One of the most radical aspects of the proposals is that traditional house construction methods could become a thing of the past. The proposed increase in the insulating performance of the building fabric could mean the end of brick-and-block construction. “We are steering towards a greater use of timber-framed units,” said one senior DETR spokesman, "the [proposed] regulations are likely to be easier to achieve using steel or timber-framed construction”.

Housebuilders have given a mixed reaction to the proposals. The Traditional Housing Bureau has moved swiftly to reassure housebuyers that Part L requirements can be satisfied with masonry-based solutions. This view is echoed by Peter Hawkey, director of innovation at Linden Homes. He says: “I don't think it’s the end. We are in discussion with block and insulation makers about using better-quality products.” Cliff Fudge, technical director of block manufacturer H+H Celcon, said: “For manufacturers, the proposal sets down the challenge to create innovative solutions across a wide range of product areas.”

Unsurprisingly, the proposals have been welcomed by the timber- and steel-frame industries. Geoff Pitts, chief architect at the Timber Research And Development Association, says: “Frame systems will be the easiest way to comply with Part L. There will be more variety in the frame sector.”

However, there was concern that frame manufacturers would not have the capacity to meet the increased demand. “At the moment, timber frame only accounts for 6% of new-build homes,” said a spokesman for the House Builders' Federation. “To move this to 75-90%, as we estimate the amendment requires, will be difficult within two years.”

The manufacturers deny that capacity is a problem. John Cadwallader, managing director of Beazer Partnerships’ Torwood factory in Scotland, says: “We’ll set up more factories to deal with increasing demand.” Mark Gorgolewski of the Steel Construction Institute says: “It wouldn't be difficult to significantly increase the capacity in steel-frame production.”

There is some concern that a rush to embrace timber frame could lead to a drop in quality as cowboy manufacturers jump on the bandwagon. To prevent a return to the early 1980s, the Timber & Brick Information Council has launched a quality assurance scheme called the Q-Mark. The scheme will cover the design, manufacture and construction of timber-framed buildings.

The big break for housebuilders using traditional brick-and-block construction is the proposed improvement in the method of calculating of a building’s heat loss. The new version takes into account the performance of a dwelling's heating system, which will give designers more flexibility. Contractors will be allowed to use a slightly less arduous set of U-values if they install an efficient gas-fired central heating boiler with a seasonal efficiency of more than 75%. However, if a less efficient boiler is used or it is to be fired by oil or mains electricity (and so will emit more carbon), they will have to meet the full U-values.

The other proposed calculation change calls for the existing SAP energy rating method for calculating the energy rating of dwellings to be replaced with a carbon index. This will again allow flexibility in design.

It is not just central heating boilers that are targeted under the proposals. Installers of central heating and hot-water systems for housebuilders will be expected to certify that the systems they have installed have been adjusted “to achieve their potential for energy efficiency”. And installers will be required to supply occupiers with all the information to maintain the system at its most energy efficient.

On the theme of efficiency, lighting, too, is being rethought. In a draconian move, builders will be expected to provide a certain number of light fittings that accept only energy-efficient bulbs.