Looking Critically at Heat Loss through Party Walls

Heat loss through party walls to outside (not the neighbouring dwelling) has received considerable attention in the UK, and this was flagged as a serious omission from the UK Building Regulations in 2010-12. There was evidence of significant heat loss between adjoined terraced or semi-detached new homes, which was increasingly important as heat loss from other parts of dwellings was being reduced. As a result, Building Regulations were changed so that other parts of the building envelope had to be improved in new homes to compensate for heat loss through the party wall. However, this empirical work based on measuring heat loss through the party walls of 55 UK dwellings indicates that fears about high heat loss through party walls may have been exaggerated. While a minority of dwellings (less than 10%) do suffer from a “thermal bypass” through the party wall, for the vast majority of existing homes with party walls, heat loss through the party wall is minimal. There may be a case for revising UK Building Regulations to reflect this new evidence, and for re-directing the efforts aimed at reducing heat loss through party walls towards other opportunities to improve the energy efficiency of dwellings.