The aim of this research is to garner a full understanding of low energy construction across a variety of sectors in countries throughout the world, and then investigate how the Passiv Haus concept was applied to a Supermarket in Ireland. In order to carry out this investigation, a case study was performed on the energy efficiency and performance of a Tesco store in Tramore. It was found that its electrical cosumption was 24% lower than equivalent stores which were not built to the high specification of the Passiv Haus Standard. As this supermarket is the first of its kind in the world, and with both the SEAl and the European Parliament pushing for this method of construction to be adopted, this standard will most likely in some shape or form become a new building standard in Ireland. This supermarket offers a unique insight into what can be expected in building design and construction in this sector if it is undertaken.