Low Impact Building (Housing using Renewable Materials) || Building physics, natural materials and policy issues
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Low Impact Building: Housing using Renewable Materials, First Edition. Tom Woolley. 2013 John Wiley & Sons, Ltd. Published 2013 by John Wiley & Sons, Ltd.
Few people in the UK built environment field even recognise the importance of building engineering physics, let alone know how to apply the principles in the design of buildings. Building projects are traditionally led by architects, not engineers, but building energy performance hardly features in architectural education. This lack of essential knowledge to inform strategic design decisions has led to the perpetuation of an experimental approach to building performance, rather than an approach based on synthesis, rigorous analysis, testing and measurement of the outcome.
This statement from the Royal Academy of Engineering is an indictment of current built environment education in the UK. However, similar problems can be found throughout the world, in architecture and other built environ-ment disciplines. At the ARC-PEACE international conference in Copenhagen in April 2012, a resolution was adopted on the education of architects and planners:
We urge professional schools to develop curricula and train instructors to teach the architectural and planning skills necessary to create healthy, socially sustainable environments and create buildings and plan cities with smaller carbon footprints that reduce consumption and conserve energy.
It seems remarkable that in 2012, a group of architects and eminent profes-sors from all over the world, including Sweden, India, Peru, USA and Canada should find it necessary to call on universities and professional bodies to address socially responsible and ecological issues. Professional bodies such as the Royal Institute of British Architects and the International Union of Architects pay lip service to sustainability, but in practice many architecture schools have become art-house style and fashion centres that worship
6. Building physics, natural materials and policy issues
famous signature architects, few of whom have much concern for sustaina-bility. It is a worrying prospect for the future.
Despite this, there are many, often small, hardworking architecture and engineering practices that are strongly committed to environmentally pro-gressive design, but often they are swimming against the tide. They can be undercut by larger commercial firms whose commitment to sustainability rarely goes beyond greenwash. Those architects and engineers who want to push the boundaries of green and sustainable design are hampered by a lack of technical back-up, particularly in the area of building physics and building science. This is also a major problem for companies developing and selling natural renewable materials because current regulations and building science tools are biased in favour of petrochemical based materi-als and conventional approaches to building.
There are a number of areas of concern and topics discussed in this chap-ter including:
lack of good building physics understanding poor systems of assessing energy performance and a lack of attention
to thermal mass inadequate simulation and prediction tools weak government and EU policy directives on materials and buildings poor assessment of material environmental impact and performance lack of understanding of moisture and durability in buildings, breatha-
bility and hygroscopicity insufficient attention to health, pollution and indoor air quality issues.
A key principle of ecological building and design should be to adopt a holistic approach. In other words all important issues from energy use to environmental impact should be given equal consideration. As has already been discussed in Chapter 5, there are many experts who tend to focus on just one issue, such as operational energy, and downplay the impor-tance of other issues such as embodied energy or indoor air quality. However, to be truly committed to environmental responsibility many more issues other than energy efficiency should be given equal attention.
Also there is a complex interrelationship between external weather, internal humidity, and the nature of materials, ventilation, design and detailing. Unfortunately the agencies and areas of building scientific knowl-edge in this field are mostly compartmentalised and unrelated, leading to a poor understanding of how buildings actually perform in their totality.
Furthermore the use of natural and renewable materials is disadvantaged because conventional approaches to building physics and related environ-mental and energy science have been largely based on the perfor-mance of masonry construction and petrochemical based lightweight insulations. Regulations and building science methods are constantly
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evolving as technology changes, particularly as we move away from masonry to timber construction.
When the proponents of natural and renewable materials expound their advantages such as their good environmental performance, health and good indoor air quality, breathability, ability to handle moisture and humid-ity and an excellent thermal performance, these claims are not always backed up by enough solid data. Conventional wisdom and conventional architectural science is often used to discount these claims. Unless building physics theory and practice changes, the claimed benefits of renewable materials remain vulnerable to challenge by detractors.
It might be reasonable to expect that the principles of building physics would be based on good science and be independent of commercial vested interests but it soon becomes apparent that the discipline of build-ing physics is very weak in the academic sector and often driven by com-mercial funding. Universities and testing bodies in the UK are largely dependent on funding from industry. The lack of independent and critical science is self-evident when searching the literature.
In addition, over the past few decades, most of the changes in this area have been driven by regulations and compliance requirements that have not always been based on the best of science. For many years it was con-sidered sufficient for thermal performance to be regulated simply by pre-scribing levels of insulation. Then it was realised that insulation performance was weakened by air leakage and cold bridging. Various calculation meth-ods were introduced and strengthened as efforts were made to make buildings respond to the new agenda to reduce carbon emissions and reduce energy consumption. While these changes have been based on sci-entific advice, this has rarely been subject to proper independent analysis and has often driven more by pragmatic and political decisions.
Robust and then accredited details (Planning Portal 2012) were intro-duced but these are often inflexible, based on conventional building prac-tice and, in the view of some, unworkable. As discussed in Chapter 5, many of the attempts to achieve energy efficiency fail to work in practice.
More recently it has been understood, that issues such as thermal mass and the performance of materials in terms of moisture also play a big part, though this is barely recognised in many regulations and calculation meth-ods in the UK. Natural, renewable materials have important thermal mass and moisture handling characteristics, so as these become better under-stood and incorporated into regulatory systems, then natural and renewa-ble materials will be more readily accepted.
