A row has erupted between Britain’s £700 billion commercial property industry and Ken Livingstone, the Mayor of London, over how the capital’s office buildings can be made more environmentally friendly.

Mr Livingstone wants the industry to ensure that 20 per cent of the energy used to run new buildings in the capital comes from renewable sources from 2008 – double the current 10 per cent guideline.

However the British Council of Offices (BCO), the property industry’s trade body, claims the proposals are doomed to failure as the 10 per cent target is regularly being missed.

The BCO, whose members take in developers, architects and many of the country’s biggest office tenants, such as large banks and major law firms, claims that many of the new buildings planned will fail to make the grade.

The row has become public because a review of the renewable energy proposals began yesterday, giving all parties the final chance to lobby for changes to Mr Livingstone’s plan.

The debate centres on his wish for buildings to generate their own power through solar, wind and other renewables, and the developers’ preferred plans to reduce energy usage.

Developers insist that energy savings on new offices will be better achieved by efficient design, sharing excess heat with residential developments and increased use of automated systems to turn off lights and computers when not in use. They claim that wind turbines and solar panels are highly inefficient in the capital.

Richard Kauntze, chief executive of the BCO, said: “At present we have a situation where on-site renewables are meant to account for 10 per cent of buildings’ total energy requirement. However, the BCO is sceptical about whether 10 per cent is actually being achieved. Anyone trying to install photovoltaics [solar] in a built-up area will know that reaching 10 per cent is extremely tough and a figure of up to 7 per cent is probably what is being achieved.”

The use of wood chippings for firing boilers risks huge carbon emissions transporting them into the City, the property industry claims.

Peter Rogers, chairman of Stanhope, the construction company, and founder of the UK Green Building Council, told The Times: “Twenty per cent is a nonsense. There is too much gamesmanship and not enough common sense. Renewables tend to work outside London, but not in.

“At the moment the GLA [Greater London Authority] is spending too much time dumping on the developer and not enabling energy saving to happen. Getting the infrastructure right for future fuels is important. We need local power generation. Offices do not need heat. They create heat. Local authorities need to put the pipes in to take that for hot water in nearby residential.”

Foreman Roberts, the engineers, calculated for the BCO that an 11-storey building in Central London covering 22,750 sq m and costing £66.5 million would have to spend £2.6 million to meet the 20 per cent renewables target – 3.9 per cent of total project cost – up from the £1.6 million extra cost to meet the 10 per cent renewables guideline.

The GLA declined to comment.

The powerful alternatives

— Building owners and tenants looking to make a 20 per cent carbon saving from their energy usage have more than solar, wind and biomass power to turn to

— “Power factor correction” is the jargon for ensuring that the hot air expelled from air conditioning systems is used to reheat parts of the building that need it

— Thermal mass is a system used by the Victorians that works today for brick-based buildings. Heat built up on outer walls in the day is retained at night in thermal storage heaters

— Chilled beams or ceilings rely on water running along metal plates between floors. This can replace conventional air conditioning

— “Mixed mode operation” is the jargon for keeping doors and windows open whenever air conditioning is not needed

— Ice storage uses cheap nighttime electricity to make a massive ice block in the basement for cooling a building during the day

— “Switch off and save”, the 1970s addage, holds true. Turning off unused computers and lights cuts power use and keeps temperatures down

London's latest “Greenscraper”

The Willis Building, 51 Lime Street

Owner: British Land
Developer: Stanhope and British Land
Size: 29 floors, 520,00 sq ft lettable space
Main tenant: Willis, with 465,000 sq ft

— Beats building regulations requirements for fuel and power conservation by 20 per cent, helped by automatic light sensors and low-energy lightbulbs

— Automatic taps, individual flush sensors, reduced flush, leak detection and rainwater irrigation bring water consumption 30 per cent below average

— Construction waste cut by 30 per cent

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