Thermal insulation, recycling and water conservation are old news, says Chloe Stothart. In the battle for high sustainability ratings, the real game is outside the door…

There can’t be many new-build city flats that come complete with a park, allotments, two ponds and a family of ducks, but Bromford Group’s Cross Street scheme in Wolverhampton has all these. These facilities have not only made the development more attractive, they have made it more sustainable, too.

In the sprint towards zero-carbon housing, plenty is said about how buildings can be constructed to particular Code for Sustainable Homes ratings, but there is little emphasis on the environment outside the front door. This is a mistake. With ecology the third most highly weighted section of the code, worth 12% of the total score, a homes’ surroundings can significantly affect the rating of a development.

Cross Street was designed under the old “Eco house” rating system, which promoted low energy and water use. Thanks to thick insulation, a biomass boiler and south-facing rooms, the homes consume 2kWh of heat rather than the usual 8-10kWh. They also contain features such as flow-restricting taps, low-flush toilets, recycled kitchen units and paving slabs made of plasterboard waste. Under the Code for Sustainable Homes the development would be likely to achieve level four or above. However, the inclusion of the eco park puts the scheme 10 points above the threshold for an “excellent” BREEAM rating.

Gavin Summerson, a senior consultant at BRE Global, says the aim of the ecology section of the code is to minimise the impact of development on sites and enhance the biodiversity of their surroundings.

Some ways of reducing the impact of a scheme are to choose a site that is of limited value to wildlife, keep the footprint small and protect existing features. Meanwhile, an ecologist can help create new habitats for wildlife and improve plant diversity, too.

The Cross Street scheme follows many of these guidelines. The original site contained little wildlife, mainly consisting of old garages, weeds and a demolished church. The eco park is designed to attract birds and insects through the choice of plants such as fruit trees that provide food and habitats. The park also plays a role in the development’s drainage and in keeping the site cool.

Water company Severn Trent set a maximum run-off limit for storm drains of 13 litres per second, as it felt this was the most the sewerage system would be able take. To this end, the water flow has been strictly controlled throughout the development. “We have tried to stop virtually all the water going out of the site,” says architect Craig Anders, partner at Cole Thompson Anders.

The drainage system starts with the green roofs. These slow down the speed at which water runs off and directs it towards water butts to be used for car washing and gardening. Excess water goes into “stormwater alteration modules” and one of the ponds, which can take up to 68m3.

The site is also exceptionally green, with flora and fauna in every conceivable space. Pergolas covered in trailing plants overhang the car parking spaces and entrances, there are small areas of trees and plants scattered around the car park and beyond them lies the eco park. “There is very little hard surface left. The greenery keeps the gardens, cars and buildings cool and reduces the urban heat island effect, which means you have a cool site,” says Anders.

Maintenance of the garden was an important consideration, since housing associations do not have large sums to spend on this and residents cannot afford huge service charges. The team used low maintenance materials, including larch cladding and aluminium guttering, as well as hardy plants. It also hopes that residents will form a gardening club and play a part in keeping the park in shape.

David Roobottom, senior contracts manager at the Bromford Group, admits it is too early to say whether this will work, as the residents only moved in a few weeks ago. However, the council allowed Bromford to select residents from its housing register who had an interest in the ecological aims of the scheme. “Given the way the letting was organised we are hopeful there will be a good take up for community gardening,” he says. “We also have a permanent on-site presence to ensure we do not have the typical shopping trolleys in the pond problem,” he says. “Any issues with customers not looking after the property should be nipped in the bud.”

While the great outdoors might not be a big aspect of housing project design right now, it is going to get more important in future. The Housing Corporation wants the schemes it funds to meet some of Cabe’s Building for Life quality standards. These include putting homes close to parks and playgrounds and including features that reduce the environmental impact of schemes. “Other housing associations will have to look at external areas more extensively over the next couple of years,” says Roobottom. “They will have to pay more attention to this because funding will be dependent upon it.”