The developers are not aiming to create a cutting-edge eco-project in the mould of the Peabody Trust's Bedzed carbon-neutral project. Instead, they plan to create a house that uses half the energy of a conventional home, has water-saving features and is easy and economical to build.
The homes have been built by contractor Willmott Dixon's eastern housing division, using off-the-shelf products. Chiel Boonstra of DHV AIB, the Dutch environmental consultant working on the project, says: "The most important aspect of the project is being able to replicate it in the future. It's not overly complicated and is practical to build."
Tim Carpenter, the contractor's managing director, believes that time savings gained by using prefabricated building techniques, such as cassette wall units, could bring the their cost down to the same level as a conventionally built home.
Features include the use of timber frame construction, for its low embodied energy level. Insulation is heavily employed; the walls have a U-value of 0.25 W/m2°C and energy-efficient windows will be used to minimise heat loss. Sun rooms are included on south-facing properties to allow passive solar gain.
Boonstra points out that it is not always possible to orientate buildings in a southerly direction so properties with an east-west orientation are fitted with heat recovery systems to heat incoming air, rather than sunrooms, to minimise energy use.
Other green features include natural ventilation in some of the properties and solar collectors to heat water. Rainwater is collected and one of the homes will feature greywater recycling. This will be monitored to assess its worth as an investment for future projects.
The five house types are to be monitored for building cost and energy consumption and tenants will be quizzed on what they are like to live in as a guide to how to design similar future projects.
The ecopark project will be assessed against the Dutch "green finance" model. In the Netherlands, homes that meet this prescribed standard qualify for extra government funding, and Gallions housing division hopes the UK government will adopt the Dutch funding system. It is also hoped the homes will earn an "excellent" rating under the BRE Eco Homes assessment method.
Gallions plans to build an exhibition centre that will open for a year to spread information about the project. The housing association would like other developers and associations to learn from the project and build more environment-friendly houses.
On the next page we provide the details for some of the products that are likely to be used on the Gallions Ecopark scheme.
Energy efficient boiler
Eco Hometec will supply the ecopark with the wall-mounted EC 25 Compact condensing boiler, which employs a modulating fan, burner and pump to maximise energy efficiency. It is suitable for conventional and underfloor systems and features dual-flow temperatures. The boiler has an output of between 8 and 28 kW, and a variable control output device supplies it with less fuel as the external temperature rises. The boiler is claimed to be 86% efficient when connected to a conventional heating system and up to 98% efficient when used with the low return temperatures typical of underfloor heating systems.
Eco Hometec
www.eco-hometec.co.uk
Flexible underfloor heating system
Some of the houses on the scheme will be heated using Polypipe Building Products' Polyplumb underfloor system, which uses a standard polybutylene barrier pipe and associated push fit connectors. A special screeded floor panel is used in solid floor systems; this plastic panel features protrusions that are spaced to hold the pipe in position.
The concrete screed is then poured on top.
The pipe can be clipped to the sides of joists when used with a suspended floor system, or laid between battens above the joists. A dedicated manifold is required to connect the pipe to the rest of the heating system.
Polypipe Building Products
www.polyplumb.co.uk
Sustainably sourced windows
The project's fenestration is being supplied by Swedish Windows. The Scandinavian system uses laminated wooden frames made from sustainably sourced timber. Low-emission argon-filled double-glazing units with a claimed U-value of 1.1 W/m2°C measured in the centre of the glass will be used. A number of Swedish Windows' products are being used on the project, including sliding doors, windows, and the screens forming the sunrooms to increase passive solar gain.
Swedish Windows
www.swedishwindows.com
Adjustable monobloc mixer tap
Spray-type taps will be used on the project to minimise water usage. Pegler makes the Peglerspray lever-operated monobloc mixer tap suitable for rinsing hands. The spray outlet can be adjusted to suit the water pressure on site and is supplied with a flow straightener to help fill the washbasin. The tap, which comes in a chrome finish, is suitable for use with water pressures ranging from 0.2 to 10 bar.
Pegler
www.pegler.co.uk
Aluminium-framed tube solar collector
AES Solar Systems are supplying the Zen solar collector to heat water for the dwellings. It is made of a copper sheet and tube solar collector under a sheet of low-reflection glass in a black anodised aluminium frame. A flow rate of 0.5 litres a minute for every m2 is recommended and the flow and return pipes can be connected using standard 15 mm compression fittings. The unit can be fitted to the roof using a flashing kit.
AES Solar Systems
www.aessolar.co.uk
Long-lasting greywater recycler
Water Dynamics' greywater recycling system will be tested in one of the homes. The firm claims that it can achieve water savings of up to 40%. The grey water within a storage reservoir is filtered and disinfected using slow-dissolving bromide tablets that last up to a year. Up to 180 litres of water, enough for a day's toilet flushing, is stored in the system. Treated water is passed to a header tank that feeds the toilets; the system can automatically switch to mains water operation if the greywater supply runs out.
Water Dynamics
www.waterdynamics.co.uk
Credits
client (social housing) Gallions Housing Association client (flats for sale and visitor centre) Tilfen concept architect Splinter Architecton architect PRP Architects sustainable design consultant DHV AIB contractor Willmott Dixon Housing project manager PRP Project Services M&E Fulcrum Consulting
