If the Waltons were around in today's Green-conscious age, they would probably live in a house like this.

The five-bedroom eco property in Lewes was purpose-built for a family of seven to have minimal impact on the environment.

Last year it won an award for being the greenest self-built home in the UK.

Property owners Aaron and Raphaella Curtis bought a piece of scrubland for just £60,000 and constructed a four-storey building with solar panels, extra insulation, double glazing and a low-carbon footprint.

Others had rejected the brownfield site, next to a partially demolished viaduct, but the Curtis family saw the potential. They used local craftsmen and materials and spent £240,000 on construction.

For the next few years it became their family home. Now the couple are selling the house in Pinwell Road, Lewes, for £865,000.

Mr Curtis, 44, said that with five children, there was little choice but to build their own place.

He said: "We couldn't afford to buy a house like that. We could just about afford to build one.

"We designed it in a way that fits all our needs.

"It has got low running costs, it doesn't take much to heat."

In 2006, the home claimed the RIBA Ibstock Downland Prize for Sustainability and was named Norwich and Peterborough Building Society Eco house of the year.

The house was designed to make the best use of a compact amount of space. During the building process, travelling distances for materials were cut down to the minimum with as few deliveries as possible.

The plans were drawn up by BBM Sustainable Design, of Lewes.

There is underfloor heating powered by solar panels, a condensing gas boiler or, as a last resort, electricity.

Mr Curtis runs a property company but this was the first home he has built for his own family - wife Raphaella and their children Sorcha and Ozora, aged 14, Hasia, 11, Ryan, six and Alisha, four.

Mr Curtis said: "I think they have learned something from it. We showed them what it was going to be before it was built."

The family are moving to a Georgian terrace but have plans for other eco ventures in the future.

When asked why he opted for an eco-friendly design, Mr Curtis said: "Why not?"

He said: "This was a huge opportunity to undertake a unique project. We've created an environmentally-friendly and fun, living space on a brownfield site using local labour and materials.

"If you are building it from scratch, the difference to make it so-called green isn't that much, so why wouldn't you?"

See the eco house at www.lewesestates.co.uk under "country homes".

Norwich and Peterborough, which bills itself as a "green mortgage lender", is looking for entrants for its sixth annual eco self-build competition.

The prize is £5,000. The Government has announced that all new homes will have to be carbon neutral by 2016.

Latest figures show houses are responsible for producing 27 per cent of the UK's carbon dioxide emissions each year.

Eco homes are encouraged to be built on brownfield sites, have water recycling systems, super-efficient insulation and double glazing and energy-saving heating systems.

To enter the contest, visit a branch of Norwich and Peterborough or call 0845 300 2522.

Have you installed anything green-friendly like solar panels at your home? Have you transformed your home into a green palace? Tell us about it below.