Thirty year old Salford homes make case for passive design
Energy efficient homes of 1980s are 25 per cent better than 2013 regs.A group of 30-year-old terraced homes in Salford have been found to be 40 per cent more energy efficient than 2010 building regulations, and 25 per cent more efficient than anticipated 2013 regulations require. The 200 prototype houses designed to provide economic, low energy housing suitable for low income urban tenants were constructed using a design developed by the University of Salford in the mid-1970s.
The Salford houses continue to outperform most other UK homes because they were built with a high thermal capacity internal structure, protected by a highly insulated well-sealed envelope. This produces a ‘tea cosy' effect that maintains constant equable temperatures with controllable ventilation.
This high thermal and near air-tight method of construction, designed more than a decade before the Passivhaus standard was conceived in Germany, is achieved through the use of dense concrete block inner walls and floors of suspended concrete blocks, together with a thermal insulation thickness of 200mm around the entire structure. The result is an internal mass and thermal capacity about four times traditional values.
The large thermal capacity reduces temperature fluctuations and permits flexible heating strategies. This is in marked contrast to timber-framed constructions which can have a thermal capacity of around one quarter of traditional values, and suffer large temperature fluctuations.
A research paper, called The Salford low-energy house: learning from our past, outlines how staff from the university's Energy Hub revisited the experimental houses last year and examined their ongoing performance, gathering data on energy use and interviewing residents. They found that the 30 year old Salford houses still uses 75 per cent less energy than the UK average for space heating and that they are 50 per cent more efficient in energy use. In addition The Salford houses only require heating for three to four months of the year, against a UK average of seven months.
University of Salford's Dr Phillip Brown, part of the Energy Hub research team, said: "There is little difference in cost between traditionally thermally inefficient build and the relatively simple Salford house low-energy design. With many housebuilders currently worried that new homes are going to be much more expensive to build in order to meet the government's ambitious targets, the Salford model shows that this need not be the case. The Salford House cost just 7 per cent more to construct than identical neighboring properties, and yet saves 50 per cent on energy costs every year."
The research paper highlights the resonance of this project today, noting: "We are now in the midst of a decade of rapid change driven by the concerns of climate change and the requirements placed upon the UK by EU legislation. In the 1970s Salford City Council responded locally in a socially just and innovative manner to the urgent needs of their tenants. This led to the development of housing which was decades ahead of its time. Thirty years on it is, once again, urgent necessity that is the driver for EU, national and local action."
The research paper is available on University of Salford's housing and urban studies unit.