Improved energy efficiency in new residential buildings is typically being sought across the developed world through changing requirements in building and/or planning regulations. Stringency is set to further increase significantly in attempts to meet climate change mitigation goals. However, new regulation is usually met with reticence from sectors of the building industry, one reason being the additional costs implied in meeting higher performance standards for more energy efficient buildings. One low cost option, investigated in this paper, is to orient buildings in order to maximise their passive solar benefits. Using a range of 81 different detached dwelling designs, a modelling experiment was conducted in order to assess the implications of orientation on modelled thermal energy efficiency. Design adaptability to orientation change was modelled across two scenarios; current building energy efficiency standards and pending improved energy efficiency standards. The effect of size and overall energy efficiency rating was included in consideration of variance across orientations. Results show that higher standards are easier to apply to smaller dwellings, and costs are lower. Also, higher performing designs are more flexible across different orientations, producing lower standard deviations of mean ratings. The findings indicate that passive solar design is a concept that can readily be incorporated into house plans at the design stage. Recommendations for further empirical research are also made. (c) 2010 Elsevier Ltd. All rights reserved.