Modelling study of the impact of thermal comfort criteria on housing energy use in Australia

It is an increasing challenge for building designers in the 21st century to provide for thermal comfort at minimum energy cost by taking into consideration both the current and the future warming climate. Most previous studies have focused on thermal comfort in non-residential buildings under current climatic conditions. This study evaluates the impact of thermal comfort criteria by lowering the acceptability limits on space cooling energy requirements for Australian residential buildings, under both the current and projected future climates (with an assumed global warming of 2 °C) through building simulations using three different types of typical building constructions - lightweight, heavyweight, and a combination. The results show that under both current and future climates, relaxing thermal comfort criteria by lowering the acceptability limits from 90% to 70%, has a small or minor impact on space cooling energy consumption for the heavyweight and combination type construction in the subtropics (Brisbane), warm temperate (Sydney), temperate (Melbourne) and cool temperate (Hobart) climate regions. However, it has significant impact on space cooling energy consumption (saving more than 40%) in tropical regions (e.g. Darwin) and regions with a hot summer climate (e.g. Alice Springs and Mildura). For the lightweight type construction under the current climate, relaxing the acceptability limits will increase the energy star rating by 3.6 stars in Darwin, 0.5 star in Mildura, 0.3 star in Alice Springs and 0.2 star in Brisbane. Under the projected future climate, relaxing the acceptability limits to 70% will increase the energy star rating by 1.6 stars in Darwin, 1.2 stars in Brisbane, 0.7 star in Alice Springs and 0.3 star in Mildura. It was also found that for all the climates, relaxing the acceptability limits from 90% to 80% has greater impact than that from 80% to 70%. By relaxing the acceptability limits, the space cooling energy consumption can be minimized in tropical and subtropical regions for high set lightweight houses.