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.

    (RAE 2010)

    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.

    (ARC-PEACE 2012)

    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

  • Holistic d



    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.

    Holistic design

    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


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