andHoney high). The average figure is 7885 MWh.

It is not really possible to convert this figure to carbon dioxide without the sourcedata on production methods and fuels used.

Given the variation in the estimates, the figure of 7,100 MWh produced in theanalysis in Table 39 does not compare too badly, particularly when taking intoconsideration the apparent naivety of the science.


The Embodied Energy in Tower Block Refurbishment

Estimating the energy costs of the tower block refurbishment is far from straightforward.

The only available figure for the embodied energy in refurbishment at the timeof writing is that quoted by David Ireland of the Empty Property Agency (no date):

“The total embodied energy in building a house can be added up. For what it’sworth it’s normally about 90,000kWh for a new family house. Comparing thatwith refurbishing a house let’s take a typical £40,000 refurbishment of a derelictthree bedroom semi. A refurbishment of this kind would use about 15MWh ofembodied energy.”

It is possible to look at some of the materials. In this case, the primary materialsfor energy saving are the double glazing and the external insulation.

Permarock, the system recommended and used in the simulation models inchapter seven comprises 100mm rockwool with a protective coating of ‘a highpolymer content cementitious material and reinforcing mesh ’ and galvanisedsteel framework and fixings.

Permarock insulation board has embodied energy of approximately 91 megajoules per metre squared for 60mm thick insulation (Permarock Ltd Specification

2006).

The Normandie Tower example uses 100mm rockwool so 40mm needs addingas per table 38 below:1

Table 38: Calculating the embodied energy of insulated cladding

Thickmm

Aream2

volm3

densitykg/m3

weightkg

Emb.energy

Mj/xx

Emb.energy

Mj

Emb.energy

MWh

Permarock 60 3265 n/a n/a n/a 91/m2 297115 825

Rockwool 40 3265 131 12 1572 16.8 26409 7.3

Table 39: Calculating the embodied energy of new windows

No Embodied energymj/unit

Embodied energymj

Emb energyMWh

Windows2 745 2980 2,220,100 617

These two improvements represent an energy investment of 1449 MWh, whichequates to 15.2 MWh per flat. This is very close to the figure from the EmptyHomes Agency above, but bear in mind that the comparison between therefurbishment of a family house and the over cladding of a tower block is not agood one. In the case of Normandie Tower, there is no allowance for internal

1 Embodied Energy base figures from Bath University ICE as per table 39 above

2 3980 mj per 1.2 x 1.2 window ( Asif et al)


refurbishment and updating. It would not be unreasonable to add a third to thisfigure to account for this to say 20MWh.

Running costs

This section looks at the running costs in energy terms of the flats to see howthey compare with published benchmark figures.

In the Normandie Tower IES VE analysis in chapter seven, space heatingdemand was estimated to reduce overall to 90 MWh, or to an average of 1.25MWh per flat, or 25 kWh /m2 with the two improvements cited above.1

Table 40: Benchmark figures for energy use for space heating from hot water

Measurement Standard Energy use standard

UK Average1 140 KWm2/year

BedZED1 16.2 KWm2/year

AECB Silver2 40 KWm2/year

AECB Gold2 15 KWm2/year

Passivhaus2 15 KWm2/year1 BedZED Bioregional2 AECB

The Normandie Tower improvements therefore compare quite favourably withbenchmark standards, falling between the AECB Silver and Gold standards.

Total Energy Returns from Refurbishment and Rebuild

This section combines the energy in use with the energy used in new build orrefurbishment, to compare the total energy use over the lifetime of a flat in therefurbished Normandie Tower and a dwelling built to the PassivHaus standard.

The information is presented in the graph below.

The tower block energy line starts at 15.2 MWh (the amount of energy taken torefurbish the block) and climbs at 1.25 MWh per annum, (the average annualenergy consumption per flat). The PassivHaus line starts a 60 MWh ( theamount of energy required to build the PassivHaus and climbs at an annualrate of 0.8 MWh. The crossover occurs in about 2110, when the theoreticallifetime energy requirement for the PassivHaus is less than that for therefurbished tower block.

1 Error allowance of 25% made based on calculations in Chapter 7


Figure 23: PassivHaus and refurbished flat. Lifetime energy use compared

The graph shows us that, even with PassivHaus standards it takes over ahundred years to make the ‘in use’ energy savings necessary to outweigh thedifference in embodied energy investment between the refurbished high rise flatand the new build.

The impact on land use of the demolition andreplacement options

The last section in this chapter deals with demolition and land useusingNormandie Tower as the case study.

Normandie Tower contains 95 flats.

The flats have an average floor area of 50m2

The total footprint of the block is 460 m2.

