Modular construction: social housing

29 March 2016

Lower build costs and energy savings are promised by a modular system being showcased to UK housing providers, as Dr David Kelly explains

With many local authorities resuming the construction of social housing – or investigating the practicalities of doing so – a new housing system that offers rapid delivery of affordable, quality homes with low running costs could offer a very timely solution.

One such candidate has been brought to the market by Swiss company Üserhuus and British partner Tigh Grian, an organisation that works to reduce fuel poverty and maintenance costs in affordable housing. To demonstrate and further test the new system, 2 semi-detached show homes have been constructed at the BRE Innovation Park near Watford, which can be visited by anyone with an interest in housing delivery.

At the heart of the Üserhuus Homes are factory-made 4.9m x 11.4m single-bedroom apartment modules, manufactured in south Wales using a structural insulated panel system (SIPS). These modules can be combined to form homes of 2 to 5 bedrooms to meet particular local housing needs.

Figure 1: The semi-detached Üserhuus Homes are built to the Scottish Building Regulation Gold Standard	Figure 2: The units are assembled to create the 2 homes in a process that was completed in less than 1 day

Rapid construction

The modules take 6 weeks to construct in the factory, a day to assemble on site and 1 or 2 weeks to make ready for the occupants. This is half the 16 weeks needed, on average, to build a new home using traditional site methods. The demonstration Üserhuus Homes took just 8 hours to assemble on site – a process that can be viewed in a time-lapse video on YouTube.

The units are transported by lorry and laid on pre-prepared foundations, arriving on site fully serviced and decorated, with kitchens, bathrooms and windows fitted, walls painted and LED lightbulbs in place. With Energy Performance Certificate B ratings, each unit is fully insulated and heated using a whole-house mechanical heat recovery ventilation system with wall-mounted electric panel heaters.

The Üserhuus units can be assembled into buildings of up to 5 storeys in detached, terraced, tenement, semi-detached and 4-in-a-block configurations. This offers local authorities and other housing providers great flexibility in the delivery of low-cost, energy-efficient homes, without compromising on good design and comfort.

They also demonstrate excellent overall affordability, with calculations indicating costs of less than £1,000/m2, offering housing providers an efficient use of development finance and the opportunity to generate revenue streams rapidly.

The construction and finishing of the SIPS units in carefully controlled factory conditions delivers a consistent quality that gives the assurance that maintenance issues and costs will be minimised.

With its high levels of insulation and energy-efficient lighting and heating, the basic home has been designed to deliver very low annual energy bills – estimated at £300-£500 per annum.

An additional option is being demonstrated on one of the show homes, which could further reduce or even eliminate these bills. The tiled roof has been replaced with an entire photovoltaic ‘terracotta’ roof, along with part of the facade. This will generate enough energy to meet most of the home’s energy and heating needs.

For Stephen Wittkopf, Managing Director of Üserhuus AG, the future of architectural design lies with the integration of renewable energy technologies. 'This first-in-the-UK integrated, terracotta-style cladding and roofing PV system paves the way for future housing,' he says.

The Üserhuus/Tigh Grian concept has already been commissioned for use on a 50-unit housing development in Alva, a town in the central lowlands of Scotland, with construction due to start this year.

Dr David Kelly is a Group Director at BRE

Further information

• Images © BRE
• This feature is taken from the RICS Building control journal (February/March 2016)