Sustainable housing: The big beast stirs

Britain’s biggest housebuilder is finally climbing aboard the sustainability bandwagon. But is Persimmon really going green – or it just playing the chameleon? Paul Howard finds out.

If the construction industry in general is perceived to be broadly conservative, albeit with a growing number calling for reform, the private housebuilding sector could easily be seen as the reactionary right.

Main contractors and specialists are increasingly happy, like David Cameron, to embrace green issues and to distance themselves from a historically accurate, but rather unflattering reputation. Yet the persistent resistance of housebuilders to innovation and their continued denial that there are any problems with the old way of doing things makes them more akin to Norman Tebbit.

The result is a sector where modern methods of construction are notable mainly by their absence and supply chains are as long and wasteful as ever. And, in spite of all of this, it’s a sector with profits the rest of the industry can only dream of.

Which begs the question: when – if ever – will the environmental imperative that is being felt so keenly elsewhere in construction begin to have an impact in private housebuilding?

The answer may be sooner than you think. Already, there is a small but significant number of specialist companies making a success of tapping into the niche market created by those who are prepared to pay a bit more up front for a house that is green.

And now Persimmon, the country’s largest housebuilder, has embarked on a project to determine for itself the merits and marketability of various different approaches to green house construction.

The project is based on a housing development at Irlam, near Manchester. It involves the construction of four different kinds of ‘eco-house’, all with different angles on how to meet the sustainability agenda.

Different philosophies

One reason for this variety is to allow the company to assess different materials and different philosophies. “Not everything that we’re doing here will make it onto the market place, but we want to test things,” says site manager Albert Hassall.

But there is another reason too.

“We want to offer a range of houses and approaches,” adds Hassall. “We don’t want to offer just one ‘green’ house to the market – we want to offer several at a range of prices.” Hence the typically ‘new house’ names attributed to the various designs: Thirlmere, Buckingham, Dore and Ure.

The houses have other names as well, however, names more closely associated to their specific green credentials (see below).

First comes the EcoHome, built with the aim of attaining an ‘excellent’ rating from BRE’s EcoHomes. Then there is the TechnoHome, which strives to combine sustainability with cutting edge technology, both in terms of what’s on offer to the prospective buyer, and in controlling the house’s energy consumption. These are joined by the LifetimeHome, designed to adapt to a family’s changing needs over time, and the self-explanatory EnergyEfficientHome.

Waste reduction

The general benefits of all these approaches have been pronounced. Waste has been reduced dramatically and build time has been cut, although not as much as it would be next time these methods are employed.

“Programming is hard to do,” says Hassall. “We’d probably build these houses twice as quickly now.”

“This project has opened our eyes a bit,” adds David Broadbent, regional chairman. “We’ve worked closely with WRAP and undertaken a very close examination of our supply chain and we’ve found a range of new products with a higher recycled content and some that are cheaper than those we were using before. We’re already rolling them out across the business.”

The next big question, however, is when will these houses become the norm, rather than the exception? The Irlam development represents just four out of Persimmon’s anticipated total of nearly 17,000 completions this year.

Not yet, seems to be the answer.

“If you’re talking about people paying an extra £5,000 then we’re not there yet, and it will take some time,” says Broadbent. “But at least now we’re talking about things we’ve never talked about before.”

“In terms of the ability of the marketplace to support these houses, it’s down to two things,” he adds. “The first is the payback period for the extra initial cost of installing solar PV, efficient boilers etc… Purchasers need to be able to see this in terms of pounds, shillings and pence and the time it will take.”

So what is the mark-up likely to be on ‘green’ houses?

Broadbent is coy on the actual figures. “It depends on the different features used on each house and the value that others put on these things.”

He is more open about the extra cost of installing these items, however. “It’s probably between an extra 10% and 20% compared to a normal house.”

A tangible example from Irlam is the cost of the PV tiles used on the EcoHome.

