Newly built zero-carbon homes will be exempt from stamp duty from April for at least three years, Gordon Brown announced.

The problem for the growing number of ethical consumers is that there is no carbon-zero home in Britain at present and the handful of carbon-neutral developments in existence have run into teething problems. It may be years before there are sufficient carbon-free homes to have any impact on tackling climate change.

The move is intended to give impetus to investment into zero-carbon communities — 27 per cent of carbon emissions in Britain come from homes — and it is intended that no new home built after 2016 will contribute to climate change.

Owners of these homes will also save on heat and power in the longer term. This encouragement to new eco-home buyers will be formalised in the spring Budget and will be set out in the Finance Bill.

The stamp duty exemption was largely seen as a gimmick by green campaigners and senior figures in the property world. Many were hoping there would be financial incentives for all homeowners to adopt energy efficient heat and power systems.

David Stubbs, senior economist at the Royal Institute for Chartered Surveyors, described the time-limited stamp duty exemption as “a limited ambition at best” and “a pitiful attempt” to convince the public the Government was committed to tackling climate change.

“New build accounts for 0.8 per cent of the housing stock; this is a pittance compared with the existing stock of 25 million properties, which mostly remain carbon-inefficient. What does Gordon Brown intend to do about that?” Mr Stubbs said. “Until the Government stops making these pitiful attempts to convince the public that it is committed to tackling climate change, we will never reach our targets to reduce C02 emissions.”

Michael Gove, Conservative housing spokesman, said that it was worth supporting tax changes to enourage environmentally friendly behaviour, but added: “I fear that there is less to this than meets the eye. The news that the Chancellor kept hidden that this tax incentive will only last for a few years suggests it’s more about renovating his reputation than laying solid foundations for a carbon-conscious future.”

Developers are also unclear what the Government means by a carbon-free home and are worried there could be too many proscribed building materials. The industry has asked for a formal definition.

Angus McIntosh, head of research at property consultancy King Sturge, said: “The concept of zero-carbon homes is just soundbite politics. New homes account for only 1 per cent of overall buildings so will have a negligible effect on emissions. There may be carbon spent creating the building materials. There may be carbon spent getting to and from the home.”

It was unclear how the Government intended to measure energy consumption — whether it would be of the buildings, the occupants or the construction of the building, Mr McIntosh said. “A badly insulated four-bedroom home occupied by six people is, per person, more efficient that a well-insulated four-bedroom home where only one person lives,” he said.

The Home Builders Federation accepted that the stamp duty exemption was a good start, as long as it was not too short-lived. David Mitchell, its technology director, said: “The Government must realise there is no one-size-fits-all model for a carbon-zero home. We want a definition of a carbon-zero home that gives us flexibility and we also need some proper accreditation for new green inventions to ensure they work and are proven energy efficient.” The Energy Saving Trust welcomed the move but said there were no zero-carbon homes in Britain and did not envisage one until 2030. Its definition of a zero-carbon home is one that generates its energy from the dwelling, whether by solar panels or biomass boilers. Some campaign groups define a home as zero-carbon if it is run by electricity sourced from a wind farm.

Paul King, director of campaigns at WWF, said that it had lobbied for green homes for four years and said the stamp duty exemption was “a great breakthrough”.

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