Eco homes: the rise of "carbon appeal" "Carbon appeal" rather than "kerb appeal" is being pushed now. The Energy Saving Trust finds that 53 per cent of buyers are willing to pay up to £3,350 more for green features. But volume house builders are slow off the mark. Barratt is leading the way, building 185 zero-carbon homes with Kingspan Potton, using ideas developed by the Building Research Establishment at Hanham Hall just outside Bristol. They should be finished in 2015 and save 60 per cent on the carbon footprint of residents without requiring them to change their lifestyles. A four-bedroom home can be bought for £279,995 to £306,995 (0844 811 1855; barratthomes.co.uk/hanhamhall). Self-builders have been more energy-aware for years. Kingspan Potton produced the first zero-carbon house in Britain in 2007. Called The Lighthouse, it was clad in sweet chestnut, shaped like a spinnaker and could run on £31 a year. This has now been dismantled but provided great inspiration for change. Some of the most exciting work is being done by individuals like Richard Hawkes, who developed another prototype zero-carbon house called Crossway, near Staplehurst in Kent. It was shown on Grand Designs in 2009 and caught viewers" imagination. Richard, an architect, worked with the help of engineer Michael Ramage, based at Cambridge University's Department of Architecture. "We spent £335,000 on the site and around £445,000 on the house," he says. After landscaping, it is probably closer to £550,000. They went for a cave shape, a highly insulated envelope. The Hawkes family inside their low carbon home (PHILIP HOLLIS) We peeled the land up to make an arch, then used tiles made from the land instead of bricks, and covered it in soil and flora. We have no radiators or underfloor heating. A heat recovery ventilation system and a thermal store supply extra heat in winter. They installed the first UK combined power and heat solar panel and use a small biomass boiler when winter bites. How is it working, three years on? Richard and his wife, Sophie, now have two children - Oscar, four, and Verity, two - and have just bought a little more land so that they can keep pigs, plant more fruit trees and increase their biodiversity. Richard measures energy use all the time and estimates that annual cost is £1,057 but annual income (from the grid and Good Energy) is £1,067, so their net gain is around £10. The feed-in tariff rates keep changing, but in future we could be net gainers by over £2,000. The Chinese are beating a path to his door to find out how it is done. Low-carbon homes for sale London: Olympic Mews, Wandsworth, is being built by boutique engineer enthusiast turned developer ConceptM as a series of round timber eco homes in the garden of a large period house. Prices start at £930,000 for three bedrooms, through Knight Frank (020 7861 5499). 2 Your chosen plot: The Wickhambrook is Potton's new barn-style, four-bedroom house for self-builders which offers 50 per cent lower running costs, or an annual energy bill of around £450. Build price, not including the plot, is an average £291,000 (buildapottonbarn.co.uk or phone 01767 676400 to speak with an expert at the showcase centre). 3 Cambridge: a Code 4 four-bedroom house on Seven Acres new development by Skanska. Price £745,000 through Savills (01223 347000). Worcester: at Woodside Gardens, Lark Hill Road, houses by ZeroC are cut into an earth bank, use air exhaust heat pumps, underfloor heating, special solar shading and super insulation. Knight Frank (0121 200 2220) is selling with prices starting at £199,500 for a one-bedroom home.