The document provides information on thermal regulations in England, including details on Part L of the Building Regulations which specify energy efficiency requirements. It outlines the approved documents that contain technical guidance, including L1A, L1B, L2A and L2B. The regulations require certain maximum U-values be achieved for insulation depending on the type and location of the building and construction element (wall, floor, roof). U-values measure heat loss and insulation performance, with lower values indicating better insulation. The regulations also reference tools like SAP and SBEM used to assess energy efficiency during design and for approvals.