Review on Overheating Evaluation Methods in National Building Codes in Western Europe

Due to the current rate of global warming, overheating in buildings is expected to become more intense and frequent. High indoor temperatures affect occupants' comfort, productivity, and health. In the last twenty years, the "time-integrated overheating evaluation methods" have been introduced in the standards to describe the extent of overheating over some time and prevent the uncomfortable phenomena. In this paper, we critically review those methods found in the national and regional building codes based on the Energy Performance of Building Directive (EPBD) in Belgium, France, Germany, the UK, and the Netherlands. The methods are analysed according to eight measures including, 1) dependency on comfort model, 2) dependency on comfort categories, 3) symmetric or asymmetric, 4) all hours or occupied hours, 5) normalization to occupied hours, 6) short-term or long-term criteria, 7) single-zone or multi-zone, and 8) comfort-based or heat balance-based. We found that the occupant adaptation is largely neglected in the reviewed building codes except for France. We also found that the building codes in Belgium (Wallonia and Flanders), Germany, the UK, and the Netherlands have only or at least one criterion based on the steady-state heat balance equations. The study outcomes also provide practical recommendations for policymakers to improve the regional and national overheating evaluation methods towards climate change-proof residential buildings.