It is unusual for a high rise block to sit in less than 8 times its own footprint, soan allowance of 3680m2 is made. This is equivalent to about 0.9 acre or 0.32hectares.

Normandie Tower then, can be said to have been built at a density of about 294dwellings per hectare.

Combined embodied and in use energy for space heating

0

20

40

60

80

100

120

140

160

2010

2018

2026

2034

2042

2050

2058

2066

2074

2082

2090

2098

2106

2114

Date

Energy in MWh

Energy used per flat (refurb) 1.25 pa

energy used per newpassivhaus 0.8 p.a


Development densities for new dwellings vary according to locationdwellingtype and local planning policy. Some examples of urban densities are givenbelow:

Table 41: Examples of development densities

Development density/hectare Source

New developments

Poundbury 30 1

Greenwich Millennium village 292 (134 according to Rogers) 2 (3)

Olympic village Barcelona 71 3

Average density of housing developments inLondon 1997 -20003

78 3

Existing Developments

Paris centre 300 4

Kowloon centre 1700 4

Guidelines

Planning Policy Statement 3 Planning

guidance

Minimum 30 5

1 Society Guardian 31.07.02 2CABE Building for life

3 Rogers.4. Society Guardian 25.06.035 PPS 3. P 17

Where tower blocks have been demolished it has been done largely for socialreasons, and they are not replaced by other tower blocks. This would be seento be repeating the same ‘mistakes‘.

It is likely therefore that the replacement dwellings will require as much as twicethe land as the demolished tower block occupies. Bear in mind also thatNormandie Tower stands at a relatively modest 15 storeys high. The impactdoubles for blocks of thirty storeys, of which there are many examples.

The point is well made by Rogers however that achievable density is as muchabout good and appropriate design as it is about numbers.

Richard Rogers in his ‘Housing for a Compact City ‘ report for the Mayor of Londonsuggests that terraced housing, medium rise and high rise (20 storeys) can be built in thesame plot, giving very different results in terms of privacy and amenity, but resulting in thesame density. His figure is 75 dwellings per hectare which seems to give a larger thannormal space around the tower block and no parking for the terraced housing development.(Rogers 2003 p 20)


Conclusions

This chapter concludes that the approximate energy costs ofdemolition and replacement of Normandie Tower or an equivalentTower Block is 7885 MWh (the energy required to build theequivalent number of replacement dwellings).

This does not take into account the hazards and cost associatedwith demolition.

It also concludes that refurbishment to the levels in chapter sevenis more cost effective than demolition and replacement, (in overallembodied and ‘energy in use’ terms) for at least 100 years.

With regard to land use, tower blocks are a high density form ofhousing and fill the a current need in terms of the size andaccommodation type. Demolition and replacement places demandson infrastructure and ‘greenfields’. A rational housing policymaximises high density housing because delivery of facilities canbe so much more efficient than to a sprawl of cul-de-sacs full ofsemi detached houses.

The Environmental Change Institute reporting to the RoyalCommission on Environmental Pollution ( RCEP) concluded thathigh density development of smaller dwellings within existingurban environments reduces ‘ greenfield take’ makes better use ofexisting infrastructure, whilst recognising the increasing demandfor single person dwellings. (ECI 2006)

Limitations:It would be wrong however, not to point out at this time, theparticular limitations of the science in this chapter.

The data for embodied energy from Bath University is by their ownacknowledgement, just a collection of information from varioussources with different methodologies underlying them.

Having looked at some of the primary sources behind the ECI tableof the embodied energy in new build, it is difficult to be confidentthat these are based on strong analysis.

Further detail could be added to the calculations of embodiedenergy in Normandie Tower.

Appropriate urban density is complex area of research that has onlybeen touched on here.

There is further work to do here, but a methodology is suggested andthere are good reasons and sufficient margins to be confident in theoverall findings of the chapter.


10. Summary andConclusions

Summary

This piece of work attempted to assess the environmental credentials of highrise residential blocks in a country that is generally hostile to the style ofarchitecture, but needs to face up to hard decisions about housing put upon itby the exigencies of climate change and ‘Peak Oil’.

How successful has it been?

The three most important pieces of work in this particular area of study, TheSustainable Tower Blocks Resource, The National Sustainable Tower BlocksInitiative, and Euroace were looked at to ensure that this piece of work wouldadd to the available literature and not duplicate it.

Of the three, only The Sustainable Tower Blocks Resource makes a start in thedirection that this thesis tried to go. Useful and interesting as it is however, it is asource of ideas, and not of analysis. This thesis has made its own contribution,not only by increasing understanding of the significance and context of existinghigh rise dwellings, but also by providing the outlines of an analytical tool forbuilding owners.

