Flexible friends

Rather than focusing on one area of innovation for Hightown Praetorian Housing Association's (HPHA) Homes for the 21st Century, architect Briffa Phillips considered three areas of house design. "We looked at sustainable design and ways of improving the internal environment, which in turn led to the consideration of modern construction techniques," says architect Matt Briffa. This broad analytical approach helped the project gain Housing Forum demonstration project status.

The principles of lifetime homes helped determine the internal layouts of the 15 HPHA three-bed homes to be built in Hemel Hempstead and Aylesbury next year. "HPHA wanted a prototype home that was flexible enough to accommodate a number of family groupings over a long period," says Briffa. In providing flexibility the architect was keen to avoid using movable partitions. "We have used fixed walls to save the HPHA the time and inconvenience of physically configuring homes in the future," says Briffa.

Concrete floors, fixed gypsum blocks and concrete spine walls also allow for a high level of sound insulation and help define private space, says Briffa.

"We have tried to provide housing with areas of separate space. We wanted to provide a home that allowed an elderly relative or young adult to effectively live on his or her own," he says.

Lifetime features include a downstairs bedroom to accommodate residents with limited mobility and a ground floor flexible space that can be converted from an office into an en suite shower or lift. Another flexible space upstairs can also accommodate a computer, thus freeing living areas of home office clutter.

The homes will feel very light and spacious because the architect has created two galleried openings. There is one two-storey void adjacent to the stairs, which allows light from a rooflight to reach the heart of the house, while another larger void in the dining area allows the installation of a double-height south-facing window. This provides solar gain and extra light for downstairs living areas.

The design of the homes' external envelope was determined by the objective of lowering tenants' running costs and reducing tenants' energy use by 20%. Chris Twin, an environmental consultant from Ove Arup, advised the project team that heat loss would be reduced if the overall external wall area was less than 50 m2 leading to a better SAP rating. To achieve this, Briffa Phillips reduced the house height to one and a half storeys to the eaves and utilised the roof as a habitable space. This dictated that roof panels be used rather than trusses and joists. The roof panels, manufactured by Dutch company Opstalan, also have fixings for solar panels.

The external walls will be constructed using the Structherm Fastrack system of insulated cementitious composite panels. Cladding can be brick, tile, timber or prefabricated panel so that future homes can be designed for urban, suburban or conservation areas. "In terms of innovation the design is doing a lot in a way that won't upset aesthetic judgement or the planners," says Briffa. The architect has also designed the homes so they can be stand alone, part of a terrace or semi-detached. As a terrace, the homes can also be staggered to bring variety.

Everybody involved with the project says that the level of innovation achieved would not have happened without partnership. "When you're going for a house type that's not the norm using methods that aren't the norm you need partners who are willing to get round the table and have a free-for-all discussion," says Chris Burr, who worked at contractor Bickerton on the project, and who is now at CJB Construction Consultants. "No single design team can have knowledge of every new product. Keeping pace with technology is difficult," he says.

By working together, the project team considered and budgeted for seven methods of build. Impossible without partnering says Burr.

"In traditional forms of procurement it's not in the interests of any party to change their initial design or method of build. In partnership everybody has to think differently. Partners just can't take up their own positions - they must take the wider view."