The industry is in a state of blind panic over Part L, the revised energy regulations implemented yesterday. Thomas Lane explains what we now can and can't build - and why we should all keep panicking …

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This week was a big week for the construction industry. Yesterday the 2006 version of Part L of the Building Regulations, which deals with the energy performance of buildings, finally came into force.

For months now, the industry has been complaining bitterly that these changes were being rushed through by the ODPM at breakneck speed and that the industry could not possibly cope. For example, the final approved document was published three weeks ago, instead of the more usual six months, and the third-party guidance to which Part L refers hasn't been published. Then there is the computer software for checking compliance. This is vital for making the regulations work in practice, but a final program has not been formally approved, and the beta version has attracted widespread criticism. For one thing, it makes it easy to get approval for all-glass buildings, something many people expected to be killed off by the new regulations.

Interestingly, nobody is complaining about the tougher energy performance targets. "I've got no problems with regulations that drive energy efficiency but I do have a problem with the way they've been forced on the industry without an adequate lead-in time," says Derek Field, McCarthy & Stone's operations director for its northern region. He is angry that the industry has been put under this kind of pressure by a government that is struggling to meet its own carbon targets. "Because it's politically correct to say carbon emissions have been reduced they're scoring a political point at our expense," he says. "It's a completely unreasonable attitude because they don't understand the implications of what they're trying to do."

Unreasonable or not, the industry now needs to know what it has to get to grips with - and what the consequences of rushing the new Part L through will be. Over the following pages are the key questions being asked - and their answers …

So what's the rush?

Part L has been revised two years earlier than originally intended to allow it to incorporate the European commission's Energy Performance of Buildings Directive, which aims to cut carbon emissions across Europe. And the government is under intense pressure to cut the UK's emissions - recently it admitted it would not meet its Kyoto target of reducing emissions in the UK by 20% below 1990 levels by 2010.

This is why the widely expected transitional period failed to materialise. Instead, the ODPM announced that all buildings without full building control approval would have to comply with the new Part L after 6 April. Because it announced this six weeks before the deadline, it gave the industry no time to get schemes approved under the old Part L.

What are the big changes?

There are numerous changes, which add up to tougher energy performance standards overall. For example, an air-conditioned office building has to be 28% more energy-efficient than one built according to Part L 2002. Housebuilders will for the first time have to pressure-testing their product for leaks. And the whole industry will for the first time have to use computer software to calculate compliance.

Why is computer software necessary?

This is the European Union's fault, not the ODPM's. The directive requires a whole-building calculation methodology when working out a building's carbon emissions. There was provision for a whole-building methodology under the old Part L but hardly anyone used it. Instead they used the much simpler "elemental" method. All designers had to do was ensure that each building element met a minimum standard set out in the regulations. This is now history, as everyone is now obliged to use approved software to calculate compliance.

How does the software work?

Part L is divided into two sections, dwellings and non-dwellings, and there is separate software for each. Housebuilders use a new version of the standard assessment procedure, SAP 2005, that has just been released. Everyone else uses the simplified building energy model, or SBEM for short. Both can be downloaded from the internet. The key thing to remember this is only used for compliance, not modelling a building's performance. Designers design their building then enter the data into the software. It crunches the numbers and tells the user if their building complies.

I’ve got no problems with the regulations; I have a problem with the way they’ve been forced on the industry

Derek Field, McCarthy & Stone

That sounds simple enough - why should there be any problems?

The software has been developed at breakneck speed to meet the deadline. SBEM is particularly problematic as it has to be developed almost from scratch. "It's producing surprising results," says Nick Cullen, a partner at consultant Hoare Lea. The software has to tackle a fiendishly complex web of interdependent design scenarios and has certain assumptions about these built into it.

The problem is, it doesn't account for some fairly basic scenarios faced by designers. SBEM seems to spell the end of one common system used for air-conditioning and makes it easy to get thermally inefficient all-glass buildings to comply. "I think they have missed off the step of using the software to model real buildings," says Cullen. "It should have been tested for a while before production."

Credit: Corbis

Why is SBEM discriminating against some types of air-conditioning system?

According to Cullen, SBEM is prejudiced against fancoil systems. These are simple in principle - a fan in the unit blows air over pipes containing either warm or cooled water - the warmed or cool air is then distributed around the building. This type of system is the bread-and-butter of many service engineers. "Assuming you are doing calculations in the proper manner it is very difficult to get compliance using fancoils," says Cullen. "I don't think that is what the government intended."

He says the problem arises when service engineers apply best-practice design to buildings, which involves separating each floorplate into a perimeter and a central zone to account for heat losses and gains through the facade. But the SBEM model doesn't appear to account for this approach, because it is possible to get a building that isn't zoned to comply.

Cullen says that designers will have to use cooling systems that don't rely on fans, such as chilled beams. "Perhaps its time we moved on from fancoils, but the ODPM should make this explicit," he says.

