Airtightness and Thermographic Study of 20 Dwellings for Wakefield & District Housing

Wakefield & District Housing (WDH) commissioned the Leeds Sustainability Institute (LSI) at Leeds Beckett University to undertake pressurisation tests and thermographic surveys on 20 semi-detached dwellings (of which only 19 granted researchers access), these were;  14 British Iron Steel Federation (BISF) homes with external wall insulation (EWI)  1 BISF without EWI  2 solid brick properties with EWI  2 solid brick properties without EWI The aim was to identify the influence of EWI on the air tightness of the buildings. The results showed that there was no noticeable improvement in the airtightness of dwellings that had EWI compared to those without EWI in either BISF or solid‐walled dwellings. A larger sample size of BISF homes without EWI and both solid‐walled properties with and without EWI would be needed to assess if this finding was statistically significant. CO2 decay analysis was used in an attempt to validate the blower door results however the results were inconclusive due to a low sample size and an uncontrolled conditions due to occupant activity. Improving airtightness is not the main function of EWI and this has been sustained by our findings. The results confirm that the fabric performance benefit of EWI is restricted almost exclusively to improving wall U‐values, i.e. reducing heat loss through the fabric, not affecting heat loss through uncontrolled ventilation in the dwellings.