The Society for the Protection of Ancient Buildings (SPAB), the UK’s oldest conservation body, has been conducting research for the last three years into the energy efficiency of old buildings.
The society’s initial findings, to be officially released in October, and their ongoing investigations could have a significant impact on the way the energy performance of old and traditionally constructed buildings is approached.
Surprisingly, 73 per cent of the traditionally-built walls sampled – including walls of timber, cob, limestone, slate and granite – performed better than commonly supposed.
The SPAB report suggests that conventional industry practices were struggling to accurately represent the thermal performance of traditionally built walls. They compared the in-situ U-values, which describe the rate of heat transmittance or loss through walls, roofs, floors and the like, of various traditional vernacular walls against the theoretical U-value for these traditional walls.
The theoretical value obtained from the U-value calculations is used by professionals as the base-line for assessing thermal performance of different types of constructions. Even taking into account a possible error margin of up to 10 per cent, SPAB’s findings showed that old buildings were not as energy inefficient as the building industry has generally believed them to be.
The industry’s misconceptions about the energy efficiency of older buildings could have negative consequences for historic buildings as calculated theoretical U-values – suggesting poorer performance – could 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 and to the well-being of its inhabitants.
October, 2012 is likely to see the launch of the UK Government’s Green Deal, an initiative intended to reduce carbon emissions by revolutionising the energy efficiency of British properties. The research is being released to coincide with this and look at what some of the implications of the Green Deal might be for old and traditionally built properties.
“It’s all about understanding the building – how it works, how we use it and how we live in it. U-values are not the complete story,” said Jonathan Garlick, SPAB technical officer and project leader. “Energy efficiency is also about our behaviour in a building, moisture content in the structure, humidity, temperature, air-tightness, the quality of the air we breathe. These are all issues that we have been looking at in further stages of the project.”
Until recently The SPAB’s research work has been self-funded, but with the importance of the project and the information it is generating, they are now receiving financial support under English Heritage’s National Heritage Protection Commission Programme.
“The work of the SPAB has been very valuable by demonstrating that old buildings are inherently more energy efficient than is generally assumed,” said Chris Wood, English Heritage’s head of building conservation and research. “Together with the research that English Heritage is conducting, there is now a steadily growing body of compelling evidence that shows the current method industry method of assessing the energy performance of historic buildings is not accurate. The conclusions of this work suggest that more will be gained by carrying out sensitive interventions, rather than the drastic solutions that are being heavily promoted.”