An exploration of the selection of design summer years to define the overheating risk of buildings

Abstract

Building engineers are faced with a difficult problem: how to design habitable spaces that conform to planning constraints, building regulations and low levels of energy use, whilst at the same time making them comfortable for us to live in. Thermal comfort assessments are an essential part of the design process in building construction, which in the UK involves using summer weather reference data called design summer years (DSYs) in building simulation models. Recent work has reformulated the DSYs based on probable return periods of overheating events to better describe their relative severity. However these events are still based on external temperatures alone and may not translate to the full risk to occupants. The work presented here considers how warmth metrics used to choose probabilistic design summer years can be extended to include weather variables such as solar radiation and relative humidity. It is found that the relative ranking of the warmest years and thus the selected overheating year depends on the metric used. The choice of which, has consequences for the assessment of overheating due to the underlying weather patterns within the selected year and could impact on building design.