Where there’s a will
Can traditional new-build housing ever achieve high-level sustainability? Woking Council certainly thinks so and won’t let ageing planning consent get in the way of its grand designs
What reinventing a mothballed development of conventional homes as a code level five exemplar
Where Knaphill, Surrey
Who Woking Borough Homes and William Lacey Group
How long 18 months
Funding Combination of shared capital, loan and grant - Woking Council set up Woking Borough Homes in 2005 as its housing delivery company.
Richard Bell is getting used to hearing the words ‘surely that’s not possible’.
In 2008 Woking Council briefed Mr Bell’s employer, William Lacey Group, to transform plans for a 10-home development granted planning permission in 2004 - three years before there was any such thing as a code for sustainable homes - into a level five reality. The Brookwood Farm scheme is due for completion by early May. And, says chief architect Mr Bell, the design-build development will live up to its eco-billing. ‘A lot of people say, “well, they look like traditional houses - surely that’s not possible because to achieve code level five, you have to start from scratch”.’ Time to think again.
The completed homes will boast all the green technologies you’d expect from properties so high up the eco-ladder. Quite an achievement for a scheme constrained by ageing planning consent. So how did they do it?
‘We weren’t able to alter the basic proposals of the scheme, like orientation or height,’ explains Mr Bell, adding that a particularly tricky aspect was finding adequate roof area to put the power-generating photovoltaics. ‘But we managed to make it work.’
The learning curve is set to continue once tenants arrive in spring. Along with the University of Surrey, the council’s energy arm, Thameswey Energy, will monitor residents’ use of power and water, via the authority’s private wire system, which among other things will channel power to the homes from the authority’s CHP facility in Woking.
The data will be compared with energy and water use in some of the council’s other properties, including those built in the 1980s and, more recently, to building regulation standards.
‘This scheme shows that you can take a project or development and make it a response to its environment,’ reckons Mr Bell. ‘This project has been all about taking traditional housing and showing that the aim of reaching code level five is achievable in practice.’
In figures:
Windows - Triple glazed.
Power - ‘Sundog’ grid-connected photovoltaic panels. The homes will connect to council-owned Thameswey Energy’s private wire electricity system.
Heating - The five-beds boast hot water heating by solar thermal tiles. Location and space limitations made combined heat and power and ground-source heat pumps a no-go. Heat recovery from hot air leaving the house.
Water - Rainwater is harvested for practical use within the house, saving on mains water. The water can be used for water closet flushing and clothes washing.
External walls - Hitting code level five requires a low-leakage, high-insulation envelope. The homes feature insulated concrete form structural walling. Created by ICF Tech, the system is based on a 25mm module. A ‘green’ concrete mix was also developed for the structural element, specially designed to flow to eradicate voids. This method’s practical advantages include little or no loss of progress during wet or cold weather. Very low U values are achievable and it produces excellent levels of sound insulation.
An excellent aspect of the PV System - The Sundog Energy / Nu-lok solar slates seamlessly integrate with the natural slate roof finish, creating an attractive uniform appearance. This system enables the available roof area to be utilised to the full because the solar slates can be coursed close against hips and valleys.
U-values:
Ground Floor: 0.13
Walls: 0.11 & 0.15
Roof: 0.1
Windows: 0.8
External Doors: 1.0
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