This year Grosvenor commissioned five ‘smart’ historic retrofit projects in London designed to achieve the EnerPHit standard, the world’s leading sustainability standard for refurbishment that employs passive house principles. All five buildings are typical London terraces with attractive brick frontage and traditional single glazed windows. The building designer had to ensure that the criteria are achieved using various data analysis tools, such as PassivHaus Planning Package (PHPP) energy modelling tool, WUFI transient hydrothermal behaviour software that calculated realistic moisture deposit levels from internal condensation and London precipitation patterns, and THERM software used to complete 32 detail cold bridging calculations that evaluated the heat flow through various construction junctions. The key consideration on this project was not only to improve the current building energy efficiency but also to learn about both the process and the outcome of various measures. A number of monitoring devices were installed in the building to measure temperature, relative humidity and carbon dioxide levels that test the ‘guaranteed’ comfort levels and energy efficiency of the building and moisture meters collecting the water build up measurements inside the building fabric, which forms part of a wider study aimed to outline the risks of internal insulation in historic fabric. These should ensure that Grosvenor uses smarter specifications in all future refurbishment projects.