{"id":519,"date":"2017-06-15T12:16:05","date_gmt":"2017-06-15T12:16:05","guid":{"rendered":"http:\/\/blogs.sps.ed.ac.uk\/global-environment-society-academy\/?p=519"},"modified":"2017-06-14T18:11:41","modified_gmt":"2017-06-14T18:11:41","slug":"why-renewables-can-improve-the-quality-of-our-home-life","status":"publish","type":"post","link":"https:\/\/blogs.sps.ed.ac.uk\/global-environment-society-academy\/2017\/06\/15\/why-renewables-can-improve-the-quality-of-our-home-life\/","title":{"rendered":"Why renewables can improve the quality of our home life"},"content":{"rendered":"

By Mr. John Brennan<\/a>; Architecture & Landscape Architecture, Edinburgh College of Art<\/p>\n

Introduction by <\/em>Dr Faye Wade<\/em><\/a>, Science, Technology and Innovation Studies, University of Edinburgh <\/em><\/p>\n

With 74% of Scotland\u2019s household energy use occurring through space heating, and another 13% through water heating, the built environment has to be part of any strategy for a more sustainable future. Indeed, the Scottish Government\u2019s Energy Strategy seeks to make Scotland\u2019s buildings near zero carbon by 2050, delivering this through Scotland\u2019s Energy Efficiency Programme (SEEP), which includes funding for the retrofitting of existing homes, and seeks to increase the adoption of low carbon heating solutions. However, in order to achieve the Energy Strategy\u2019s ambitious target to achieve a \u2018low carbon transformation\u2019 in the built environment by 2050, it is important to think about the realities of delivering low carbon buildings. John Brennan, Programme Director for an MSc in Advanced Sustainable Design, considers some of the challenges:<\/em><\/p>\n

Over the years,\u00a0we\u2019ve witnessed a transformation in the regulation of energy consumption in the housing market.\u00a0In this period I designed and delivered\u00a0a series of low carbon homes and now reflect that we must be careful what we wish for.\u00a0\u00a0Governments have an obligation to deliver on agreed national and transnational targets and in\u00a0Scotland a\u00a0vehicle for this has been the\u00a0various iterations of The Sullivan Report. In\u00a0its current guise its ambition is\u00a0to enforce \u2019nearly zero new buildings\u2019 by 2019.<\/p>\n

A significant influence is the Passivhaus Institut. Independent of any\u00a0government, it advocates a relentless focus on heat loss\u00a0until predicted energy loads\u00a0are negligible. This is achieved through compact shape, orientation for passive heat gain, superinsulation, and near total air tightness harnessed to\u00a0mechanical ventilation and heat recovery. Metabolic gains from occupants, incidental gains from the equipment they use and heat collected from solar gain through windows should be enough to keep the house comfortable even in winter. Intentionally, there is no obligation to employ renewables.\u00a0What is attractive to regulators is a design method defined as a series of quantitative thresholds. A passive house is only a passive house when it achieves a verifiable dwelling air change rate of 0.6\/hr@50pa and a projected heating load of 15kWh\/m2<\/sup>\/year<\/p>\n

In theory, this seems inherently virtuous but in practice can deliver new housing stock in danger of being neither energy efficient nor fully fit for habitation. The nub of the problem lies in the nature of the construction industry. Achieving a quantitative standard requires careful design and obsessive quality control. This is possible in\u00a0bespoke operations or sophisticated manufacturing techniques but neither of these traits\u00a0are characteristics familiar to\u00a0the UK construction industry. To achieve air tightness approaching passive house standards requires a level of fit otherwise reserved for the car industry.\u00a0[fig.1] Passive house is an achievable but inherently fragile standard.<\/p>\n

As of now, the national baseline for air tightness\u00a0is around 5 times less onerous than the passive house standard, but past experience suggests a progressive uplift over time to deliver the promises of Sullivan. Over forty years, insulation standards have increased five-fold with little in the way of adverse effects for the householder. Seeking to replicate this process for air tightness will be more troublesome.\u00a0\u00a0Increasing air tightness can degrade air quality in our homes. Recent research shows that current standards for air tightness without effective mechanical ventilation either put occupants\u2019 health at risk or make a mockery of energy conservation in the heating season through intermittent episodes of uncontrolled exfiltration (otherwise known as opening windows) [2]. However as passive house has gifted the means to define\u00a0clear air tightness targets to our regulators, the likelihood is that the baseline standard will become progressively more onerous.<\/p>\n

The nub is that environmental regulation in building must be based on quantitative standards given the sheer volume of individual projects\u00a0that require oversight and approval. Governments therefore\u00a0only manage what can be measured;\u00a0an approach that tends the certainties of measurement methodologies as found in Passive House. However, the realities of housing design are\u00a0more complex. It can be\u00a0explained by Dean Hawkes who identified two fundamental strands in environmental design, those of exclusive and selective environments.\u00a0 \u00a0[fig.2]<\/p>\n

Exclusive Mode <\/strong>buildings operate through\u00a0separation of internal and external environmental conditions and regulation of thermal comfort is through mechanical means. Except in relation to collecting solar gain, Passive Houses are Exclusive Mode buildings.<\/p>\n