Why is it so easy for all-glass buildings to comply?

"The big issue is, it is actually easier to get an all-glass building through the new Part L," says Terry Dix, director of Arup's building services division. "It makes some assumptions that are questionable." He says SBEM assumes electricity will be saved in all-glass buildings because less lighting is needed in the summer. Furthermore, it regards heat loss from the building as a good thing, even in winter, as the equipment inside will be generating more heat than the building needs, and heat loss cuts down on the electricity needed for air-conditioning. "The programme ignores the fact that people will pull down the blinds because of glare, which means lighting is still needed," explains Dix. "It also ignores the fact that engineers put in trench heating around the perimeter of glass buildings to stop down-draughts. There is a difference between SBEM and real life."

How will building design be affected by this new way of calculating building energy performance?

Greatly. Because the building's energy performance is calculated as a whole, any changes could have adverse effects on its performance. "It's not so simple now," says Bill Ireland, M&E profession director at consultant White Young Green. "It's no longer just a case of adding more insulation to improve the building's energy performance, as it may cause overheating in the summer - which means it uses more electricity for air-conditioning." In other words, the building's energy performance will have to be checked at concept stage to ensure it complies in theory, then constantly monitored all the way through the design and construction process to make sure it complies in practice. The building will be checked on completion and failure could be expensive.

Will that affect the way teams work together?

Yes. "This is a sea-change in how we design buildings as we have to integrate the fabric and services to a far greater degree than before. There will have to be much greater iteration between service engineers and architects," says Peter Caplehorn, technical director of architect Scott Brownrigg. Ireland says this means service engineers need to be involved at concept stage.

A lot of people don’t understand it so it’s going to be messy. There will be poor compliance this year

John Tebbit, industry affairs director, CPA

Ireland and Caplehorn warn that other people in the industry haven't absorbed the implications of this change. "The problem is, clients have to buy into this; they think Part L is just a case of adding some more kit and insulation," says Caplehorn. "They'll wake up if they get to the point when their building is finished and it fails."

What about calculating the compliance of dwellings - are there any problems with the software for that?

There have been no reports of problems with SAP 2005 software. However it hasn't been approved yet and the accreditation courses that people need to take before they can use the software are full. "You won't get accredited inspectors until well after the implementation date, which seems crazy to me, says Simon Clift, McCarthy & Stone's commercial director.

Because there are no accredited inspectors to check schemes, the company will have to overdesign schemes to ensure they comply when checked on completion. "We are trying to get all the schemes under way where we can. In some cases we will have to take a flyer and build to a much higher standard than we need to and even then we can't be convinced we are going to comply," Clift says. He adds this will bump up costs between £1000 and £1500 for an apartment.

What else do housebuilders have to cope with?

Homes are now subject to mandatory pressure testing to check for air infiltration. According to Mark Pharoh, McCarthy & Stone's group design manager, this means more expensive precautions against failure. "I am sealing every flat, as I don't know how well they perform until they are tested on completion in six to 12 months' time," he says.

How will small builders manage with the changes?

Having to calculate Part L compliance using software will "hit small builders hard", according to Andrew Large, the external affairs director of the National Federation of Builders. He is unhappy the usual training programmes haven't materialised this time. "It's going to be a significant challenge to their IT skills. A significant minority don't own a computer for work - if they have an email they pick these up using the computer their children use for their homework."

Large thinks small builders will have to pay specialists to do the calculations for them. "It is a recipe for chaos and I don't understand why it's happened this way," he continues. "I have written to Anne Hemming asking for a ‘light touch' regime where building control are on hand to assist rather than enforce for a year."

Is building control prepared for the change?

Unfortunately Large is likely to find building control won't be in a position to assist his members. According to Paul Everall, chief executive of Local Authority Building Control, training courses for building control officers planned for January had to be postponed because Part L hadn't been published. "Because of the late publication of the documents, those workshops will now take place between April and June so LABC will not be properly trained to enforce new Part L." He thinks big consultants will do their best to comply with Part L but the problem will be with small housebuilders and general builders. "In normal circumstances building control officers normally offer guidance to those people, but they won't be able to help as they aren't trained yet."

Will the industry comply with Part L?

According to Everall, building control officers will be in a position to enforce new Part L progressively as they get up to speed. John Tebbit, industry affairs director of the Construction Products Association, agrees. "We know a lot of people don't understand it so it's going to be messy. There will be poor compliance this year, we have to accept this is the price we have to pay for not getting it out earlier," he says. This means the mad rush has been pointless as the government won't get its hoped for carbon emission cuts as fast as it wanted.

Tebbit has a few words of advice for the next revision of Part L, scheduled for 2010. "We have got to get it better next time by taking a longer-term view, keeping the methodologies the same and keeping politics out of Part L. The most dangerous thing isn't Part L, but a minister that has to be seen to be doing something."