Neutral, comfort or preferred: what is a relevant model for acceptable thermal environmental conditions for low energy dwellings in Australia?

Abstract

Thermal performance assessment is an important means in understanding the future performances of a building design. Existing assessment methods employed to demonstrate compliance with minimum Energy Efficiency performance requirements for residential buildings in Australia use static thermostat settings to determine heating and/or cooling loads by which performance in judged. This approach has been shown to be inappropriate in cases where the dwelling is designed to use little or heating or cooling during actual operation. The research in the paper suggests that, in the assessment of these types of ‘low energy’ house designs, the use of comfort criteria would be a more appropriate measure of performance. Over 6000 thermal comfort vote surveys were collected from a longitudinal thermal comfort study of 40 Australian households comprising of 20 earth buildings in Melbourne, Victoria and 20 naturally ventilated dwellings in Darwin, the Northern Territory. The results demonstrate that existing models of thermal comfort do not adequately encompass the extent of conditions that these occupants find acceptable. Based on the collected data, this paper offers a model of thermal preference that can be used in the performance assessment of the two types of dwellings studies. Such an approach would assist in recognising the diversity of comfort related expectations, behaviours and preferences that contribute to the thermal performance of low energy dwellings.