By the time you get back to work after Easter, the new Part L of the Building Regulations will be in effect, and the chances are you won't be ready for it. The result could be completion dates blown away, teams turned upside down – even the end of design-and-build contracting …
The industry has talked about it, agonised over it … and now it has to comply with it. From 1 April, the changes to Part L of the Building Regulations – the section concerned with saving energy – come into force. And the industry hasn't even started the reforms it should have completed months ago. Ron Decaux, director at services consultant Roger Preston and Partners, sums the revision up: "It's going to open a can of worms – we assume there's going to be chaos."

Part L2 of the regulations, covering all buildings apart from domestic dwellings, is causing the most concern. For one thing, it could spell the end for design-and-build contracts, as more detailed specifications will have to be produced at an earlier stage. Project teams will have to be rethought, and the services engineer will emerge as the new top dog. Worst of all, many completion dates will have to be extended and dozens of buildings will be late because of the requirement to pressure-test buildings at the end of the build programme. This is no form-filling exercise – failure could result in a building having to be torn apart and rebuilt.

The problem for design-and-build projects is that there is no guarantee that the contractor can produce a compliant building envelope from an architect's concept design. For example, the architect's concept could be a glass building that could never be made to comply with Part L. Lawrence Parnell, a director at Taylor Woodrow, cautions: "Clients would be well advised to take the design to a more advanced stage, because otherwise, the contractor will have to put in a price to cover the risk." This, of course, would negate the whole point of design-and-build.

Even if the contractor does take on a design-and-build contract, it may not have the capability to make the calculations necessary to show that the design will comply with the regulations. Ross French, senior engineer at services consultant Rybka, says the carbon emissions method of calculating the energy consumption of the building involves endless calculations and can involve computer thermal modelling. "You don't find many contractors who can do thermal modelling," he observes wryly.

All this adds up to a sharp rise in design costs for clients. One of the first buildings to be built with these factors in mind is the Peoplebuilding Hemel in Hemel Hempstead, designed by Richard Rogers Partnership for Stanhope.

David McAllister, a mechanical engineer working on the project with Arup, says: "Things that were not of primary importance suddenly become critical." A services system may be theoretically compliant at the design stage, but could easily fail by the time it gets to tender. For example, the rating of motors could slip a little, prior to the revisions.

Project teams will have to be reconfigured because the relationship between the form of the building and its services is so much more critical. McAllister's colleague Sarah McGowan says Part L will force architect and engineer to work closely together from the beginning of projects. "The engineer has to get on board early on. Unless you think about the issues at the concept design stage, you won't comply," she warns.

But the most dramatic immediate effects could be as a result of pressure-testing. Contracts will have to be extended because of the huge delays in finding someone to carry out the work. The only main outfits with the required test equipment are BSRIA and BRE, and they cannot possibly test all the new commercial buildings in the UK. Even so, securing a test date will be only the beginning of the contractor's problems. Taywood's Parnell sums up the headaches:

"The tests have to come very close to the end of the programme. If there is a problem of non-compliance, there could be significant disruption to the completion date." The potential for delay comes from all sides – Parnell describes how one Taywood test in Manchester was delayed for three weeks because of high winds, which could have corrupted the results.

If the building fails the pressure test, it will almost certainly fail to meet the contract completion date, even if it is extended, because the building will have to be ripped apart to remedy a problem. And even if it passes, the test will have been held at a critical time in the programme, when everyone was rushing to get the building finished – and all the workers would have had to have been cleared out to conduct the test.

Ensuring the building passes will be vital to a project. Parnell says: "Clearly, we will be impressing on our design teams and contractors the importance of sound detailing and programming in the testing." This will become even more critical after September 2003, as the air leakage rates will then get tougher still.

The face of the industry will change as small businesses struggle in the new climate. Decaux believes they will be hit hard by the complex U-value calculations required to prove compliance. All the large consultants have developed software to carry these out, and have qualified engineers who understand the sums. These engineers will be deemed a "competent person" by the regulations and will be allowed to certify the figures. However, the smaller firms may not have a competent person on their team, so the local authority's building control department will have to check the sums. However, Decaux warns: "Building control departments are not qualified to check the calculations for building engineers." Because of this, some defects will slip through the net.

Local authorities are quite candid that they are not ready for the new Part L. Peter Hamilton of the London Borough of Tower Hamlets admits: "We're still struggling to be ready, because of the far-reaching nature of the changes. We are getting to grips with it as we speak."

The other problem he faces is sorting out what the definitions in the regulations actually mean, and dealing with the constant amendments and changes to them. "We have to remain glued to the DTLR website these days to keep up," he says.

Housebuilders are the only ones who seem quite chipper about the impact of the regulations, which is surprising given their reputation for conservatism. Part L1, dealing with dwellings, is straightforward as there is no air-leakage testing, and the calculations to prove compliance are easier. Tony Hillier, managing director of Hillreed Homes, sums up the feeling: "It is less disturbing than we thought it would be. The changes aren't all that significant, except that there is a cost impact."

Hillier can continue to build with brick and block; all he will have to do is use better floor insulation, low-emissivity glass and the installation of condensing boilers. Housebuilders will not have to pressure-test buildings, but will have to ensure their buildings are airtight by complying with a supplementary publication to the main regulations.

Despite the mayhem that seems to lie ahead, most people are agreed the new Part L is a good thing. Rybka's French expects his practice will pick up more work and is naturally pleased about this. Arup's McGowan speaks for most people when she says the regulations are good for the reason they were introduced; to save energy. She also has some crumbs of comfort to offer after her experience with the Stanhope project: "It's not as scary as it looks – once you have worked through the calculations, and done a couple of buildings the method is reasonably easy to follow."

For everyone's sake, let's hope she is right.

Under pressure: Passing the airtightness test

Developer Akeler has been pressure-testing its new buildings for airtightness since 1996, and has considerable experience in this area. Marcus Boret, the firm’s construction director, says of the testing procedure: “Just turning up on a Friday and testing the building is hopeless – it won’t pass.” The process could change the way buildings are designed. For example, Boret says sealing an insitu concrete frame with a curtain wall is much easier than sealing a steel-framed buildings with standing seam roofing. The main area where leaks occur is the interface between components, so all the interfaces need careful detailing, particularly the junctions between cladding elements and the walls and roof. Boret says there needs to be some overlap between these elements, and allowance has to be made to accommodate the expansion and contraction of different materials. Good construction practice is also critical to airtightness. Akeler employs a consultant to ensure that all the components installed by trades join seamlessly. Quality control needs to focus on surfaces and junctions that are not visible within the finished building. Penetrations of external and internal surfaces by elements of services such as pipework and electrical cabling or conduits also need to be carefully executed and sealed. Boret believes getting the different trades to work together to prevent interface leakage is “where the industry will fall over”. Getting the building airtight is something Boret knows can be done with the right approach, but he thinks getting someone to test it will be almost impossible. His solution is to invest in a new testing outfit called BPT, set up on the back of the new regulations. The company will offer advice from a building’s inception through to final testing to ensure that it will pass. He sees this as not only a good business opportunity, but a way to ensure Akeler’s own developments are tested promptly.