reference buildings for cost-optimal analysis · reference buildings for cost-optimal analysis...

REFERENCE BUILDINGSFOR COST-OPTIMAL ANALYSIS

Bruxelles, March 8, 2012S.P. Corgnati*, E. Fabrizio§, M. Filippi** Politecnico di Torino § University of Torino

WHY REFERENCE (BENCHMARK) BUILDING MODELS ?

COST OPTIMAL POLICY of the EPBD (European Performance ofBuildings Directive) recast 2010/31/EU for the definition of thetargets of nearly-zero energy buildings.Draft working document on supplementing Directive 2010/31/EU1. Selection of reference (benchmark) buildings2. Definition of energy saving measures for construction3. Definition of energy saving measures for technical systems4. Energy calculations (energy requirements)5. Economic calculations (global cost)6. Sensitivity analyses and finding of the cost-optimal valueWhat are nearly-zero energy buildings?

REFERENCE BUILDINGS FOR COST-OPTIMAL ANALYSIS

1.

2. & 3.

4.

6.

The methodology

5.

What is a Reference Building?REFERENCE BUILDINGS FOR COST-OPTIMAL ANALYSIS

Step 1Reference BuildingsStep 1Reference Buildings“building characterized by, and representative of, their functionality and

geographic location, including indoor and outdoor climate conditions”

[EPBD recast-Guidelines]

Each Member State has todefine A SET OFREFERENCE BUILDINGS:- 2 for existing buildings;-1 for new construction.

Energy Performance ofBuildings DirectiveRecast (EPBD recast,2010/31/EU)

BUILDING CATEGORIES:- Single-family house;- Multi-family house;- Office building;- Non- residential buildings.

REFERENCE BUILDINGS FOR COST-OPTIMAL ANALYSISApproaches to a Reference Building constructionHandbook, manuals,

experience, references

Buildingstock Known building

stock

ExpertExample RB

Statisticalmanipulation

separatedresults

Real RB

….

Theoretical RB

aggregatedresults

Fictional buildingInput data

Processing Model

Problem of the true correlations


Approaches to a Reference Building Step 1Reference BuildingsStep 1Reference Buildings

REAL BUILDING: a real existing building, with average characteristics based onstatistical analysis.EXAMPLE BUILDING: On the basis of experts’ assumption it is the most probable of agroup of buildings, within a selected location and age.THEORETICAL BUILDING: A statistical composite of the features found within acategory of buildings in the stock (ECBS definition).

Empirical Data

Expert Assumptions

Statistical Data

Step 1Reference BuildingsStep 1Reference Buildings


ASSUMPTIONS:

1. System Boundary



ASSUMPTIONS:

2. Metrics

GLOBAL COST

consumableitems

cyclical regulatory cost

utilities(except energy cost)

global cost

initial investment cost

annual cost

disposal cost

running cost

professional fees (e.g. project design)construction of assetstaxes (if applicable)others (e.g. projectcontingencies)

energy cost

operational cost

maintenance cost

periodic substitute investmentof a building element

result ofenergy performance

calculation

energy tariffs

replacement cost

adjustmentsinspections

cleaningrepair

insurance

taxes (if applicable)others

consumableitems

cyclical regulatory cost

utilities(except energy cost)

global cost

initial investment cost

annual cost

disposal cost

running cost

professional fees (e.g. project design)construction of assetstaxes (if applicable)others (e.g. projectcontingencies)

energy cost

operational cost

maintenance cost

periodic substitute investmentof a building element

result ofenergy performance

calculation

energy tariffs

replacement cost

adjustmentsinspections

cleaningrepair

insurance

taxes (if applicable)others

Cost categorisation according to the FrameworkMethodology (EPBD guidelines)Standard EN 15459



ASSUMPTIONS:

2. Metrics

GLOBAL COSTLifecycleLong Lifecycle are notrecommended as it isdifficult to predict theinterest rates and energyprices. 50 years

Standard EN 15459

1)all the costs refer to the starting year by applying appropriate discount rate coefficientsor present value factors;2)the global cost is the sum of the global costs of initial investment costs, periodic andreplacement costs, annual costs and energy costs and the global cost of the final value(negative).

