The practice was commissioned by the owners of Little Keynes to design a new environmentally conscious four-bedroomed house on a plot of land measuring approximately 1.5 acres adjacent to the main residence. From the start it was clear that the overriding aim was to create a low-energy, low-cost and, most importantly, comfortable home for our clients to enjoy throughout their retirement. The Passivhaus standard was the clear choice. Working closely with our client and the design team we were able to arrive at a scheme that not only suited our client’s lifestyle and addressed the particular nature of the site but also adhered to, and in fact surpassed, the rigorous requirements of the Passivhaus standard. Contrary to popular belief, construction costs for Passiv design is comparable with other construction forms, any additional capital costs are soon recovered through reduced running costs. The client’s needs for optimum comfort levels together with sustainable design made the Passivhaus standard an obvious choice.