Get Sust! Issue 27

Domestic insulation – energy savings and comfort levels

Why do domestic cavity wall and loft insulation consistently fail to deliver the energy savings predicted by calculation techniques such as BREDEM? Researchers at Glasgow Caledonian University have reviewed 13 studies on the relationship between predicted and the actual energy savings to find out.

The authors conclude that the discrepancy, known as a ‘reduction factor’ is caused in part by changed internal temperatures (the ‘comfort factor’), with the remainder due to other factors such as insulation performance, occupancy and ventilation.

Their report, ‘Review of Differences between Measured and Theoretical Energy Saving in Housing for Insulation Measures’ is published by Defra.

Their analysis of the 13 studies suggests that the reduction factor for houses where both measures had been installed could be 50%, of which comfort factor makes up 15% (although, of course, there will be  considerable variation between different houses in practice). They also studied the impact of both measures separately.

Learn more:

•

‘Review of differences between measured and theoretical  energy savings for insulation measures’ by Chris Sanders and Mark Phillipson, Centre for Research on Indoor Climate and Health, Glasgow Caledonian University, can be downloaded from www.defra.gov.uk/environment/energy/research/