The DETR's proposed changes are contained in the Interim Draft of Approved Document L, published this week. The document incorporates amendments to the original proposal after last year's public consultation.
The draft Part L will be published as two documents: Approved Document L1 for dwellings and Approved Document L2 for other buildings.
Under the proposals, buildings will have to be better insulated: U-values for walls, floors, pitched roofs, windows and frames will all be tightened. The DETR refers to these new standards as "a compromise made in the light of consultation".
If doors, windows and rooflights are replaced in existing commercial buildings then they must comply with the new Part L rules. For domestic dwellings this requirement has been relaxed so that only replacement windows and boilers must comply.
For non-domestic buildings, the regulations propose to limit overheating caused by the sun, control ventilation better and provide for more comprehensive provision of operating and maintenance manuals and energy meters for buildings.
The new regulations have been relaxed for historic buildings, portable buildings and others that are not used a lot.