In their interim progress report, Closing the gap between design and as-built 25 performance they say: ‘There is a general lack of understanding across developers, designers and planners 26 about the potential impact they can have on energy performance and buildability.’’ 23 Performance Gap | Zero Carbon Hub 24 EPCs as Efficiency Targets 25 Closing the Gap between Design & As-Built Performance (zerocarbonhub.org) 26 https://www.zerocarbonhub.org/sites/default/files/resources/reports/Closing_the_Gap_Between_Des ign_and_As-Built_Performance-Evidence_Review_Report_0.pdf 25 The report goes on to highlight concerns including: lack of a robust energy performance tool; the need for products to be tested for energy performance as systems of fabric rather than individual components; problems associated with adoption of improvised approaches being used on site without understanding of energy performance implications; requirement for a review of thermal bridge calculations; and that knowledge, skills and working practices within the industry are a serious concern and will have an influence on both the performance gap and the ability to close it.