With changes to Part L coming into force on 1st April, contractors will soon find out whether they are adequately prepared
The government's changes to Part L of the Building Regulations will touch virtually every sector of the construction industry. Nick Raynsford's decision to make buildings greener will change the way buildings are constructed and will affect the contractual relationships between builders, clients and architects.

No building product will be made obsolete by Part L. There was initial speculation that masonry construction would struggle to comply, but intense industry lobbying ensured that the Part L documents didn't favour the use of timber over bricks and blocks. Designers will have to think carefully about how materials are used, though. Fosters and Rogers will have to curb their enthusiasm for vast glass elevations, for example, as the use of air conditioning will be restricted.

The real challenge for builders will be to maintain the levels of workmanship required for the finished buildings to comply with Regs. Tests for airtightness will trip up those cutting corners on site. Housebuilders are exempt from pressure testing but contractors working in the public and commercial sector are not. They will have to pay for the tests and carry out remedial work if the buildings fail.

Contractors will also have to bear the cost of delays in finding an organisation capable of carrying out pressure tests. Currently, there are only two - the BRE and BSRIA. The tests also have to be carried out with the project more or less finished, which means any delays in testing will affect completion dates. Taywood has already experienced such a delay when a test was held up for three weeks because of high winds, which could have corrupted the results.

Added to these costs for the contractor is the extra expense of making the complex calculations that ensure buildings comply with Part L. In the end it will be the clients that absorb the costs of compliance and from now on contractors offering guaranteed maximum prices to clients will become a rarity.

The new Part L will change the relationship between client and contractor. Detailed design and specification will have to be done at en earlier stage, with architects working much more closely with services engineers. This could potentially spell the end of design-and-build as we know it today, as there is no guarantee that the architect's concept designs can be built by contractors to comply with the new Regs. If the designs are not taken to a more advanced stage by the architect the contractors will charge the clients more to cover the risk of inadequate designs.

In the long-term the changes in Part L could be a blessing. Workmanship will be improved, buildings will be more sustainable and cost less to maintain, and the construction industry will have done its bit to cut the UK's carbon dioxide emissions. A successful transition to tougher energy standards may also encourage the government to tackle the real source of carbon dioxide - that is the existing buildings that make up 99% of our built environment.