When it comes to building a carbon-neutral home, wind turbines don’t work, so far, but bore holes and solar panels do.

That is the conclusion that can be drawn from the first detailed working trials by the University of Manchester of energy-saving devices used on the next generation of carbon-friendly homes built by Barratt Developments, one of Britain’s largest housebuilders.

Bore holes and solar panels would take, respectively, 15 years and 37½ years to pay for themselves, based on today's electricity prices.

Nonetheless, for a relatively small capital cost, the savings these devices make to the environment and the added value they put on the price of a new home are likely to make them attractive to the housing industry.

Housebuilders are under pressure to meet a government deadline to make all new homes carbon-neutral by 2016.

They also face increased pressure to prove their green credentials in competitive bids for government-owned land, where tracts of land for thousands of homes at a time can come up for auction.

The findings will also be of interest to the growing numbers of eco-conscious homeowners, epitomised by David Cameron, the Tory leader who hit the headlines with his installation of wind turbines and other energy-saving devices in his Notting Hill home. Purchases of carbon-neutral homes will attract zero levels of stamp duty under new government proposals.

Barratt last year built a group of empty homes in its “eco-village” of Chorley, Lancashire, complete with green technologies ranging from wind turbines and ground source heat pumps to solar panels for general electricity or warming hot water tanks.

Mark Clare, group chief executive of Barratt, said: "The eco-village has been an invaluable test bed, which has helped separate renewable myth from renewable reality. The challenge now is to drive down costs to ensure that they have the widest possible take-up."

After 15 months of initial trials of the Barratt homes, a ground source heat pump was found to have “worked very well”.

Extracting the earth’s natural heat from a 30-metre hole reduced carbon dioxide emissions in typical homes by 62 per cent each year. The use of a ground source heat pump, costing £7,800, generated 2.6 times the heat it used to work.

Tony Sung, a lecturer in civil engineering at the University of Manchester who oversaw the trials, said: “ At 30 metres, the earth emits a constant temperature of 10 degrees to 12 degrees centigrate. It is effectively both a landfill for energy from the sun and emanating heat from magma (molten rock) deep down.”

Solar panels, known in the industry as photovoltaic (PV) roof panels, were also found to have “worked very well”.

An unobstructed PV system — free of leaves or other detritus — generated 850 kilowatt-hours a year. They typically cost £4,500.

But the results from micro wind turbines — either 1 metre and 1.7 metres wide — were “disappointing”. In Britain’s windswept North West, the turbines turned but there was too little AC electricity produced even to calculate how long it would take for the devices to pay for themselves.

Dr Sung said: “We do believe the turbines generate an initial form of energy in terms of DC to give a smooth output but for one reason or other could not measure AC output. We can only say the onsite experience was disappointing. There is DC power and AC output but below what was anticipated from the wind resources. It is about the conversion.”

Barratt is weeks away from knowing whether it will be chosen as a preferred bidder to build the country’s first eco-village on 6.1 acres of land being sold off by English Partnerships, the Government’s national regeneration agency. This is sufficient space for 150 homes.

Barratt was shortlisted, The Times revealed earlier this year, alongside rivals including Taylor Wimpey, Edward Ware, Gleeson Homes, Places for People, Artisan H and Urban Splash.

English Partnerships wants the eventual winner to build super-energy-efficient houses about six years ahead of the Government's deadline for ensuring that all new housing is carbon-neutral.

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