Chapter three provided a factual base for the rest of the piece, and questionedsome of the most common preconceptions about high rise blocks – those beingthat the high rise concept was ill conceived and that high rise buildings werebadly designed, badly built and in poor condition.

The section about Modernism demonstrated the high ideal and, in some cases,successful execution of the architectural concept. Modernist architecture, ofwhich the high rise block was an important part, replaced very poor housing andthe new occupants were for the most part impressed and satisfied by their new‘communities in the sky’. It went on to describe how that ideal had beencorrupted by the political and economic imperatives of the time, and that gooddesign and high ideals became compromised by speed of execution, andsubsequently by a lack of understanding and resources to manage the hugesocial experiment that housing had become.


The next two sections of this chapter then looked at the way high rise blockswere built and at their current condition. This was primarily descriptive, in orderto contextualise the later analysis, but also concluded that high rise blocks,although in need of internal refurbishment and concrete repairs, were generallyfit for purpose and remain in a basically sound condition. Demolition on thegrounds of condition, has generally been a smoke screen for building ownerswith overwhelming estate management problems.

Chapter four described why the issue is important and how hard decisions arenecessary. Climate change is a reality. Housing contributes almost a third to thecarbon dioxide emissions of the UK, and high rise represents a significantproportion of housing. Housing is in short supply and poor condition andinvestment in it is far too small. In order to address the climate change andhousing issues therefore, a debate is needed about where to refurbish andwhere to demolish and rebuild. The emphasis in the selection of which buildingsto demolish and replace will have to shift towards the most energy inefficient.

Chapter five looked at the poor understanding the UK has about its housingstock, and concluded that the country’s approach to energy efficiency in theexisting stock is naive, being based on misunderstanding and an out of dateappreciation of what is needed to achieve the energy savings required by thissituation. Available data was analysed and the chapter concluded that, on thebasis of the evidence, the labelling of high rise dwellings as ‘Hard to TreatHomes ‘ is misplaced and an example of this misunderstanding.

Three case studies from primary research and three from secondary sourcesare included in chapter six, together with a review of demolition numbers. Theylook at the approach building owners are taking to the issue, aid analysis ofheat loss from particular building types and inform the later chapters.

It is evident for the English examples, that energy efficiency is not a primarydriver in doing refurbishment work. Where energy performance improvementsare made, they are done either for political gain or are ancillary to cosmeticimprovements already proposed. Even in the case of the Little Venice projectthere is a surprising omission of the application of standards and scientificprinciples, preferring instead a ‘hit and hope’ approach. Budgets and a lack ofurgency about energy efficiency seem to drive the agenda for these works. Theinfrequent opportunity to carry out energy efficiency works, presented by theerection of access equipment to carry out the repairs, is being routinely missed.

The thermal performance analysis, by observation and the use of IES VEthermal simulation software, of Normandie Tower in Norwich is discussed inchapter seven to establish what relative improvements can be made through theintroduction of external insulation and double glazing.

There was some discrepancy between the results and the actual fuel use, andthe suspicion remains that the overall level of results obtained from thecomputer modelling was optimistic. However, the modelling proved pertinentnevertheless, and the relative improvement in performance of the block wasimpressive. Informed observation confirms that high rise flats should perform


well as they benefit from a simple form and the buffer effect of each other andthe common areas to keep them warm.

Chapter eight studied the practicalities of improving the thermal performance ofhigh rise blocks, paying particular attention to the basics of insulation anddouble glazing, and to the particular and relevant differences they have to otherconstruction types. Whilst the height of these blocks requires expensive accessequipment and results in extremes of weather, the relatively simple form andaesthetic of the tower block is conducive to the fitting of external insulation anddouble glazing without much practical difficulty or objection.

The impact of refurbishment and demolition and new build on the environment,green field sites and urban density was then looked at in the chapter nine. Itconcluded that, if the performance assured by the earlier analysis could be met,the refurbishment option was significantly more energy efficient over the lifetimeof the building than demolition and rebuilding.

It also concluded that high urban densities are key to efficient resource use.Urban densities can remain high and still be successful with good design, but inmost cases demolition and replacement of the dwelling is likely to at leastdouble the land use for the same number of dwellings.

Further Research

To undertake research of this sort is to realise the frailty and novelty of thisbranch of science and policy. There is much research to do in this area, and alot of it will only be done when the political and financial backing is provided.

The urgency of the debate continues to increase, and the parameters change.

