New model for urban housing unveiled
Prototype flexible family house built in west London has already sold and features in bid for Olympic legacy site.
Report from – Jo Smit
A prototype home for urban development has been built on a site in Fulham, west London. The Rational HouseTM is designed to Code for Sustainable Homes level 4, complies with the new London Housing Design Guide and is constructed using precast concrete.
The house has been originated by architect Robert Dalziel and engineer Tim Battle, directors of Rational HouseTM, to provide high density, low rise, sustainable homes with design and quality at an affordable cost. The prototype, which is being marketed through estate agent Jackson-Stops & Staff, is already generating interest and the design has been included in Barratt East London's bid to develop a legacy site from the London 2012 Olympics in Stratford, east London.
The standardised design can be applied to many plan and dwelling sizes, and can accommodate commercial uses. The one-off house in Fulham is a three-bedroom, four-storey unit with top floor study. The 150m2 unit, with around 36m2 of external space in the form of a courtyard and terracing, occupies a tight former car park site and has a footprint of just 9.5m by 9.5m. The design combines the flexibility and elegance of the Georgian townhouse with a contemporary focus on sustainability.
Key features of the house include:
- precast concrete is used for the loadbearing external walls, floors and stairs. The construction method means there is no need for internal steel framework, allowing flexibility to adapt a house to apartments or to mixed use
- external walls have high levels of thermal mass, being made from insulated sandwich panels using the Thermomass insulation system. The wall panels have 100mm external skin, 115mm insulation and a 125mm internal skin. External wall U value is 0.15
- triple glazed windows, with external aluminium shutters which fold into wall recesses to provide security as well as summer shading
- natural stack ventilation via the stairwell
- 1kW of photovoltaics on the roof, which also provide shading for the top floor study
- sustainable construction materials, including secondary aggregates in the concrete, recycled zinc for the roof and recycled bricks for the cladding
- two rainwater butts and low water use fittings.
Concrete was specified for a number of reasons, said Rational HouseTM associate architect Sheila Qureshi: "There is a lot of glass in the building to provide natural daylight and we didn't want to compromise that. The concrete gives great thermal mass and is sustainable with its use of secondary aggregate. It also has good sound insulation. This house has been created specifically for cities." The precast concrete panels were produced by Sterling Services of Taunton, and are connected using standard fittings. Panels can be erected at a rate of approximately one per hour, with a house shell constructed in two weeks.
Average build cost for a larger-scale development of such houses is put at approximately £95 per square foot for a shell unit, and £145 per square foot for a fully fitted version.
The prototype has sold for £800,000. Gillie Bexson, director of land and new homes at Jackson-Stops & Staff said: "We were approached by numerous prospective purchasers for 2A Biscay Road, as well as several developers who would like to engage with the Rational HouseTM team on their own projects".
Rational HouseTM has established City House Projects with partners Davis Langdon AECOM, 3DReid and Arup, to design and deliver volume developments. The two companies are working with Barratt East London on a bid for the Olympic Park site in Stratford that includes 30 three-storey home designs.
Greater London Authority interim director of housing and regeneration David Lunts has praised the design for providing much needed family housing and for its ability to sit easily in the urban streetscape. He added: "It makes excellent use of space and its technology is very simple but also very sustainable."