The delayed changes to Part L have come into force at last, but debate rages over whether they go far enough and what their impact on the housebuilding and insulation industries is likely to be. Chris Wheal examines the drawbacks and the benefits

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Ask a housebuilder, an architect, an insulation manufacturer and an insulation distributor about the recent changes to Part L of the Building Regulations and you get a consensus that the new rules have only gone part way.

The first UK government consultation on zero carbon was back in 2006. The Construction Strategy agreed zero carbon houses as a target by 2016. The figure in this first of a two-step approach was a mere 6% cut in CO2 emissions. Add to that the delays - Part L changes were to be implemented last October but were delayed to April 2014, and the software for calculating a home’s Standard Assessment Procedure (SAP) only came out with the regulations - and you can see why fans of better insulated homes are unhappy.

Peter Caplehorn is technical director at architect Scott Brownrigg and a member of the Building Regulations Advisory Committee. “The amount of performance improvement is taking us off track to get to near zero, or low carbon, by 2016. We are about 40% adrift of where we should be, and that’s a pity.”

Andrew Orriss, head of business development at specialist distributor SIG360, is equally concerned. “We are disappointed the standards have been diluted to the degree that they have. It was unnecessary. The 6% aggregated in England and 8% in Wales was unnecessarily low. I didn’t think there was any reason not to pitch for 25%. The technology and knowhow were there. The build costs for code 5 and code 6 homes have dropped considerably over the past five years.”

There were reasons for taking a smaller step this time round, argues Mike Ormesher, technical director at Knauf Insulation, but he says that will mean a huge leap forward with the next revisions. That requires a change of approach. “We could have done a lot more but the pressure is on the housebuilders. A radical change would have been harsh on the housing industry given how we build today. We need to engage a lot more intelligently with housebuilders to recognise where we can make the next step changes, which will need to be significant,” he says.

The scaling back was all down to pragmatism, agrees Jonathan Moss, group sustainability and technical manager at housebuilder Redrow. Housing is only just coming out of recession and anything stronger would have been a huge cost to bear, potentially stopping recovery in its tracks.

“The regulations were pretty much in line with what the consultation suggested,” he says. “We’re glad that fabric energy efficiency is coming in. That was a good idea proposed by the Zero Carbon Hub. We were surprised there was a bit of relaxation in there, but it may have been too big a step on some of our house types, so that relaxation was welcome.
“When I first heard about the regulations, they were talking about very low U-values. We were a bit shocked. But now the tools are out and there’s the relaxation of 15% of the fabric energy, it’s not that bad. The fabric energy efficiency does focus the mind on the fabric first rather than using any bolt-on renewable technologies.”

Despite the new Part L regulations being relatively benign, many builders, fearful of tougher rules, got their planning applications in early, allowing them to build under 2006 rules without the threatened higher build costs. The rules led to what Orriss calls a “gold rush” of planning applications. “That is disappointing, not just as a supplier but as a consumer looking to buy an energy-efficient home,” he says.

Caplehorn agrees. “I come from the position that says when you change the regs, everybody changes. A huge amount of applications have been pushed through because everyone wants to avoid upgrading their building’s performance. That is highly regrettable. We don’t get it in other areas of society. We don’t get people rushing to buy cars with lesser performance simply because they might go faster. In better performing buildings, people will spend less on energy, they will be more comfortable and those buildings will perform longer at that level.”

I am convinced that the capital costs of enhancing a house’s performance is peanuts compared with a house’s market valuation

Peter Caplehorn, Scott Brownrigg

Moss can see the issue from the other side. “Part of the reason so many rush through planning applications is that we want some surety, and if you’ve got compliance tools coming out on the day of implementation, it doesn’t leave much room for anybody to assess the impact of the regulations and make a judgment call on whether or not they need to get an early application in,” he says.

Ormesher suggests this will be the last time housebuilders get let off. “The latest revision to SAP has only just come out. It was a very difficult thing to do. The supply chain is vast and the government didn’t really understand the implications. The housebuilders had to say ‘enough is enough. We can’t possibly make these changes in the time given to us’, which is why we need to engage more intelligently. Because, next time, we won’t be able to have incremental changes,” he warns, Caplehorn dismisses the cost argument. “I am convinced the capital costs of enhancing a house’s performance is peanuts compared with a house’s market value,” he says.

He is evangelical in wanting consumers to reject lower-build-quality homes. “We should be cultivating purchasers to be more concerned about performance. There should be a moral impediment not to buy a carbon-guzzling house. There should be consumer resistance to being sold inferior products,” he says.

But not everyone is heading for the lowest common denominator. Moss says Redrow is considering adopting the tougher Welsh standards across the UK. That means changing its standard wall cavity from 90mm to 150mm. “In Wales the backstop U rating is no longer going to be 0.3 but 0.21, so we have to build a different wall type than we do in England. Maybe we’ll just bite the bullet and have one standard wall at 150mm cavity across the UK. We have a cost exercise going on now looking at that,” he says.