The housing stock is badly understood. The data may be there, but adequateanalysis for energy assessment purposes has not been done. Classification ofdwelling types as ‘hard to treat’ on the basis of whether there are lofts andcavity walls, is simply not adequate for the challenge that lies ahead.

Some basic scientific parameters are still unclear in this debate. In the earlyBRE case studies, energy improvements were measured in terms of fuel coststo occupants. Now, building energy is analysed in terms of SAP ratings, kWhper metre squared, and kWh per dwelling, and there is still no consistencyabout methods of carbon accounting. This makes comparison and analysisdifficult.

Embodied energy of building materials and installations is a subject that iswidely debated in these discussions, but the implications seem to be largelymisunderstood. There is little surprise in this when there is so little reliable basedata on the subject.

Whilst the detailed analysis of the energy use at Normandie Tower would beinvaluable in any debate about investment in it, there is scope to harden up the


findings, both in terms of the inputs to the model and of prolonged study of theways in which the occupants use the dwellings.

To apply the findings of this analysis to all other locations would be to presumetoo much. The findings have a general significance for high rise blocks, butmostly present a useful methodology for understanding each one, as the needarises. The results themselves are only reasonably accurate for this one towerblock and even then form only part of the equation.

Conclusions

There is a resurgence of interest in high rise living - and no wonder. Althoughthe housing experiments of the 1950’s and 1960’s failed in so many ways, theconcept of high rise living fits the times well now and, apart from building newtower blocks, a thorough reappraisal of our existing blocks is necessary in thecurrent context.

This is an emotive issue. Many will argue that it is simply inhuman to crampeople together in a tall building, but demand for inner city high rise apartmentsbelies this assertion. This work has not sought to deny the importance of socialfactors in decisions about demolition and refurbishment, merely to raiseenvironmental issues up the agenda and provide a framework to discuss them.

Resource use, security, provision of facilities and, as has been demonstratedhere, the potential for energy efficient living, must favour the high densityenvironments provided by residential high rise. The demonstrable potentialenergy reduction for space heating and the impacts on land and resource use ofdemolition provide a strong case for the energy efficient refurbishment of highrise blocks.

Building owners are still continuing to favour demolition over refurbishment, andeven where refurbishment is being done, once in a lifetime opportunities tocarry out energy efficient improvements to high rise blocks are being spurned.

There are many reasons for this. There is a lack of urgency in introducingenergy efficiency measures in to the existing housing stock generally; there is apolitical and economic bias towards new build over refurbishment; and finally,there is a lack of understanding of the issues by building owners, who in anyevent, are routinely under funded for investment in their stock.

Decisions about refurbishment or demolition of high rise buildings will continueto be local ones in which local conditions prevail. Town by town, and block byblock, social, climatic, structural, architectural and economic circumstancescontribute to these decisions. All that is required is that decision makers arearmed with the right tools to make the right decisions, and the right toolsincludes an energy performance assessment in the context of a changingclimate.

__________________ oo __________________


Appendices

Appendix 1: Normandie/ Winchester Tower Construction Details

Appendix 2 : Normandie / Winchester Tower Floor Plans

Appendix 3 : Tower Block Modelled variables for IES simulation

Appendix 4 : Oil consumption figures for Winchester Tower


Appendix 1 :

Table 42: Normandie and Winchester Towers , Norwich. Existing Construction details

.General description 16 storeys

95 flats ( 6 per storey with 5 on the ground floor)

four 2 bed flats and 2 i bed flats o each storeycentral core with services , lift, stairs and access corridors to flats

Walls (External tointernal)

Material Thickness 1

Pebble dash 10mm

External render 25mm

‘No fines’2 Concrete 300mm

Glass Fibre Quilt 50mm

Plasterboard 13mm

Plaster 5mm

Total 403mm U Value3 of 0.5397

Floors Dense cast concrete 250mm

Windows4 PVCu Double glazed 4mmGlass8mm Cavity

Flat Roof 3 layer bitumen felt 15mm

Ply 25mm

fibreglass 100mm

dense concrete slab 150mm

Plaster 13mm

Total 300mm U Value 0.3341

Internal Walls Plaster 13mm

Cast Concrete 130mm

Plaster 13mm

Total 156mm U Value 2.3041

Dimensions Area m2 Height m Volume m3

Flat 1 (2Bed) 62.4 2.4 149.76

Flat 2 (2Bed) 54.4 2.4 130.56

Flat 3 (1Bed ) 36.96 2.4 95.90

Flat 4 (1Bed ) 36.96 2.4 95.90

Flat 5 (2Bed) 55.08 2.4 132.19

Flat 6 (2Bed) 56.8 2.4 136.32

Total Floor Area 5760m2

External wall area 3265

Exterior opening area 924m2

1 Dimensions are measured , taken off plan , or in exceptional cases , presumed

2 See Glossary

3 EN-ISO U Values as calculated by IES on the back of conductivity figures from CIBSE Guide A( see Ref)4 Windows were originally timber single glazed, but were replaced in about 1985 with doubleglazed PVCu.


