Does size matter: a comparison of methods to appraise thermal efficiency of a small house
Authors: Wallis, Louise; Dewsbury, Mark
he Energy Efficiency provisions, within the Building Code of Australia, have created many new challenges for architects and building designers. Prior to these provisions, general environmental design principles and ‘rules of thumb’ were used to design environmentally conscious dwellings. As the greenhouse agenda has advanced, the architect and building designer are now faced with understanding the effects of their original environmental design training, set parameters in the deemed to satisfy provisions of the BCA and house energy rating simulations. In some situations the logic of the rule of thumb approach seems to be questioned or contradictory to the resultant star rating. This paper will illustrate a recent design experience of a small residence in Launceston, Tasmania. The new dwelling was designed by using ‘rules of thumb’ for passive solar and environmental design and the philosophy of making a well insulated small box. The design was submitted to a Home Energy Rating assessor for certification. The dwelling initially failed to meet minimum requirement of 4 Stars (AccuRate) to the shock of the designers. This experience caused a self-reflection by the designers of their environmental knowledge and training. This resulted in a questioning of the methods of application of the thermal performance requirements in the BCA. Do the current deemed to satisfy provisions or simulation approaches used by building certifiers encourage or exclude perceived advantageous solutions? Are these approaches being put in place for large housing and unfairly effecting smaller housing? This case study approach will compare the results of each of these three approaches to design of the above mentioned small dwelling and a typical brick veneer project homes. As educators and researchers of environmental design within a school of architecture, this experience has been significant and had an immediate effect on curriculum and research.