30th March 2009 - Clay Field sets the Sustainability Standard
Clay Field in Suffolk is the work of London-based architects Riches, Hawley Mikhail, who won the commission in 2006 in an RIBA open competition comprising 26 affordable dwellings - 13 two-bedroom houses, nine three-bedroom houses and four one-bedroom flats. "It combines contemporary design, sustainable construction with low energy use and innovative local materials," say the architects.
The project has achieved 60% reduction of in-use and embodied carbon emissions compared to almost any other multi-unit residential project completed in the UK to date. What is surprising is that they have achieved this using essentially traditional technologies with the help of consultant Buro Happold.
The sustainability credentials are impressive: cedar-clad and lime-rendered exteriors conceal a carbon-negative structure of timber insulated with Hemcrete, a mixture of lime and hemp. Specially designed rooflights measuring up to 2m by 1.2m maximise passive solar gain and control ventilation, and heating and hot water is fuelled with locally-sourced wood-chip biomass emitting significantly less CO2 than localised gas boilers. In addition rainwater is collected in underground tanks with approximately 1,000 litres storage, and is used for flushing toilets and watering gardens.
Diagram- courtesy of Buro Happold
Rather than employing solar panels the houses are designed to work as solar collectors, and provide most heat and ventilation passively. Riches Hawley Mikhail achieved this by designing in a large south-facing array of rooflights and ensuring with the lay-out and cross-section that there was no over-shadowing. They placed the larger of the specially designed rooflights on 40% of the south facing elevations and the smaller ones on the north facing. By a series of arrangements to the standard block and its roofs, -including roof pitches of 780- each house enjoys uninterrupted winter sun. This improvement in daylighting arose from careful modelling of the building envelope and glazing ratios by Buro Happold to establish the optimum relationship between solar gain and daylight penetration. A further bonus is that all homes get a view - they do not look onto each other but onto open space.
Internally, the layout is designed to maximise space, light and through-ventilation. The floors are staggered with an open stairwell running from the kitchen to the rooflights allowing a through-flow of air, so the homes are ventilated naturally in the summer. In winter, an additional mechanical system removes 80 per cent of heat from outgoing air and uses it to heat incoming air.
Rooflights are frameless and flush with the cedar roof
The rooflights, which were painted pale green to match the windows also play an important role in the aesthetics of the scheme as the seven different sizes provide visual interest. However, as the level of the glass was designed to be in line with the cedar roofing the rooflights do not protrude. Also the glazing extends edge-to-edge showing virtually no framework. So, although the rooflights are large, they do not dominate the scheme.
Photographs by Nick Kane
Further links:
http://www.bdonline.co.uk
http://www.dezeen.com
http://www.building.co.uk