Discount rate?Real interest rate (2,5%)General inflation rate /Inflation rate of energysources /

Lifespan periods ofbuilding elements



ASSUMPTIONS:

3. The boundary conditions: constant parameters

ClimateBuildingenvelope

Buildingequipment

Operation &MaintenanceOccupantbehavior

IndoorenvironmentalconditionsBuilding Performance Energy Needs

STATE OF THE ART

World:Benchmark Building models developed by US Department of Energy (DOE)

Europe:-TABULA project on the definition of residential building typology for energy investigations;-ASIEPI project- BPIE Principles for nearly-zero energy buildings (single-family house, multi-storey building)-Rehva Task Force: “Reference Building for energy performance and cost optimal analysis”.



Principles and Application fields of TABULA project Collected national representative single-family houses by ASIEPI project

RESEARCH ACTIVITIES BY TEBE GROUPDefinition of three Reference Buildings:REFERENCE BUILDINGS FOR COST-OPTIMAL ANALYSIS


A Multi-family residential building (Source: TABULA project)A Medium Office Building (Source: ENEA survey over the definitionof a representative Italian office building for three main areas)A Large Office Building as result of a customization of the DOE large officebuilding to Italian context (legislative requirements, constructions, climate)Reference buildings collected by age:

1 23



MULTI-FAMILY REFERENCE BUILDING

Typical floor plan, Multi-family building.

BUIL

DIN

G

Geometry

External dimensions 12,60 x 37,50 mGross Floor Area 472,50 m2Total Gross Area 1336 m2Room height 3,10 mN-E Façade Exterior wall area 170,10 m2S-E Façade Exterior wall area 383,70 m2Window area 122,58 m2S-O Façade Exterior wall area 170,10 m2N-O Façade Exterior wall area 326,30 m2Window area 94,06 m2

EnvelopeComponents

Opaque elements Exterior Wall 0,52 W/m2KFlat ceiling under the roof 2,02 W/m2KSlab towards non conditionedbasement 1,35 W/m2KTransparentElements Window 3,51 W/m2K

SYST

EM

Heatingsystem

Gas boiler with radiators.The setpoint temperatures are 20°C from 7 a.m. until 8 p.m., and18°C during the remaining hours.Ventilation The infiltration rate is 0,5 ACH and is constant during all days.

OPE

RATI

ON

Internal Gains

People 0,04 person/m2Appliance (incl. Lighting) 4 W/m2

RealBuilding



MEDIUM OFFICE REFERENCE BUILDINGBU

ILD

ING

Geometry

External dimensions 16x30 mGross Floor Area 480 m2Total Gross Area 2400 m2Height 2,9 mNorthern Façade Exterior wall area 278 m2Window area 157,50 m2Southern Façade Exterior wall area 278 m2Window area 157,50 m2Western Façade Exterior wall area 232 m2Window area 140 m2Eastern Façade Exterior wall area 232 m2Window area 140 m2Envelope

Components

Opaque elements Exterior Wall 0,761 W/ m2 KRoof 0,828 W/ m2 KUnderground slab 0,516 W/ m2 KTransparent Elements Window 3,19 W/ m2 K

SYST

EM

HVAC 4 pipes fancoils with outside airHeating system Gas boiler (80°C)

Heating setpoint21,5°C from 5 a.m. until 6 p.m., and 15°C in remaining hours, duringweek days.

Cooling system Water-cooled chillerCooling setpoint

26°C from 5 a.m. until 6 p.m. during week day;Turn off during the remaining hours.Ventilation

11 l/s per person,Air flow is assumed to be constant from 5 a.m. until 6 p.m during weekdays.

OPE

RATI

ON

Internal Gains

People The occupancy rate for offices id 0,06 person/m2.Lighting 13 W/m2 during working days. A 0,5 percentage is assumedduring weekends and night time for security systems.Equipment 10 W/m2 during working days.

Axonometric View, Medium office building.

Typical floor plan, Medium office building.

TheoreticalBuilding



LARGE OFFICE REFERENCE BUILDING

Axonometric View, Large office building.

Thermal zones, Large office building.

