Home is where the Heat is...
George Pickard, FCIOB, of the Precast Flooring Federation gives a timely reminder
“Failure to build to the Salford standard will impose a massive unnecessary burden on national energy resources that will be carried forward well into the next century.” So said Report No. ED 179/59 published by the Energy Efficiency Office in 1987 on pioneering energy-saving house building in Salford. Yet 35 years later, this ‘Salford standard’ has gone largely unseen and unused, and it has taken a new report – The Salford low-energy house: learning from our past – to reveal the opportunities that are still being largely overlooked.
With the industry busy working towards the near-zero-carbon demands of the forthcoming Code for sustainable homes, the rediscovery of this pioneering work carried out in 1976 has surprised many. The brainchild of Dr J E Randell at The University of Salford, and J M A Hoyle, an architect with Salford City Council, the revolutionary houses have since been shown to require an energy consumption about 25% of that of the general UK housing stock and less than 60% of current Building Regulations.
Central to their design is a high thermal capacity internal structure protected by an insulated, well-sealed envelope. The high thermal mass is provided by constructing internal walls of dense concrete blocks with beam-and-block suspended concrete floors. The result is a thermal capacity about four times the norm, enabling maximum use to be made of incidental gains, reducing temperature fluctuations and permitting a range of heating strategies. This contrasts with lightweight houses, such as most timber-framed structures, that can have a thermal capacity around a quarter of traditional values and so can suffer large temperature variations.
Initially, the Council built a pair of two-bedroom semi-detached houses, followed by a prototype terrace of four houses and two flats. After detailed monitoring, they went on to build a further 200 or so dwellings. Unfortunately, changes to housing policy in the 1980s brought the number of homes built by local authorities to an effective stop and so the City Council built no more. But elsewhere in Salford, a private builder adopted the design for a small estate of about 50 flats and houses and a local housing association incorporated the principles in a sheltered housing development.
Thirty-six years later, it seems strange that the Salford experience did not become widely known and was not implemented to any extent by the private sector even though the excellent performance was publicised by a 1987 report and an article in Building Services and Environmental Engineer in 1979. A possible explanation for this can be found in the anecdotal evidence from contemporary private developers that it was difficult to sell the houses without central heating installed, as potential buyers considered that they lacked an essential amenity.
With these timely reminders from Salford, house builders are reassessing designs. At the same time, the Precast Flooring Federation is renewing its drive to expand the use of precast concrete flooring to all levels of the house-building industry. Combined with blockwork internal partitions, precast flooring adds to the thermal mass along with the additional benefit of excellent acoustic performance.