Selective Mode <\/strong>buildings embraces surrounding\u00a0climatic and environmental contexts. They maximise solar gain and encourage unassisted\u00a0ventilation flow. \u00a0They have much more freedom in shape and form, and are not compelled\u00a0to seek out the most efficient way to enclose a particular volume. They remain low energy buildings but recognise\u00a0that depending on time, season and location, some form of heat is required to maintain comfort in the home. The selective mode approach to building services are that\u00a0\u2018mechanical systems for heating, cooling and ventilation and lighting should be regarded as supplementary to the primary control provided by the selective built form\u2019. [2]<\/p>\n

On the face of it,\u00a0housing\u00a0standards that reduce heating demand\u00a0to a negligible level are praiseworthy. However, it comes with a susceptibility\u00a0to poor air quality and dependency on mechanical plant, all of which delivered by industry with an entrenched inability to deliver decent levels of\u00a0fit and finish. Selective Mode building accepts that from time to time, heating and cooling is required to maintain comfort. In this context, the question is then to consider those forms of generation that are most benign in their impact.<\/p>\n

I would suggest it is inadvisable\u00a0for building regulation to focus on ever higher standards of\u00a0air tightness as a means to progressively reduce heating demand in our homes.\u00a0To use a medical analogy, such medication can be accompanied by\u00a0unpleasant side effects. Our legislators should continue to recognise that renewable energy only plays a part in reducing our carbon footprint, but also is more likely to keep our households healthy.<\/p>\n

We don\u2019t usually value our homes in terms of their\u00a0measurable performance. Some of us enjoy the comfort, control and running costs that come with a finely calibrated passive house which embodies the best of the exclusive tradition in environmental design. Many others wish to have homes that have greater freedom in their design, a closer relationship to external worlds\u00a0and the ability to stand up to robust treatment by the householder. These are the key characteristics of the selective tradition and ideally, both selective and exclusive modes\u00a0should be accommodated for by our regulators. \u00a0It may seem counter intuitive, but\u00a0now I\u00a0tend not to\u00a0define the benefits of renewable energy technologies in terms of resource use and carbon impact. Instead, we should advocate their use to\u00a0enable healthy, forgiving and long-lasting homes that help us all\u00a0along the way to having the\u00a0freedom to live as each of us wish.<\/p>\n

[1]\u00a0Howieson, S.G., Sharpe, T. & Farren, P., 2014. Building tight \u2013 ventilating right? How are new air tightness standards affecting indoor air quality in dwellings?<\/u> Building Services Engineering Research & Technology, 35(5), pp.475\u2013487.<\/p>\n

[2]\u00a0Hawkes, D., McDonald, J. & Steemers, K., 2002. The Selective Environment<\/u>, London: Spon Press.<\/p>\n

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Fig 1<\/p>\n

Passive House Construction<\/p>\n

These photographs of a passive house designed and built by our practice shows the disconnect between the domestic interior and the materials, technology and precision required to reach required levels of air tightness.\u00a0 [photographs Julie Wilson]<\/p>\n

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Fig 2<\/p>\n

Exclusive and Selective Mode Design<\/p>\n

Both are entirely valid approaches to designing sustainable homes. The illustration shows a cross section through a house identical in its rooms and shape. The top illustration shows how Exclusive Mode buildings are fully sealed and rely on mechanical ventilation. Below this, we see how Selective Mode buildings have a more porous relationship to the outside often using buffer spaces to collect heat and mediate temperature. [illustration John Brennan]<\/p>\n

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By Mr. John Brennan; Architecture & Landscape Architecture, Edinburgh College of Art Introduction by Dr Faye Wade, Science, Technology and Innovation Studies, University of Edinburgh With 74% of Scotland\u2019s household energy use occurring through space heating, and another 13% through … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":114,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[211],"tags":[],"acf":[],"_links":{"self":[{"href":"https:\/\/blogs.sps.ed.ac.uk\/global-environment-society-academy\/wp-json\/wp\/v2\/posts\/519"}],"collection":[{"href":"https:\/\/blogs.sps.ed.ac.uk\/global-environment-society-academy\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.sps.ed.ac.uk\/global-environment-society-academy\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.sps.ed.ac.uk\/global-environment-society-academy\/wp-json\/wp\/v2\/users\/114"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.sps.ed.ac.uk\/global-environment-society-academy\/wp-json\/wp\/v2\/comments?post=519"}],"version-history":[{"count":5,"href":"https:\/\/blogs.sps.ed.ac.uk\/global-environment-society-academy\/wp-json\/wp\/v2\/posts\/519\/revisions"}],"predecessor-version":[{"id":535,"href":"https:\/\/blogs.sps.ed.ac.uk\/global-environment-society-academy\/wp-json\/wp\/v2\/posts\/519\/revisions\/535"}],"wp:attachment":[{"href":"https:\/\/blogs.sps.ed.ac.uk\/global-environment-society-academy\/wp-json\/wp\/v2\/media?parent=519"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.sps.ed.ac.uk\/global-environment-society-academy\/wp-json\/wp\/v2\/categories?post=519"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.sps.ed.ac.uk\/global-environment-society-academy\/wp-json\/wp\/v2\/tags?post=519"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}