Voices from across the built heritage and conservation sector expressed concern in August at the lack of representation for old buildings within the terms of the Green Deal - the official drive to improve the energy performance of the nation’s buildings set to be launched next year.

The Society for the Protection of Ancient Buildings (SPAB), supported by Kevin McCloud, The National Trust, Church of England, and many other organisations and individuals, sent letters to The Rt Hon Chris Huhne MP, Secretary of State Department for Energy and Climate Change and to The Times calling for the needs of older buildings to be represented in research and planning activity around the proposals. So far the emphasis has largely been on measures suitable for modern construction.

Signatories* warned that the drive to promote the complete thermal upgrading of pre 1919 buildings could be storing up expensive future problems for both building fabric and human health. Inappropriate forms of insulation and the sealing up of interiors take little account of the fact that these buildings, which number millions, perform differently from modern ones and need to ‘breathe’. They are likely to require a different approach, in particular with regard to the movement of moisture within them.

The letter concluded: “While we strongly support the aim of reducing carbon emissions from the nation’s building stock, we call on the Government to involve bodies knowledgeable about old buildings in research and planning for The Green Deal. Many of these bodies already have helpful research to contribute but to date have not been called on to do so.”

SPAB is currently conducting and collating research into the energy efficiency performance of a range of older properties built using traditional materials. Results to date suggest that these buildings actually perform better than expected.

The study suggests that conventional industry practices are struggling to represent accurately the thermal performance of traditionally built walls. Ultimately, this could have negative consequences for historic buildings as calculated theoretical U-values (suggesting a poorer performance) may lead owners and professionals to adopt disproportionate energy saving interventions that may not only be unnecessary, but also invasive and potentially harmful to the fabric of a building. Among measures likely to be promoted as part of the Green Deal is the insulation of walls internally and possibly externally, with the danger that commercial pressures may encourage the use of materials inappropriate for old buildings.

SPAB’s research so far suggests that 79% of the traditionally built walls sampled – including walls of timber, cob, limestone, slate, and granite – actually perform better than expected. Even taking into account a possible error margin of up to 10%, SPAB’s findings show that old buildings may not be as energy inefficient as the building industry has generally understood them to be. Much of the basic data which the industry currently uses is derived from studies of buildings in Germany.  The Society believes it is only by understanding our own old buildings fully that we can decide whether the insulation upgrades we are making are of any energy efficient or sustainable benefit.

SPAB Building Performance Survey
During 2009-10 winter season the SPAB undertook a programme of research into the U-values of traditionally built walls. This resulted in a number of alternative in situ U-values and cast doubt on conventional U-value calculation practices for traditional walls of certain constructions. (The findings of this research are detailed in the SPAB Research Report 1: U-value Report at http://www.spab.org.uk/advice/energy-efficiency/)  As a result of this research work it was acknowledged that heat loss as quantified by U-value assessment is only a part of a wider set of factors that affect the energy profiles of traditional buildings.

In order to engage more comprehensively with debates concerning energy efficiency and older buildings more wide-ranging forms of building performance assessment are required. The SPAB Building Performance Survey is an attempt to provide such an assessment by looking at a range of factors that may affect the energy performance and environmental behaviour of traditionally built dwellings.

The SPAB Building Performance Survey has been supported in part by a grant from the Dartmoor National Park Sustainable Development Fund. Seven different properties, four of which are located in and around the Dartmoor area, were identified as being of traditional construction and scheduled for various forms of energy improvement interventions over the coming year (2011-12).

During a two week period between January and April 2011, while still in an 'unimproved' condition, various aspects of the energy performance and environmental behaviour in these seven properties were monitored and recorded. It is expected, once refurbishment work has been completed, that these same buildings will once again be measured during the 2011-12 winter season. When complete this study will present an analysis of the various parameters relating to fabric performance and the environment both before and after refurbishment. It is hoped that this approach will enable an assessment of points of difference and change, beneficial or otherwise within the properties as a result of the energy 'improvement' work.

The SPAB Building Performance Survey looks specifically at:-

• fabric heat loss through the U-value measurement of wall elements both in the form of in situ and calculated U-values,

• air infiltration through air permeability testing and thermographic survey,

• Moisture, room and wall moisture including wall surface and interstitial moisture behaviour

• indoor air conditions and comfort levels via the measurement of CO2, interior temperature and relative humidity.

At the time of writing, this research project is in process, data from the first season’s ('unimproved') monitoring has been collated and subject to a preliminary analysis. An Interim Report providing details of the projects findings thus far will be published in time for our Technical Day on Old Building Energy Efficiency Research: The Latest Thinking & Results Update to be held at Shaw House, Newbury, Berkshire on 18th October 2011. For further information on this event please go to SPAB’s website www.spab.org.uk or speak to Skye Dillon, SPAB Course Organiser on: 020 7456 0915

A final report detailing all the research outcomes will be published after completion of the second monitoring cycle and is expected in the summer of 2012.

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