Insulation, orientation for solar access, window size, placement and shading, draught reduction, and the heat-storage capacity of floors and walls have long been accepted as important elements of energy efficient design in Australian residential buildings. As Australia prepares to meet its commitments to greenhouse gas reduction, ways of promoting the incorporation of these principles in new home construction are being explored. One option being considered is the addition of mandatory energy rating standards, such as the Nationwide House Energy Rating Scheme (NatHERS), to the Building Code of Australia.