<p>The Zero Carbon Hub has identified 15 issues which need urgent attention in order to close the so-called performance gap between the design and as-built energy performance of new homes.</p> <p>A report published on March 4 by the Hub called "Closing the gap between design and as-built performance" ranks issues in four categories - "Priority for Action", "Priority for Research", "Retain a Watching Brief" and "No Immediate Action".</p> <p>The 15 issues in "Priority for Action" include:</p> design teams not understanding site and buildability issues calculation assumptions for fabric heat loss (U-values) and thermal bridging not reflecting the reality of site construction products being used with a different energy performance to that designed the building fabric being incorrectly constructed site teams lacking skills and knowledge to build energy efficient homes. <p>The Hub's managing director Rob Pannell said: "To date evidence on the performance gap has emerged on a piecemeal basis. The Zero Carbon Hub has therefore sought to collect extensive evidence from across the housebuilding industry in order to confirm exactly what the issues are. We are now in a position to identify where the gap is more likely to occur between the designed and as-built energy performance of new homes. …