Preparing traditional buildings for climate change

Introduction

The heritage sector needs to contend with risks arising both directly from climate change, and from perceptions of old buildings as obstacles to climate change adaptation. This briefing gives pointers for dealing with both of these challenges, introduces the work of some of the key organisations involved, and highlights key sources of further information.

Most heritage sector publications suggest that the buildings of traditional construction form up to 25 per cent of the UK’s building stock, but this could be up to 35 per cent according to a Building Research Establishment (BRE) literature review (Solid wall heat losses and the potential for energy saving) published by the Department of Energy and Climate Change (DECC) in 2015. In either case, the role of these buildings in climate change is clearly substantial and is arguably the single most important issue faced by the conservation sector.

Extreme weather events

The 2018 Intergovernmental Panel on Climate Change (IPCC) Special Report highlights that an increased risk of extreme weather events will occur with increasing frequency, including heavy rainfall and flooding. For traditional buildings, this could have a particularly high impact, bringing rainwater disposal systems and the capacity of traditional materials to cope with such extreme conditions under serious pressure, and putting buildings that are already in poor condition or under repair at high risk. The immediate challenge is how to cater for increasingly severe weather events with the security of traditional buildings in mind. Good building maintenance is vital. Measures such as increasing the size of rainwater goods can be considered, but these often occur at the expense of the building’s original character and fabric, which may not deal well with driving rain. Historic England’s ‘Flooding and Historic Buildings’ gives guidance on how to manage flood risks and improve resilience in relation to historic buildings, and on dealing with the consequences if the worst should happen. Any measures taken should be appropriate to the building’s character and performance.

Strategic mitigation challenges

The IPCC Special Report calls for radical change to help mitigate the effects of climate change within 12 years, bringing even greater urgency to existing government retrofit strategies. The government’s Clean Growth Strategy (2017) wants all fuel-poor homes, as many privately-rented homes, and as much social housing as possible to reach Energy Performance Certificate (EPC) band C by 2030, with as many homes as possible to achieve this target by 2035 ‘where practical, cost-effective, and affordable’. Such practicalities are, however, conspicuously absent from the Committee on Climate Change’s independent assessment, which notes that 19 million UK homes out of 27 million (70%) are currently below band C. Reading between the lines, the implementation of these targets (coupled with the current disregard for heritage significance) could amount to the single biggest threat to historic and traditional buildings and areas. The government overlooks the need to put buildings into good repair before installing retrofit measures, and government-promoted retrofit schemes have taken a one size fits all approach, assuming that what will work for buildings of modern construction will also work for traditional buildings.

These challenges overlie a longstanding crisis in training for the conservation and repair of traditional construction. The 2013 Skills Needs Analysis of repair maintenance and retrofit published by English Heritage, Historic Scotland and the CITB noted that 89 per cent of contractors working in this sector were general construction companies, and 87 per cent did not have formal qualifications relating to working on traditional buildings. These deficiencies, multiplied at scale as retrofit targets bite, are detrimental because, as previously mentioned, putting buildings into good repair is a vital precursor to any retrofit measure, and retrofit measures applied without understanding of traditional construction can exacerbate existing problems and create new ones. Anyone familiar with the effects of cement mistakenly applied to breathable buildings can foresee the consequences of applying impermeable insulation to a traditional building – not only is there a risk of damp and decay, but saturated walls lead to increased heat loss.

The heritage sector’s response and the STBA

Problems associated with solid wall insulation and other issues arising from the government’s Green Deal were raised by the Society for the Protection of Ancient Buildings (SPAB) in a letter to The Times in late 2011. This was soon followed by a COTAC conference in November 2011, ‘Improving the Thermal Performance of Traditional Buildings’, from which the presentations are still scarily relevant. Research by the heritage sector (SPAB, Historic England and Historic Environment Scotland) albeit from very small samples of buildings, cast doubts on the government’s approach. The Sustainable Traditional Building Alliance (STBA), brought together sustainability, heritage and mainstream industry interests, under the aegis of the Sustainable Development Foundation, with the National Trust, Historic England, and SPAB as patrons. It challenges industry thinking in relation to traditional buildings and moisture performance. STBA’s research on the poorly understood but vital issue of moisture in buildings is published by the British Standards Institute (BSI) as a white paper.