Appendix 2 :

Figure 24: Ground Floor Plan of Winchester Tower

This is the identical ‘sister‘ block to Normandie Tower


Appendix 3:

Table 43: Tower Block modelled variables for IES VE simulations

Model 1 --- As built

Walls Construction 1 U = 0.5397 Original. See ‘constructiondetails’ for makeup of walls

Windows

Glazing 1 U= 5.2237 4mm single glazed

Air infiltration First 3.0 ach Original

Model 2 - As existing (with 1985 replacement windows)

Walls

Construction 1 U= 0.5397 Original. See ‘construction

details’ for makeup of walls

Windows

Glazing 2 U= 2.8643 Existing Double glazed 4mmglass , 8mm cavity , 4mm

glass

Air infiltration Second 2.0 ach

Model 3 – As existing plus external insulation

Walls Construction 2 U = 0.2783 Externally insulated walls

Windows

Glazing 2 U= 2.8643 Existing Double glazed 4mmglass , 8mm cavity , 4mm

glass

Air infiltration Third 1.0 ach

Model 4 – As existing plus 2006 Double glazing

Walls Construction 1 U = 0.5397 Original. See ‘construction

details’ for makeup of walls

WindowsGlazing 3 U= 1.9698

Air infiltration Fourth 0.7

Model 5 – Added External Insulation plus 2006 Double glazing

Walls Construction 2 U = 0.2783 Externally insulated walls

Windows

Glazing 3 U= 1.9698

Air infiltration Fifth 0.4 ach


Appendix 4

Table 44: Oil consumption for Winchester Tower, Norwich.

Oil Consumption

Date 05/06 Consumption Cost

(litres) (£)

05.04.2005 7,000 2,104.20

12.05.2005 7,009 2,106.90

13.06.2005 6,200 1,949.28

18.07.2005 5,000 1,574.50

15.08.2005 5,219 1,772.37

19.09.2005 7,000 2,420.60

28.10.2005 7,000 2,522.10

17.11.2005 7,150 2,431.72

31.11.2005 6,980 2,346.68

15.12.2005 7,000 2,443.00

22.12.2005 7,038 2,373.21

03.02.2006 7,006 2,380.64

12.01.2006 7,130 2,510.47

17.02.2006 7,120 2,503.39

03.03.2006 7,178 2,500.10

17.03.2006 10,724 3,809.16

Total 111,754 £ 37,748.32

Average Unit Cost (p/litre) 0.338

kWh 1,184,592.40 3.2 p/kWh


Bibliography

Abbreviations / Glossary

Bredem definition from Building Research Establishment General Information Sheet 31. fromhttp://www.ihsti.com/tempimg/B98864-CIS888614800201832.pdf accessed 04.01.08

Decent Homes programme defined with the aid of the Department of Communities and LocalGovernment at http://www.communities.gov.uk/housing/decenthomes/whatis/ accessed04.01.08

HECA definition from Defra http://www.defra.gov.uk/environment/climatechange/uk/publicsector/localauth/heca95/index.htm accessed 04.01.08

Non traditional Construction defined with help from National Centre For Excellence in Housingat http://www.homein.org/page.jsp?id=543 accessed 03.01.08

PassivHaus definition with help from PassivHaus UK. from http://www.passivhaus.org.uk/accessed 03.01.08

Retscreen from www.retscreen.net accessed 04.01.08

ROCS definition assistance fromhttp://www.ofgem.gov.uk/Sustainability/Environmnt/RenewablObl/Pages/RenewablObl.aspxaccessed 03-01-08

SAP definition with assistance from Building Research Establishment athttp://projects.bre.co.uk/sap2005/ accessed 03.01.08

U Value definition from Clear at :http://www.learn.londonmet.ac.uk/packages/clear/thermal/buildings/building_fabric/properties/transmittance.html accessed 03.01.08

Warm front definition from www.warmfront.co.uk accessed 07.01.08

1. Introduction:

Department of Communities and Local Government.(2005) English House Condition Surveyfrom http://www.communities.gov.uk/housing/housing research/housing surveys/ english housecondition/ Accessed 08.07 to 01.08

