The rating of buildings using thermal models represents a contrasting regulatory approach to prescriptive measures to improve the energy efficiency of buildings. This paper investigates the relationship between measured household energy use for thermal comfort purposes and the modelled thermal energy calculated under the Nationwide House Energy Rating Scheme (NatHERS), which is used for the regulation of minimum energy performance standards for new housing in Australia. Two different sets of housing in Adelaide, South Australia which were built a decade apart and to significantly different energy performance standards represent the basis of this study. The results show that better insulated houses represented by higher stars under the NatHERS scheme do use less energy for heating and cooling.