Building type Affordable Housing
Building age post 2000
Location Elmswell
Cost of work £ 4,390,000
District Mid Suffolk
Features Green Sedum Roof,Natural Materials,Rainwater Harvesting,Insulation and Glazing,Waste and Recycling

Clay Field is a development of affordable housing in the village of Elmswell.  A partnership between Suffolk Preservation Society, Mid Suffolk District Council, Orwell Housing Association and Elmswell Parish Council and built by local contractor Seamans Building.  The scheme was the result of a RIBA design competition and achieves Eco Homes Excellent rating.

The concept was to provide exemplar affordable homes which were designed to be energy efficient and sustainable, have a high design quality and provide positive public and private spaces.

Sustainability Features

Hemcrete Sprayed Insulation

An insulation material that can be sprayed or cast insitu to create a monolithic walling system.  Hemcrete is inherently air tight, has high thermal mass, good insulation values, is breathable, assists acoustics and is sustainable.  The material is not load bearing and is usually used in conjunction with a timber or steel frame.

Hemcrete’s properties are:-

Carbon Capture                    130 kg CO²/M³

Thermal Conductivity          ? = 0.06W/m.k

Density                                   275 kg/m³

Air permeability                     0.75 gm/m²/mm/hg

Air tightness                          <2m³/m².hr @ 50 pa

 Product cost                          approximately £135 per m³ (supply only)

Biomass Boiler

The heating system for all 26 dwellings is centred around a biomass fuel district heating system using a Twin Heat CS150i automatic biofuel boiler with a nominal 150 – 180 kw output, fuelled by wood pellets.  Heat is distributed around the district heating pipework which contains in total, approximately 3,500L of water.  The flow temperature is approximately 80ºC with a return temperature of approximately 60ºC.  Heat exchangers are positioned in each dwelling to control and distribute heating and hot water to the property and metering facilities allow the monitoring of fuel consumption to each dwelling remotely.

The installed cost of the district heating scheme was approximately £230,000.00 and a grant of £100,000.00 was received towards this from the Carbon Trust.

Whole House Ventilation

A heat recovery unit, located integrally within the cooker hood in the kitchen supplies fresh filtered air to the Living Room and Bedrooms and extracts stale air from the Bathroom and Kitchen via a network of ducts concealed within the properties.

The system is designed to change all air within the property at least once every two hours.

Rainwater Harvesting

Each block of dwellings, containing two terraces were supplied with a Rainsava 6,500L underground rainwater harvesting tank, giving a total storage capacity on site of 26,000L.

A vortex filter, installed in the pipework before the tank, removes leaves and debris.  A sump pump within the holding tank distributes the filtered water to header tanks within each house, via pressurisation units located within the landlords sheds.  Header tanks incorporate a mains cold water top up facility to prevent the tanks emptying when there is a lack of rainwater supply.

The header tank distributes recycled rainwater to WC’s throughout each house, as well as supplying non-concussive external garden taps.

The rainwater harvesting system serving the whole site had an installation cost of approximately £63,000.00.


The Kitchen provider chosen for the scheme was Chamois Furnishings Limited.  Their kitchen ranges are made from 85 – 100% recycled timber panels and the remaining timber content is FSC Certified.

The Liberti range chosen was the premics product within the affordable Kitchen collection.  Whilst the Kitchens are generous in size and well fitted out with units, the supply only cost to each property was retained within the £1,500.00 budget set at tender.

Cedar Shingle Roofs

To maintain the sustainable aspects of the scheme, an early decision was made to use cedar shingles on the sloping roofs.

The roof covering at Clay Field is therefore from a renewable resource and is recyclable, as well as offering carbon captive and reduced building loads.

Other Incorporated Features.

Rainwater Disposal. – No rainwater is removed from site via drainage, and in order to avoid soakaways in the clay soil, careful contouring of the adjacent meadow to form swales allows water to gradually permeate into the ground assisted by the many trees planted on the site.

Lime Renders –  The gable ends of the buildings are lime rendered directly onto the sprayed hemcrete, to create an air permeable structure which offers resilience, using a recyclable product.

Earth block garden walls – The perimeter walls to gardens are constructed from earth blocks above damp proof course level, and are rendered with lime render and capped with a cedar shingle coping.

Sedum Roofs to stores – A high performance single layer felt provides waterproofing to the flat roofed store areas, and is overlaid with insulation, deck, protection fleece, drainage layer, substrate and sedum planting to provide a green roof.  The roofing cost inclusive of trims etc equates to approximately £110/m2.


Design Process

We were trying to achieve a healthy living environment, providing homes with minimal embodied energy and running costs using carbon neutral energy sources, and to integrate sustainable materials to greatly reduce the carbon footprint.

The motivation was to show that affordable housing could be of a high quality design and specification and to be an exemplary in sustainable housing at a reasonable cost.

Planning requirements were met by keeping the height of the buildings as low as possible resulting in sunken lounges in the 3 bed houses.  The planning authority was very supportive and embraced the innovation and design concepts.



£100,000 was received from the Carbon Trust towards the biomass boiler.


Green Lifestyle

We worked with our tenants and leaseholders before they moved in to provide them with information about the concept of the scheme and how it would implicate on the way they were to live in the properties.

We are continuing to work with them to provide individual tailored advice on how they can maximise the efficiency of their homes.  This has been possible with the continued support of our Sustainability Consultants, Burro Happold, who have been monitoring the energy use, water use and co2 emissions.

Out side the living spaces, provision has been made for recreation, with a wildlife meadow, open planted areas, a football pitch and children’s play area contained within an orchard. There are also composting facilities on site together with a number of allotments, from which residents can produce their own vegetables.

We believe that the awareness and understanding of sustainability issues of our tenants and leaseholders at Clay Field is greater than that elsewhere and understand that some have embraced greener living beyond the building they occupy.



The properties provide warm, light and spacious homes with lower than average running costs, benefiting from solar gain in colder weather and able to be easily ventilated during summer.  Overall, we are very pleased with the outcome and consider that we’ve provided an exemplar sustainable, near carbon neutral, affordable housing scheme.

The design of the units and the open space, the construction using hemp and the whole house ventilation system are particularly successful.  If we were to start the project again we would consider not using the biomass boiler as the scheme is too small for it to be as economical as it can be.  However, the biomass boiler contributes massively to the carbon savings of the scheme.

The rainwater harvesting system, once integrated into the design and installed, is an unobtrusive and easily maintained system, which provides a direct saving to the occupiers.


Suppliers and Professional Services Used

Architect – Riches Hawley Mikhail Architects

Main Contractor – O. Seaman & Son Ltd

Sustainability Consultant – Burro Happold

Quantity Surveyor – Hyams

Structural Engineer – BTA
Civil Engineer – Cameron Taylor

Landscape Architect – J&L Gibbons



Won:   Housing Design Project Awards 2006

Housing Design Futureproof Award 2009

RIBA Award 2009

Suffolk, Creating the Greenest  County Sustainability Award

High Commended:    RICS Sustainability Award 2009

Shortlisted:    Inside Housing Sustainability Award 2008

Local Authority Building Control Sustainability Award 2009

Local Authority Building Control Large Housing Scheme Award 2009

                            Grand Designs Award 2009

Achieved:       Midlist (last 20 schemes in country) for the Sterling Prize