Euroace. http://www.euroace.org/highrise/index.htm. Accessed. 09-07 to 01-08

Eso News http://eso-news.blogspot.com/2007/10/oliennes-sur-le-world-trade-center.htmlAccessed 12.01.08

2. Literature Review

Sustaining Towers Resource: http://www.sustainingtowers.org/ (Accessed 09-07 to 01-08)

National Sustainable Tower Block Initiative (NSTBI) from http://www.towerblocks.org.uk/html(Accessed 09-07 to 01-08)


Gale T, and Church C (2000). Streets in the Sky. Towards improving the Quality of life in Towerblocks in the UK. The First Report of the National Sustainable Tower blocks initiative. Availablefrom NSTBI http://www.towerblocks.org.uk/html ( Retrieved 12-10-2007 )

Euroace . http://www.euroace.org/highrise/index.htm. Accessed. 09-07 to 01-08

IES VE. Software downloaded from IES www.iesve.com. April 2007

Build Desk 3.2. U Value Calculator software. Download from Build Desk Ltd. September 2007.

Roaf S, Crichton D, Nicol F. (2005) Adapting Buildings and Cities for Climate Change. Elsevier /Architectural Press. Oxford

Glendenning M and Muthesius S. (1993). Tower Block. Modern Public Housing in EnglandScotland and Northern Ireland.Yale University Press for the Paul Mellon Centre for Modern British Studies in Art.

Open University. From here to Modernity. ( Accessed October 2007)http://www.open2.net/modernity/

Jencks.C. (2000) Le Corbusier and the Cultural Revolution in Architecture. Monacelli Press.

Abercrombie. P. (1945). The Greater London Plan 1944: London HMSO

Concrete Today. The Cement and Concrete Association Jul – Sept 1951 Living in Flats .Sourced via the Concrete Society http://www.concretecentre.com/PDF/cq_011.PDF. AccessedSept 2007

3. Understanding High Rise Buildings

Glendenning M and Muthesius S. (1993). Tower Block. Modern Public Housing in EnglandScotland and Northern Ireland. Yale University Press for the Paul Mellon Centre for ModernBritish Studies in Art.

Open University (No date) . From here to Modernity. ( Accessed October 2007)http://www.open2.net/modernity/

Jencks.C. (2000) Le Corbusier and the Cultural Revolution in Architecture. New York. MonacelliPress.

Unite D’habitation from Great buildings on line http://www.greatbuildings.com/cgi-bin/gbi.cgi/Unite_d_Habitation.html/cid_2464522.html. Accessed 12.01.08

Abercrombie. P. (1945). The Greater London Plan 1944: London. HMSO

Concrete Today . The Cement and Concrete Association Jul – Sept 1951 Living in FlatsSourced via the Concrete Society http://www.concretecentre.com/PDF/cq_011.PDF accessed06.08.07

Glick D H and Reeves B R (1996) Building Research Establishment Report. The structuralcondition of cast-in-situ concrete high-rise dwellings. Garston. Building ResearchEstablishment.

Williams A.N and Ward GC (1991). The Renovation of Wimpey No Fines Housing. Garston.Building Research Establishment.

BRE (1985). The Structure of Ronan Point and other Taylor Woodrow - Anglian buildings.Garston. .Building Research Establishment.

Build Desk 3.2. U Value Calculator software. Download from Build Desk Ltd. September 2007.


Hotchkiss A.R and Edwards MJ . (1988) Bison Large Panel System Dwellings: Constructionaldetails . Garston. Building Research Establishment.

CIBSE (1999) Guide A Environmental Design . London. Chartered Institute of BuildingEngineers.

The Department of the Environment (DOE) (1996) Good Practise Case Study 121. EnergyEfficient Refurbishment of High Rise LPS dwellings. Garston.

Building Research Establishment.

Rouse and Delatte (2003) Lessons from the Progressive Collapse of the Ronan Point ApartmentTower, Proceedings of the 3rd ASCE Forensics Congress, October 19 - 21, 2003, San Diego,Californiahttp://www.eng.uab.edu/cee/faculty/ndelatte/case_studies_project/Ronan%20Point.htmAccessed 21.08.07

Wearne, Phillip (2000). Collapse: When Buildings Fall Down. TV Books, L.L.C., USA. viahttp://www.eng.uab.edu/cee/faculty/ndelatte/case_studies_project/Ronan%20Point.htmAccessed 21.08.07

Davis Langdon & Everest (2002) Refurbishing a Tower Block, Cost model, From Issue 49 ofSocial Housing: December 2002 viahttp://www.building.co.uk/story.asp?sectioncode=113&storycode=1024090&c=

Ciria (1992) Special Publication 87 . Wall technology. Volume E. Large Heavy units on framed

buildings and in situ Concrete. London .Ciria

Currie R J, Reeves B R, Moore J F (1987) BRE report A .The structural adequacy and durabilityof large panel system dwellings. Garston, Building Research Establishment

Department of Communities and Local Government.(2005) English House Condition Surveyfrom http://www.communities.gov.uk/housing/housing research/housing surveys/ english housecondition/ Accessed 08.07 to 01.08

Brookes. A (1998) Cladding of Buildings . London. Spon .

