Post-construction thermal testing: some recent measurements

In the UK, it has become apparent in recent years that there is often a discrepancy between the steady-state predicted and the measured in situ thermal performance of the building fabric, with the measured in situ performance being greater than that predicted. This discrepancy or gap in the thermal performance of the building fabric is commonly referred to as the building fabric ‘performance gap’. This paper presents the results and key messages obtained from undertaking a whole-building heat loss test (a coheating test) on seven new-build dwellings as part of the Technology Strategy Board’s Building Performance Evaluation Programme. While the total number of dwellings involved in the work reported here is small, the results illustrate that a wide range of discrepancies in thermal performance was measured for the tested dwellings. Despite this, the results also indicate that it is possible to construct dwellings where the building fabric performs thermally more or less as predicted, thus effectively bridging the traditional building fabric performance gap that exists in mainstream housing in the UK.