Suggestion for new approach to overheating diagnostics

Abstract

In a changing climate there is increasing concern about the risk of overheating in UK buildings, particularly those with a low-carbon footprint which cannot rely on mechanical cooling. This gives rise to concern among building professionals about how overheating risk can best be assessed. Current Chartered Institution of Building Services Engineers (CIBSE) guidance uses a simple definition of overheating as the exceedance of 28C for more than 1% of occupied hours, based on simulations using weather files from a 'design summer year' (DSY). There is increasing evidence that this criterion is both insensitive and open to abuse. This paper uses field surveys of thermal (dis)comfort and the adaptive thinking behind the British and European Standard BS EN15251 to propose a new approach. It takes account of the effect of indoor and outdoor climate on the dissatisfaction of building occupants. An alternative definition of overheating in buildings is proposed, along with an approach to predicting the magnitude and/or frequency of occurrence of overheating in buildings.