4. Environmental, Social and Legislative context

Summary for Policymakers of the Synthesis Report of the IPCC Fourth Assessment ReportDRAFT COPY 16 NOVEMBER 2007 23:04 – Subject to final copyedit.http://www.ipcc.ch/pdf/assessment-report/ar4/syr/ar4_syr_spm.pdf Accessed 20.11.08

Dti. (2003). Energy White Paper – Our Energy Future – Creating a Low Carbon EconomyNorwich. HMSO

Department of Communities and Local Government (2007)http://www.communities.gov.uk/index.

Department of Trade and Industry via The House of Lords Select Committee on Science andTechnology – Second Report 2005http://www.publications.parliament.uk/pa/ld200506/ldselect/ldsctech/21/2106.htm

Helweg-Larsen et al. (2007) Zero Carbon Britain. Machynlleth. Centre for AlternativeTechnology.

Kate Barker (2004) Review of Housing Supply . (Delivering our stability : securing our futurehousing needs). at :http://www.hm-treasury.gov.uk/media/053/C7/barker_review_execsum_91.pdf


Constructing Excellence via Stock Take (2006)http://www.sd-commission.org.uk/publications/downloads/Stock_Take_UK_Housing.pdf.Accessed 08.09.07

XCO2 (2002) Insulation for Environmental Sustainability A Guide . London XCO2 Conisbee

Environmental Change Institute. (2007) Reducing the Environmental Impact of Housing Finalreport – Appendix E. Oxford. Environmental Change Institute

Boardman B,. et al (2005). 40% House . Oxford. Environmental Change Institute

5. Classification and comparison

Energy Savings Trust 1http://www.energysavingtrust.org.uk/housingbuildings/localauthorities/theguide/scotland/hard//

Energy Savings Trust 2 Best Practice in Housing . Hard To Treat Homes and Fuel Poverty.http://www.energysavingtrust.org.uk/housingbuildings/calculators/hardtotreat/

Energy Efficiency Partnership for Homes (Insulation Strategy Group and Hard-to-TreatSubgroup (2006) Final Report : Identifying and Quantifying the Prevalence of Hard to TreatHomes. From :http://www.eeph.org.uk/uploads/documents/partnership/HTTH%20Mapping%20Research%20Mar%2006.pdf (accessed 22/10/2007)

Centre for Sustainable Energy (March 2005). Fuel Poverty and Non Traditional ConstructionsPrepared for the HTT Sub-Group of the Energy Efficiency Partnership for Homes. Bristol. Centrefor Sustainable Energy. From :http://www.eeph.org.uk/uploads/documents/partnership/HTTH%20Mapping%20Research%20Mar%2006.pdf (accessed 23/10/2007)

Energy Savings Trust Information team . 21/02/2006 from http://www.energysavingtrust.org.uk/accessed 20th December 2007

UK Fuel Poverty Monitor.(2006) Separate but Unequal . Energy Efficiency standards in socialhousing in the United Kingdom. Third Year report . From:http://www.nea.org.uk/downloads/publications/Fuel_Poverty_in_Social_Housing_in_the_United_Kingdo1.pdf. Accessed September 2007

6. Case studiesJohn Prescott to the Better Buildings Summit quoted by ‘ Enabling Concepts’ at :http://www.enablingconcepts.co.uk/testimonials.html

Wates Construction Limited fromwww.wates.co.uk/living_space/living_space_projects/glastonbury 16/11/2007

Makartstrasse Flats information from Nachhaltig Wirtschaften. www.etn.wsr.ac.at/(en)/rxml/results accessed 10.12.07

Makartstrasse Flats Photographs from Gap Solar at http://www.gap-solar.at/beitraege/downloads/2006_%20Projektbericht%20Makartstra%C3%9Fe%20Linz_1012.pdf. accessed 10.12.07

Euroace : Energy Efficiency in High Rise Refurbishment Case Study Series. www.euroace.com

Interviews 9th October 2007 : Anthony Dickens – and Prija of Wates Construction.