ExemplarBuilding

BUIL

DIN

G

Geometry

External dimensions 48x73 mGross Floor Area 3563 m2Total Gross Area 46’320 m2Floor to Floor Height 2,74 mNorthern Façade Exterior wall area 2090 m2Window area 1391 m2Southern Façade Exterior wall area 2090 m2Window area 1391 m2Western Façade Exterior wall area 1389 m2Window area 927 m2Eastern Façade Exterior wall area 1389 m2Window area 927 m2Envelope

Components

Opaque elements Exterior Wall 0,309 W/ m2 KRoof 0,248 W/ m2 KUnderground slab 0,638 W/ m2 KTransparent Elements Window 1,1 W/ m2 K

SYST

EM

HVAC Multi-zone VAV with fancoilsHeating system Gas boiler (80°C)

Heatingsetpoint

21°C from 5a.m. until 7p.m., and 15,6°C in remaining hours, during weekdays.Cooling system 2 Water cooled chillers

Cooling setpoint24°C from 5 a.m. until 6 p.m. during weekdays; 30 °C during the remaininghours.

Ventilation0,10 ACH.Air flow is assumed to be constant from 6 a.m. until 10 p.m during weekdays.

OPE

RATI

ON

Internal Gains

People The occupancy rate for offices id 0,06 person/m2.Lighting 15 W/m2 during weekdays.Equipment 10 W/m2 during weekdays.


Step 2&3MeasuresStep 2&3Measures

PACKAGES OF MEASURES Multi-familyReferencebuilding

10 PACKAGES OFMEASURESconcerning thebuilding envelopeNON-HOMOGENEOUSPACKAGES: measuresregarding only to a fewbuilding elements.

HOMOGENEOUSPACKAGES: measuresapplied similarly to allbuilding elements.


EXTERIOR WALLTHERMAL

INSULATION


Multi-familyReferencebuilding

Standard Requirement PackageEnergy saving measure datasheet:




ECONOMICEVALUATION

OF THEMEASURE


Step 5Energy ModelStep 5Energy ModelDYNAMIC ENERGY

SIMULATION


EnergyPlusModeling

Simulation Results

Thermal zones

Input data


SIMULATION RESULTS:HEATING ENERGY DEMAND


020,00040,00060,00080,000

100,000120,000140,000160,000180,000

0 1 2 3 4 5 6 7 8 9 10

kWh

Package of Measures

Heating demandEnvelope lossesVentilationlosses

Step 5Energy ModelStep 5Energy Model


Step 6Cost Optimal AnalysisStep 6Cost Optimal AnalysisCOST-OPTIMAL LEVEL:

(with appliances) (without appliances)

Multi-familyReference building

300350400450500550600

0 25 50 75 100 125 150Primary energy [kWh/m2]

RB12345678910300

350400450500550600

0 25 50 75 100 125 150 175

Glob

al C

ost

[€/m

2]

Primary energy [kWh/m2]

REFERENCE BUILDINGS FOR COST-OPTIMAL ANALYSISOPEN QUESTIONS- How to select the packages of energy saving measures. With n differentmeasures that have k steps of varition, the number of combinationsbecomes knNot all the combnations of measures are feasible! The number reduces.- How to select the correct economic scenario that affects the global costcalculation:inflation rateinflation rate of energy sourcesinterest/discount ratelifetimesglobal lifespan- How take into account the spatial variability (locations, climate)


REFERENCESBallarini, I. Corgnati, S.P. Corrado, V. Talà, N. Definition of building typologies for energy

investigations on residential sector by TABULA IEE-project: application to italian casestudies, In: RoomVent 2011, Trondheim, 19-22 June 2011.Ballarini I., Corgnati S.P., Corrado V., Tala' N. (2011) Improving energy modeling of largebuilding stock through the development of archetype buildings., In: Building Simulation2011, Sydney (Australia), 14-16 November 2011. pp. 2874-2881E. Fabrizio, D. Guglielmino, V. Monetti, Italian benchmark building models: the officebuilding, in V. Soebarto, H. Bennetts, P. Bannister, P.C. Thomas, D. Leach (a cura di), “Drivingbetter design through simulation”, IBPSA Australia & AIRAH, Melbourne, 2011, pp. 1981-1988 (ISBN 978-0-646-56510-1).C. Becchio, D. Guglielmino, E. Fabrizio, M. Filippi, Whole cost analysis of building envelopetechnologies according to the European Standard EN 15459, Climamed ’11 VI CongresoMediterraneo de Climatizacion, Madrid 2-3 giugno 2011, ATECYR, pp. 291-306 (ISBN 978-84-95010-41-4).

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