Risks and unintended consequences

STBA’s 2012 ‘Planning Responsible Retrofit of Traditional Buildings’ report prompted DECC to commission a BRE study of solid wall buildings. Its key output was the solid wall literature review mentioned above, which highlights risks and unintended consequences when applying inappropriate measures to heritage buildings. The BRE’s evidence on unintended consequences remains unpublished, but key issues were highlighted by Colin King at Ecobuild 2014, and in the academic study ‘100 Unintended Consequences of Policies to Improve the Energy Efficiency of the Housing Stock’ by Clive Shrubsole, Alexandra Macmillan, Mike Davies and Neil May, in the April 2014, special issue of ‘Indoor and Built Environment’. The most devastating published evidence has been published only recently in a ‘Passive House Plus’ article, in relation to solid wall insulation failures in 300 dwellings at Fishwyck, Preston. To date, there remain no safeguards for traditional buildings within Energy Company Obligation (ECO) or other government-promoted schemes.

Whole-life cycle and the circular economy

Government initiatives for energy conservation and carbon reduction in existing buildings have focused on performance in use, not embodied energy and whole-life cycles. They have disregarded the energy and carbon costs of construction, of manufacture and installation of energy-saving measures, and of demolition or disposal. No consideration has been given to the carbon and financial costs of rectifying inappropriate measures. Consideration on a whole-life basis, would put traditional buildings in a far more favourable light. The increasing focus on reducing waste and the circular economy offers some hope for rectifying this.

Standards and guidance

For appropriate guidance on working with traditional buildings, it is useful to start with the building regulations Part L1B and 2B special consideration for ‘buildings of traditional construction with permeable fabric that both absorbs and readily allows the evaporation of moisture’. British standard BS 7913:2013 guide to the conservation of historic buildings is the key document in terms of overall sustainability and energy efficiency. Two useful BS-published European standards include the little-known sustainable construction standard, BS EN 15978:2011, which supports whole-life consideration, and BS 16883:2017 conservation of cultural heritage – guidelines for improving the energy performance of historic buildings. Chapter three of the government’s guidance to landlords and local authorities on the domestic private rented property minimum standard recognises differences in moisture performance between modern and historic buildings; it promotes a whole-house approach (see also STBA’s What is Whole House Retrofit?). The forthcoming Publicly Available Specification (PAS) 2035 will apply to all publicly funded retrofits including ECO3. It will cover vital but so far overlooked aspects of the process: survey and design, and consideration of the interactions between measures.

Advice

Historic England and Historic Environment Scotland provide technical advice on energy conservation and retrofits.

For user-friendly overviews, see SPAB’s briefing ‘Energy Efficiency in Old Buildings’ and STBA’s ‘Planning Responsible Retrofit’. The latter balances energy and environmental considerations, healthy buildings and occupants, and heritage. It promotes the whole building approach integrating fabric measures, services, and how people live in and use the building. It goes on to consider retrofit challenges, problems with standards and regulations, and risks.

For moisture in buildings, see also SPAB’s ‘Control of Dampness’.

STBA’s interactive guidance wheel enables consideration of potential retrofit measures, singly or in combination, for specific buildings and contexts. Potential advantages and concerns are highlighted in relation to technical, heritage, and energy considerations. For a more comprehensive guide, including good practice details, see ‘A Bristolian’s Guide to Solid Wall Insulation’ produced by STBA for Bristol City Council and DECC. This covers the whole range of responsible retrofit, with potential for replication (adjusted to local conditions) across the whole country. For evolving best practice and practical solutions in the non-domestic and charitable sectors, try the Fit for the Future network.

Awareness, skills and training

Delivery of government retrofit targets through PAS 2035 will depend on having a workforce that understands traditional buildings and can specify and carry out appropriate repairs and retrofit. The new PAS 2035 role of retrofit coordinator as developed by the Retrofit Academy does not require understanding of traditional buildings and their significance for either repairs or retrofit (despite the requirements of BS 7913:2013). It is not clear whether retrofit coordinators dealing with traditional buildings will also need to have the Level 3 Award in ‘Energy Efficiency Measures for Older and Traditional Buildings’, the qualification specifically developed to meet this need. The question is, will this change in the published PAS 2035?

Courses to train appropriately skilled professionals are in short supply. IHBC members should have a head start if adding retrofit skills to their existing competences. Courses such as the Environment Study Centre’s ‘Energy Efficiency Measures for Older and Traditional Buildings’ and the Green Register’s ‘Retrofitting Traditional Buildings – Policy and Practice’ are very good starting points. The diploma in Domestic Retrofit Coordination should also be considered, but it may be worth waiting until the dust has settled after PAS 2035 is published.

This article originally appeared as ‘Preparing for climate change’ in IHBC’s Yearbook 2019, published by The Institute of Historic Building Conservation in 2019. It was written by John Preston, STBA’s heritage chair and IHBC’s Green Panel convenor.

--Institute of Historic Building Conservation

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