Adapting to the new Part L

There are other positives to the new Part L regulations. It is widely expected they will lead to better quality workmanship on building sites. Orriss points to the rules looking at thermal bridging and air permeability. “Both are attention-to-build-quality details. They will close the gap between as-designed and as-built because they are parameters that were ignored before,” he says.

Ormesher flags up leakage too. “The changes go a long way to try to improve workmanship on building sites, which is a first for the Building Regs. If you look at leakage, down to five cubic meters per square metre per hour, that is a clear signal we need to improve workmanship.”

“The drive towards real performance, which Knauf Insulation is very active in, is going to be a clear way of identifying shortfalls in building techniques.”

There are likely to be hiccups with the new regulations. While the ability to blend technologies and solutions in different applications still exists, it is more complicated. That may mean only the big firms have the time and money to invest in working out how to do it well. Smaller builders, using smaller architects on lower fees, may end up using backstop figures and spending a lot more per house. Orriss warns: “If you just use the backstops, the defaults, it is challenging - and for challenging, read expensive.”

He adds: “People in the know will be able to blend their options and take advantage. Many small architectural practices working on tight fee schedules will default to something they know will work, rather than something that’s in the best interests of the builder at the lowest possible costs.”

Complex contractual arrangements may be counterproductive, says Caplehorn. “Some parts of Part L are far too complex. Everybody always has trouble with consequential improvements. The concept is straight-forward - if you’re modifying an existing building you want to divert some spending on areas you weren’t going to touch. But it’s not that simple. They have to be technically, economically and proactively viable.

“Each one of those words is an interesting concept in a contractual situation trying to make money or be professionally correct. They can be challenging to get agreement. You need to work as a team.

But in this industry, people are often more keen to stand on principle rather than get to a solution. It is the devil’s own job to get people to work together as a team. Everybody starts off not trusting everybody else.”

We talk about sticks and carrots in different markets and what drives innovation in this market is a big stick

Mike Ormesher, Knauf Insulation

Insulation manufacturers could help - good data about products in an easily comparable format is a common suggestion. Detailing how products should be used in different applications and providing examples of products in situ is another. Coming on site and random testing to check the products have been installed correctly is one more.

Moss has another suggestion: “One of the things we talked about in the Zero Carbon Hub was identification of product. With plasterboard you can go on site and pretty much know the pink board is your fire board, your green board is your moisture board, your blue board is a sound-block board … but with insulation each manufacturer has their own colouring and labelling. It would be good for the industry to agree a performance identification system,” he says.

Knauf Insulation’s Ormesher suspects it might not be easy as it sounds. “They have different thicknesses, densities and applications. If you were to work out a matrix of the different applications on site and the different U-values, you would start to find stress points where you couldn’t possibly colour code the products to do the same applications. The only way to do something like that would be through the Construction Products Association, where you could get lots of competing manufacturers who don’t normally talk to each other into the same arena. The reason it hasn’t been done is that it isn’t that simple,” he says.

What everyone wants is the possibility to mix and match products and solutions through design and build to meet the new regulations without simply ticking boxes and adding hugely to costs.

Orriss says: “We favour the opportunity to blend things, simply because that allows the housebuilder to get the best value. We don’t want to support rapidly increasing house prices because build costs are going to shoot up. Some of the things we do could be considered counterintuitive in that we can sometimes reduce the amount of insulation in our customers’ dwelling to make it more cost-effective but still meet the standards. We know how to do that, so shouldn’t we share that with customers? Anything else would limit architectural freedom. You will potentially find houses with lots of wall and very little in the way of windows. We need interesting buildings to look at too.”

Caplehorn takes the same view. He argues that with the growing adoption of Building Information Modelling (BIM) architects will increasingly be able to check buildings are following their original designs and meeting the standards. “When BIM has been rolled out for a few years and you can walk onto site with a tablet and use augmented reality to compare what is on site with what is required, you are in a stronger position,” he says.

Moss reckons the changes may attract more people to the industry. “It’s a science now. You have thermal issues, air issues, district heating. It’s a much more interesting proposition for people to enter the industry.”

Playing catch-up

Ormesher is optimistic that British buildings will get better insulated and the Part L changes, although minor, are an important step in the right direction. He says he supplies higher-level products to UK niche builders constructing code 5 and 6 homes; the rest of the industry will catch up eventually. “I cover the Nordic countries where the U-values are significantly lower than anywhere in the UK - wall U-values of 0.11 and 0.12. We are 10 years ahead in the Nordic countries. We could provide anything the UK needed for tougher standards, and we can go further and work on passive design houses, which we do effectively in Germany.

“There is a significant cost involved in a more efficient product and housebuilders probably wouldn’t buy it because they need to compete with other housebuilders. We talk about sticks and carrots in different markets and what drives innovation in this market is a big stick.”

This feature was sponsored by Knauf Insulation.