The green house effect

With its sterile, road-centred grid, 300 roundabouts and somewhat soulless new-town status, Milton Keynes has been the butt of a thousand jokes since its birth a mere four decades ago. Hell, even the cows are made out of concrete. And let’s face it, who wants to live in a place which none other than Noel Edmonds views as an object of ridicule?

Well, around 2700 new people a year, apparently. Milton Keynes is the UK’s fastest-growing urban area and is set to become its 10th largest city within 25 years. For the 220 000 who live there, it’s a perfect example of enlightened urban planning: a city in the forest, with 20 million trees and a host of unspoilt linear parks. In short, the ideal place to erect Taylor Wimpey’s first consignment of multiple-award-winning eco homes.

Taylor Wimpey worked with leading architect Rogers Stirk Harbour and Partners (RSHP) to create a development with a difference. RSHP is perhaps most famous for Richard Rogers’ ‘inside-out’ approach, with Lloyd’s of London and the Centre Pompidou in Paris featuring all services, including lifts and pipes, on the exterior. Developer Taylor Wimpey, on the other hand, is known for its safe, albeit comfortable, house designs.

Yet the two complement each other entirely. Though the modern construction materials, low-carbon footprint and bold colour palette certainly give Oxley Woods a sleek, futuristic appeal, residences are spacious and homely. Each has its own garden, as well as access to secure, open spaces throughout the development, which creates a sense of community.

Site manager Nigel Mitchell says: “The whole concept of Oxley Woods is to challenge orthodox building practices. The properties are part of the Design for Manufacture programme launched by the [former] Office of the Deputy Prime Minister and represent Taylor Wimpey’s investment in innovation and sustainability. They have a carbon footprint that is significantly less than other new-build.”

The team won the entire 3.26 hectare Oxley Wood site in the government’s Design for Manufacture competition. English Partnerships, the regeneration agency behind the contest, laid down the challenge for designers and developers to create innovative, imaginative and sustainable homes.

The entry process was a nerve-wracking one, with 221 initial bids scrutinised, pulled apart and whittled down to a mere handful. Not only did all houses have to conform to rigorous environmental standards, they also had to be constructed within a stringent budget. At least 30% had to be built for £60 000 each or less in order to help address the shortage of affordable homes in the UK.

The Oxley Woods development surpasses all expectations. It consists of 145 homes in total, 56 (or 38%) of which are to be built within these strict cost guidelines. Despite the impression this might give, we’re not dealing with a bunch of low-grade identikit properties. The overall design has been hailed as a landmark one, but RSHP has also managed to give each home its own distinct identity by varying colour and layout elements.

Part one of the three-phase project has been completed on time and within budget, and eager residents have already moved in, choosing between two, three, four and five-bedroom properties in 10 wholly different designs. Building teams are now busy working on phase two.

But paying a visit to the development, it soon becomes apparent that this is no ordinary building site. My initial suspicions are confirmed as a hefty lorry pulls up beside me, its consignment an entire flat-pack three-storey house. The homes are produced almost to completion offsite by Wood Newton, including an m&e fit-out worth £3.5 million in total.

“Everything is premade by us. We’re manufacturing panels up to 16 metres high and 3.6 metres wide. All the service routes are pre-drilled into all the beams,” says Wood Newton’s managing director John Green.

Impressively, if someone places an order for a three-storey house, Wood Newton can build it to a stage where residents can move in within six weeks.

“You’ve got four weeks from placing an order to completion when it gets to a three-storey house, including just five days to manufacture in a factory. And it takes a mere 24 hours to erect one of these to a watertight condition. The speed of erection is unbelievable,” says Green.

Each home has two distinct zones – a service zone incorporating boilers, bathrooms and utility space, and an uncluttered living zone comprising bedrooms, living rooms and dining rooms.

The team minimised the use of toxic and hazardous materials on site where possible and installed water-saving dual flush toilets and energy-efficient (A-rated) white goods.

“To achieve the BREEAM homes excellent rating, we had to be forward-thinking and do a few things such as installing low-emission boilers,” says Green.

Primarily, however, Oxley Woods’ eco credentials, which also include the maximum National Home Energy Rating and EcoHomes’ classification of ‘very good’, are down to the creation of one innovative product.

Back in December 2005, Wood Newton approached Scottish firm Rybka to provide m&e consultancy on the project. Working closely with energy-efficient ventilation system manufacturer Nuaire, Rybka took on the challenge to develop a bespoke system that would maximise energy and construction efficiencies. The EcoHat was the result.

“It’s basically a chimney that filters all fresh air entering the building and re-uses hot air that circulates through the stack, supplemented by solar energy,” explains Green. “It’s the first time we’ve fitted anything like the EcoHat as it’s a bespoke product design, but it was really simple to install,” he adds.

Even without the EcoHat, homes at Oxley Woods enjoy a 27% reduction in CO2 emissions when compared with a conventional new home of similar proportions. But this rises to 40% when Nuaire’s solution is incorporated.

In fact, residents who decide to use the EcoHat to top up energy for their hot-water systems can actually expect their emissions to be reduced by as much as half.

In keeping with Wood Newton’s approach, Nuaire adopted the prefab principle for the EcoHat base units. The systems are pre-assembled at Nuaire’s manufacturing plant in south Wales before being despatched to site. Not only does this allow for quicker installations but the systems can also be rotated for best orientation.

Wood Newton chose Hager’s flush-fit consumer units to provide accessible electrical safety, with RCD protection across all circuits to reduce the chance of a homeowner receiving an electric shock.

Mounted at 1200 mm height in the hallways, the units are accessible for both able-bodied and disabled people, helping Oxley Woods achieve its credentials under the Lifetime Homes initiative, originally conceived by the Joseph Rowntree Foundation, by reducing modifications that may have to be made as a homeowner ages.

Each board has a 100 A switch disconnector mains and two 30 mA residual current devices. The electrical circuits are split between the two RCDs so that if one trips, only half the power and lighting circuits are lost at one time. The boards have several blank ways to allow for future expansion.

Scrutiny of Oxley Woods reveals that the design has been thought out at every level to the last minute detail.

“We did a mock-up in Derby back in 2006, where we tested everything we were trying to achieve,” says Green. “That’s how we found out where we needed the cable routes going, how the EcoHat worked, where the ventilation requirements needed to be redrilled and where the ductwork needed to go. It was all sussed beforehand, and we used some 3D modelling too.”

Regular site meetings are still ongoing. “The site meetings strategy is radical,” says Green. “It’s a big completion. But with it being a one-stop shop, it’s the whole package we’re discussing, not separate m&e meetings.

“We’ve had more experience of this sort on the commercial than the domestic side, on projects such as schools and universities, and London’s Lawn Tennis Association. But the lads are getting better as they go on.

“It’s all about practical experience, essentially. We couldn’t afford to take two weeks out after the first phase and reflect on what we could have done differently. It’s a fast-track project.”

With such a host of accolades under their belts, those behind the Oxley Woods development hardly need to worry about enhancements.