The building envelope makes a significant contribution to overall energy usage – therefore, tighter U-values in walls, floors and roofs is absolutely key. It’s why getting the design right from the outset is far less costly than retrofitting later. Here, Ben Cheetham, Specification Manager at Keystone Lintels, looks at the benefits of a one-piece thermally-efficient lintel including low thermal conductivity performance, buildability, improved SAP calculations and why they are up to five times more thermally efficient than standard lintels.