Increasingly designers are relying on computer simulation methods to predict the performance of buildings. These simulation tools rely largely on assumptions that are not always backed up with hard data, derived from real-time building performance. Indeed, it can be argued that there exists a parallel universe of experts sitting behind computers designing virtual build-ings and energy strategies that have almost nothing to do with real build-ings. These tools also have built-in assumptions that favour conventional materials and construction methods, though one or two like WUFI (Fraunhofer 2012) recognise the importance of moisture in buildings.
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As regulations and new tools have been overlaid on each other, over the years, fundamental errors of concept and science become reinforced and built into new systems. Assumptions and conventional thinking become accepted wisdom and are rarely tested in practice. Often these assump-tions are based on claims and data from industrial companies who are pro-moting their materials and products. These build commercially biased information into calculation tools. It is not uncommon to hear builders, specifiers and even building science experts, refer to generic materials such as breather membranes and foam insulations by the leading trade names such as Tyvek and Kingspan rather than their generic terms. This is symptomatic of the very pragmatic approach to specification and a ready acceptance of the technical information supplied by such companies. The bulk of continuing professional development (CPD) seminars attended by professionals are organised by commercial companies. This acts to the dis-advantage of natural renewable materials and products, as smaller and newer companies do not have the resources to do the promotion, profes-sional training and lobbying that the larger manufacturers of conventional products use.
European standards, trade and professional organisations
Organisations responsible for setting standards, carrying out tests and pro-viding technical guidance are rarely free of commercial pressures. Attempts by the European Union to introduce greater standardisation for materials quality and environmental performance have been balked for years by effective lobbying of European trade organisations. The EU Construction Products Directive was initially approved in 1988 and made clear that pol-lution issues were important. However, little has been done to enforce this objective:
Annex 1 Essential requirements 3. Hygiene Health and the environmentThe construction work must be designed and built in such a way that it will not be a threat to the health or hygiene of the occupants or neighbours in particular as a result of any of the following: the giving off of toxic gases the presence of dangerous particle or gases in the air the emission of dangerous radiation pollution or poisoning of the water or soil faulty elimination of waste water, smoke, solid or liquid wastes the presence of damp in parts of the works or on surfaces within the works
More recently the Construction Products Regulations have replaced the Directive and make provisions for CE marking of materials. However, they have not made Environmental Product Declarations (EPDs) compulsory andhave not specified that they should be third-party EPDs (in other words prepared by an independent assessment body). This is a result of
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conservative industry pressure to ensure that strong environmental stand-ards were not enforced and remain voluntary:
When a construction product is covered by a harmonised standard or con-forms to a European Technical Assessment, which has been issued for it, the manufacturer shall draw up a declaration of performance when such a prod-uct is placed on the market.
For the assessment of the sustainable use of resources and of the impact of construction works on the environment, Environmental Product Declarations should be used when available. (emphasis added)
Environmental lobbying at European level is relatively weak due to the high costs of gaining access in Brussels and Strasbourg, while large commercial companies and trade organisations are able to maintain permanent offices in Brussels. FIEC, the European Construction Industry Federation, for instance, has an office at Avenue Louise in the centre of Brussels, just down the road (also in Avenue Louise) is the European Insulation Manufacturers Association (EURIMA). The European Cement Association is a couple of streets away. Plastics Europe, part of the Global Plastics Federation is a bit more out of town, as is PU European the Polyurethane manufacturers association.
EU construction product regulations are managed through national gov-ernment agencies and they have not pushed very hard for stricter and inde-pendently enforced environmental controls. In the Zagreb statement calls were made for greater use of natural resources and recycling.
We think a requirement promoting the sustainable use of natural resources in construction works should be added into the future CPD. The sustainable use of resources can be enhanced; when an adequate product marking and appropriate design ensure that any hazardous substances in construction works can be easily separated for suitable treatment during demolition. Here European requirements to limit the presence of dangerous substances in con-struction products would make recycling easier.
However, the final regulations are very vague and weak in terms of resource consumption as there is no mention of non-renewable resources or embod-ied energy.
The construction works must be designed, built and demolished in such a way that the use of natural resources is sustainable and in particular ensure the following:(a) reuse or recyclability of the construction works, their materials and parts
after demolition;(b) durability of the construction works(c) use of environmentally compatible raw and secondary materials in the
construction works(EU 2011)
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Table 6.1 UK Organisations concerned with building and environmental standards
Organisation Status Interest in renewable materials
Building Research Establishment (BRE)
Private trust Set up the Centre for Low Impact Materials in Building (CLIMB), supports research centre at Bath University
British Board of Agrement Private linked to BRE Will certify renewable materials through an expensive process
NHBC Provides warranties for house building
Their guidance on natural materials in2011 is limited (NHBC 2011)
NHBC Foundation Private trust linked to BRE, provides research funding
Little evidence of interest in renew-able materials and has not supported any research (NHBC Foundation 2012)
LABC Local authority building control association
Has shown some interest in renewable materials
LABC warranty Private insurance company Has provided warranties for natural and renewable materials
British Standards Institute (BSI) Quango Little evidence of interest in renew-able materials
Construction Industry Research and Information Association (CIRIA)
Private trust Little evidence of interest in renew-able materials
Construction Products Association
Private association Has shown some interest in renewable materials