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Avante, Coxheath, Maidstone, Kent

24/11/2009

Crest Nicholson's competition winning homes combine design quality, modern methods of construction and sustainability.

Crest Nicholson's Avante is a mixed tenure housing scheme of apartments and houses being developed on the former Linton hospital site in Coxheath, Maidstone. As a winner of a government-backed innovation competition, the homes are a testbed for leaner, greener building.

Description

Remember the government's Design for Manufacture competition? Think back to 2005 and the heady days of the housing boom when then deputy prime minister John Prescott set a challenge to create sustainable, well designed, good quality homes cost effectively. The Avante scheme has its roots in the competition, which was organised by the Homes and Communities Agency (then English Partnerships).

The SixtyK house generated by the consortium of the same name for that competition was one of the winning designs and has since formed the basis for larger-scale developments in Newport Pagnall and here in Coxheath. The consortium comprised Crest Nicholson, Kingspan Century, architect Sheppard Robson, Arup, Davis Langdon and MacFarlane Wilder. The 150 homes under development on the former Linton Hospital site are faithful to Sheppard Robson's competition-winning concept. Crest Nicholson is also using the scheme as a learning opportunity in more environmentally efficient housebuilding, most notably by participating in a field trial of Wrap's Net Waste Method. All homes are rated Excellent under the EcoHomes rating system, having been conceived before the Code for Sustainable Homes came into being.

Units range in size from one bedroom apartments to four bedroom houses. There are approximately seven housetypes, but they come in four variants depending on the position of the sun so that solar gain can be maximised. The homes are constructed using Kingspan Tek structural insulated panels (SIPs) with a brick and block skin.

Homes have some Lifetime design elements, including: a floor gulley in the downstairs cloakroom to allow a walk in shower to be installed, a knock-out panel in the first floor to allow a lift to be fitted, and a fuse spur on the stairs to allow for a chair lift.

The housebuilder has so far developed 114 homes on the site.

Key features

• Construction waste is being minimised by working with suppliers, buying pallets and re-using them, and using packaging of some items such as kitchens as site protection. The field trial of the Wrap Net Waste Method highlighted opportunities to minimise the cost of waste and avoid landfill. The housebuilder has also worked with BRE on waste monitoring.
• Homes are designed to maximise natural daylighting and minimise excess solar gain/heat loss where appropriate. Homes incorporate a central lantern to allow daylight into the centre of the home. This has aluminium fixed louvres to provide some solar shading. Windows are larger in living areas where more daylighting is needed and smaller in bedrooms
• Appliances provided by the housebuilder are triple-A rated.
• Homes have mechanical ventilation heat recovery (MVHR). The filter needs to be cleaned by the home occupant using a vacuum cleaner every week or so, and needs to be changed every five years, which can be easily done by the occupant.
• Homebuyers have access to an online user guide, via a password.
• Homes are designed for 105 litre water use per person per day (level 3 of the Code for Sustainable Homes).
• First homes sold in 2008 had 75 per cent low energy lighting. That figure has now been increased to 100 per cent.
• Utility usage in homes is being recorded prior to handover. Site staff check all meters on installation, quarterly and on the handover of a home.

Project outcomes to date

• Anecdotal evidence from purchasers suggests savings in energy bills are in the region of 25 per cent. The housebuilder is planning post occupancy evaluation to verify this.
• Carbon emissions savings range from 10 per cent to 22 per cent for the 70 homes completed in the 2008 financial year. These figures are based on the SAP 2006 dwelling emission rate percentage improvement over targets, compared to the 25 per cent improvement required for Code 3.
• Recording of utility usage has given the housebuilder accurate bills and avoided the estimated utilities bills usually received on sites in development.

Learning points

• Crest Nicholson group sustainability executive Dr Elizabeth Ness says: "Carbon emissions are not in recession and the government's climate change policy commitments mean that the 2016 legislative goal of zero carbon for new homes remains firmly in place. As a sector we have to innovate and, with our supply chains, find ways of responding cost-effectively. One thing we do know: at the moment our customers do not wish to pay more for sustainability features."
• Expanding on the last point, Ness continues: "The challenge we have as a sector is that, at present, customers do not place significant value on sustainability features of new homes, and neither do mortgage valuations. Both the sector, and the government, must place greater priority on clearly communicating the sustainability benefits to homeowners in everyday language, not in the technical jargon of SAP or Code ratings."

Sources and links

www.wrap.org.uk the Wrap website contains a full case study on the field trial of the Net Waste Method.

www.crestnicholson.com to find out more about the housebuilder, and read a case study about the SixtyK house.

www.designformanufacture.info read the background to the competition.