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Park Dale
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The scheme was commissioned by Wakefield and District Housing (WDH) and half-funded by the Homes and Communities Agency (HCA). Regeneration specialists Keepmoat used Bramall Construction to build the two, three and four-bedroom homes.
Tom Hustler, communications manager at the HCA, says: “The Airedale estate was built between the wars to house coal miners and had the classic problem of under investment and all that brings. Wakefield and District Housing could have done the absolute minimum to maintain it but instead they decided to use a bit of imagination.”
It had been WDH’s long-term goal to build the UK’s biggest, zero-carbon, affordable housing scheme without commercial subsidy. It wanted to prove to the industry that eco-homes could be built on a large scale, and encourage other associations to do the same.
Crucial to WDH’s vision of the development was a commitment to the area and its resources. Local labour, skills and materials were central to the build. This method cut down on transporting workers and supplies to site and the carbon emissions generated by such activity.
Bramall Construction’s design and build coordinator, Ashley Jones, says: “Our client particularly wanted to keep the labour used local. Given our knowledge of this type of construction, and so we could keep the Wakefield pound in Wakefield, we decided on bricks and mortar.”
This traditional construction method was used to deliver inventive green solutions. “There are many ways to achieve zero carbon – be it through bricks and mortar, or timber framed or pre-fab,” says Jones. Bricks and mortar ensured costs were kept low, which was essential if the scheme was to succeed, and delivered high-quality airtightness of 3.0 at 50 Pascals and below.
Park Dale took one year to plan and for the teams to develop their Code for Sustainable Homes proposal. WDH, the HCA, Keepmoat and Bramall Construction then teamed up with design and management consultants NPS Group to complete the 91 homes in 84 weeks, almost exactly on schedule; the few days lost were due to harsh winters.
The groups’ initial plans continued to evolve due to the complexities of Code Level six. WDH community regeneration service director Helen Wordsworth explains: “Although it was frustrating at times, we were all working to the common goal of achieving Code six and it was inevitable that we would have to go into this level of planning to ensure we were successful.”
Jones explains the decision-making process behind the chosen eco-features. He says: “First, we wanted to maximise the thermal efficiency; then we focused on an airtightness of three, which was the minimum we felt happy dealing with. Finally we looked at renewables.”
Park Dale features triple-glazed windows. Bramall balanced the size of the windows and the amount of natural light let in with a heat loss parameter of 0.8. This, together with the brick and mortar construction, resulted in U-values being twice as good as Building Regulations require.
Heat is retained by a mechanical ventilation heat recovery system.The system uses a low-energy fan to feed fresh, filtered air, which has been pre-warmed by recovering heat from the stale, damp air from kitchens and bathrooms, into living areas.
Energy generation
Energy is generated by in-roof photovoltaic panels and a district biomass heating system run on locally-sourced wooden pellets, which delivers heating and hot water for the entire development via an underground pipe network. The photovoltaic requirement for individual plots was estimated by SAP calculations. In keeping with the relatively traditional look of the properties, WDH chose in-roof panels for a subtle appearance.
Smart meters are fitted in each residence to allow WDH to monitor energy usage and occupants to make improvements based on their new awareness.
Excess electricity generated is sold by WDH who use the funds raised to reinvest in renewable technologies for other existing properties. Wordsworth says: “We are committed to looking at ways in which new technologies can help reduce the cost of living for our tenants, and reduce fuel poverty, right across the district.”
Bramall’s Jones sounds a note of caution over energy-efficiency measures. He says: “When trying to achieve Code six, everybody focuses on energy consumption but it’s not just that – you have to use under 80 litres of water per person per day, then there are daylight factors in the living room, kitchen and home office to take into account.”
Waste water is dealt with in two ways. Greywater recycling fills the cistern of ground floor toilets with used, filtered bath and shower water. The site’s underlying sediment is made of porous limestone allowing soakaway drainage. The sediment’s permeability was tested prior to construction to confirm its percolation rate.
Three key questions were applied to each technology Keepmoat and WDH considered. Jones says: “It was a constant, iterative process – we asked: Does it work? Does it achieve Code six? How does it cost up?”
Heating demand is expected to be just 20% of the national average. Total energy bills are expected to be 40% less than a regular house and 25% less than a modern newbuild home.
Local regeneration
The development’s benefits are not limited to energy conservation and innovative technologies however. Wakefield and District Housing received the housing stock from the local council in 2005 and planned to ‘rejuvenate the estate physically, environmentally and socially.’ Park Dale is the culmination of their vision. HCA head of area Naz Parkar says: “These houses not only provide local tenants with homes they can afford but will help protect the environment for future generations.”
Local tradespeople as well as tenants have benefited from the scheme through learning new skills. More than 40 apprentices gained eco-construction experience during the build.
Parkar adds: “WDH’s scheme was very competitive as it cost the tax payer no more per unit than the baseline rate from other associates would. I was slightly cynical about whether it could be delivered but when I visited on its completion it was fantastic. We couldn’t be more satisfied.”
For further information visit keepmoatgreensolutions.co.uk
This article originally appeared in the March 2012 issue of Greenbuild. For a free subscription, click here.
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