Changes in building design during the twentieth and twenty-first centuries have been largely focussed on driving safety and reducing capital expenditure, with less attention given to improvements in building energy efficiency. However, energy efficiency in buildings and the associated supply chain should be a vital consideration as almost half of the UK's carbon dioxide emissions are attributed to their construction and operation. Today, the city landscape is faced with a growing number of smart buildings that are designed to operate at an optimum performance level. However, the performance gap between the anticipated energy use and actual consumption is increasing. This paper explores the possible justifications for this and suggests that the gap can be primarily attributed to the interaction between design and user behaviour. Clues to how this performance gap problem can be reduced may come from traditional or vernacular design, where the design ethos evolved around the requirements of the user. This paper offers a brief appraisal of traditional construction methods and materials. Specific aspects of traditional design have been highlighted for recommended integration into contemporary design. This is a qualitative assessment which focusses on the UK case and recommendations for quantitative analysis, as part of potential further study, are also included.