Various correspondence by e mail with Martyn Kemp and Ken Lee of Kemp Muir Weallansbetween October 2007 and January 2008.

Information obtained from site visit and interviews with Apollo Construction, and Homes forIslington. 8

th October 2007

Norwich City Council Interviews October 2007

UK Housing Wiki at http://ukhousing.wikia.com/wiki/Category:Demolished_tower_blocks,accessed 08.01.08

7. Analysis of heat loads in high rise residential buildingsCIBSE (1999) Guide A Environmental Design . London. Chartered Institute of BuildingEngineers

Fuel Prophet : from Association for the Conservation of Energy athttp://old.ukace.org/research/fuelprophet/index.htm. Downloaded 08.07.

8. Improvements to thermal performance. Potentials and Practicalities

Colwell S and Martin B ( 2003) . Fire Performance of External Thermal Insulation for walls ofMulti Storey Buildings. Garston. Building Establishment.

Swiss Lab BBA certificate 2001 BBA

Trim MJB (1991) BRE information paper. Improving the Energy efficiency Performance of Highrise flats . Garston .Building Research Establishment

Technical literature from Sto Ltd, Permarock Ltd , Alumasc and Weber Ltd

Energy Savings Trust (Feb 2004) Energy Efficient Best Practice in Housing Community HeatingAberdeen City Council Case study. London. Energy Savings Trust.

Ashden Awards from http://www.ashdenawards.org/winners/barnsley. accessed 30.11.07

Sandwell PV information from :http://www.savenergy.org/pdf/Bowater%20House.pdf accessed06.08.07.CIS tower information from : http://www.cis.co.uk/servlet/Satellite?cid=1116834043935&pagename= CoopBank/Page/tplBlank&c=Page. Accessed 30.11.07

Retscreen software from www.retscreen.net accessed 04.01.08

Energy for Sustainable Development Ltd (2003). Bradford Tower Block Wind Energy FeasibilityStudy. Downloaded from http://www.clear-skies.org/CaseStudies/Documents/2121485.pdf.December 14

th 2007

Bradford High Rise Wind Turbines from: http://www.yorkshirepost.co.uk/localnews/Wind-turbines-on-tower-block.1202132.jp. Accessed 02.12.07

9. The environmental impact of demolition, replacement andrefurbishment of high rise blocks.

Bath University Sustainable Energy Research Team (No date). Inventory of Carbon and Energy,downloaded from http://people.bath.ac.uk/cj219/ September 2007

Environmental Change Institute (2007) . Reducing the Environmental Impact of Housing Finalreport – Appendix E University of Oxford Embodied energy. Accessed 09.07 to 01.08


Ireland D (Empty Homes Agency). (no date) Blue Prints for Green Homes. Energy Policy for the21

st Century http://www.emptyhomes.com/documents/publications /Blueprints%20for%20

Green%20Homes.pdf. Downloaded Nov 27 2007

Specification from Permarock Ltd : Permarock Mineral Fibre 2006

Bioregional – Bedzed energy standardshttp://www.bioregional.com/programme_projects/ecohous_prog/bedzed/bz_monitoring.htmaccessed 14.12.07

AECB Energy standards : Page 3http://www.aecb.net/PDFs/carbonlite/AECB_VOL_3_EnergyStandard_V4c_FINAL.pdf Accessed14.12.07

Society Guardian (25.06.2003). Livingstone attacks low density Housinghttp://politics.guardian.co.uk/homeaffairs/story/0,,984783,00.html Accessed 03.01.08

Society.guardian.co.uk/urbandesign/image/0,11200,765683,00.html - 32k –20.07.02 . Accessed03.01.08

CABE: http://www.cabe-education.org.uk/buildingforlife.aspx?bfl=true&contentitemid=340&aspectid=24 . Accessed 03-01-08

Planning Policy Statement 3fromhttp://www.communities.gov.uk/documents/planningandbuilding/pdf/planningpolicystatement3 . Accessed 03.01.08

Rogers R (2003) Housing for a Compact City . London. Greater London Authority.

Palmer J, Boardman B et al (March 2006) Reducing the Environmental Impact of Housing FinalReport Consultancy . Study in support of the Royal Commission on Environmental pollution’s26th

Report on the Urban Environment. Environmental Change Institute

XCO2 (2002) Insulation for Environmental Sustainability A Guide . London. XCO2 Conisbee

WRAP (No date) The Demolition Protocol . Aggregates Resource Efficiency in Demolition andConstruction. Wrap London.