“We’ve used 40 panels, sufficient to generate 0.92kWmax/hr,” says Hassall. “In one year, this would generate 690kW towards yearly consumption and as this isn’t all at the time of year when you need it most, the house has two electricity metres, one for electricity in, one for surplus electricity sent out to the national grid.”

Beneficial though this may appear, the cost of this arrangement is £7,000. Still considerably more than can be recovered in energy efficiencies over the short to medium term. “PV tiles are too expensive yet for people to make their money back from them by savings in electricity bills,” says surveyor Derek Beesley.

“The second factor is the general and growing sense of social responsibility that everybody has to do their bit,” adds Broadbent.

This influences purchasing decisions, but on its own is not enough. “Housebuilders are unlikely to spend lots of money on improving the specification of houses if there is no likely increase in sales. But once they do see the benefits in terms of sales, then the changes they can effect will be faster.”

This process of change is likely to be speeded further by the involvement of private housebuilders in social housing for the first time, where the compulsion to meet green building standards in order to receive government money has recently been strengthened – a move welcomed by Broadbent.

“It would make all developers sit up and think if the only way to get land is if you do X,Y and Z, and being involved will help our familiarity with the supply chains and processes needed to build these kinds of houses on a wider basis. We’ll then be able to take these into the private sector. We’ll have a part of the business that knows how to achieve these standards and will know where to get the staff and the trades.”

Even then, Broadbent is aware that sustainability is a wider issue than just the houses themselves.

“A green house meets part of the sustainability agenda, but if we were to do it properly we’d have to look at the whole housing scheme in the wider context of transport networks, waste generation and collection services or communal wind turbines. In Irlam we’re really demonstrating what you can do within a traditional development. To go that next step you’d have to start involving the local authority, the health authority, the waste collection services. In this context Persimmon is just one piece in the jigsaw, and it would be better for this wider agenda if there was more and wider co-operation.”

“It’s fair to say housebuilders are slow to change,” he concludes. But then perhaps government and consumers aren’t that quick to encourage innovation either.

The EcoHome

A timber framed, detached house built using PrestoPlan OSB panels with a vapour barrier and insulation on the outside, enclosed in a traditional brick fascia. The house also features lambswool insulation, 40 photovoltaic roof tiles and a micro combined heat and power generator. The SIP (structural insualted panel) roof is made by Kingspan, the windows and skirting boards are softwood. It has underfloor heating, Rainman rain water recycling and kitchen units made from 95% recycled material.

The TechnoHome

Also detached and with a steel frame filled with Thermonex concrete panels - made off site. There is a cellar fully kitted out for use as a media room, a gym, a shower room and a utility room. Internally, the house consists of metal framed pods with concrete walls. There is a closed-circuit geo-thermal pipe laid in the garden plus a ground-source heat pump, which should heat all the hot water. Other features include grey water recycling and a centralised computer system, which can be used remotely to control all services in the house.

The LifetimeHome

Features a high degree of offsite construction to reduce the materials used and waste generated on site. There is an unfitted basement, although all the plumbing and ventilation is in place to install a kitchen and bathroom, facilitating later conversion into a granny flat. More flexibility comes from the use of Promonta blocks that can be cut easily and don't require the use of lintels, and a loft space designed for everyday use. The concrete bathroom pod was installed compelte with tiles, mirrors and all plumbing; the external bricks came as cladding panels and there is a wind turbine.

The EnergyEfficientHome (pictured above)

Another timber-frame house, this time with cement particle board and pre-insulated. This is a more rigid design that doesn't need the two-week settling-down period of the EcoHome. Outside these panels there is a cavity and block wall. The SIP roof comes from Donaldson. There is also an air-source heat pump, the pipes for which are located in the ceilings. The prefabricated floor/ceiling panels come with pre-cut grooves to accoommodate the pipework, which will provide heating for water in winter and cooling for water in summer.

[Contract Journal, 11 October 2006, pp 22-23]