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"There's a groundswell of interest in green issues right now," says André Chaszar, senior engineer at Buro Happold's New York office. "We first started hearing about them at time of the Rio summit in 1992. Even though the government didn't sign up to it, the public started to get a grasp of the issues."

Now consultants say corporate clients are beginning to show signs of interest in environment-friendly design. "Nike, Gap, Ford – they're all commissioning green buildings," says Chaszar. "Companies are going in for things like this to boost their image."

Buro Happold is working on a green headquarters for biotech firm Genzyme in Cambridge, Massachusetts. Designed by German architect Behnisch, Behnisch & Partner, the 29 500 m2 building will feature double facades, solar shading, a solar powered cooling system – and windows that can be opened. The technology would be unremarkable in Europe, but in the USA it's avant-garde stuff: most US office buildings are "sealed boxes" with power-hungry air-conditioning. "We think it's going to be one of the greenest buildings in America," says Renate Blauth of Behnisch.

Chaszar admits that Americans still view the movement as cranky. "Many people are very sceptical about it. The idea of opening buildings up instead of sealing them tight is alien to them."

Steve Keppler of the San Francisco-based US Green ºÃÉ«ÏÈÉúTV Council agrees that public concern is driving the agenda. "It's a grassroots movement and corporate America is catching on."

To nurture the tentative green movement, the USGBC has created the USA's first rating scheme for green buildings. The Leadership in Energy and Environmental Design package, which was launched in March, includes a toolkit for designing and constructing green buildings, and a certification scheme to grade the end product. Although still in its infancy, LEED has already been adopted by the city of Seattle, where all future buildings must comply. The biggest coup has been getting the federal government's giant General Services Agency to adopt LEED for all its future buildings.

It’s a grassroots movement and corporate America is catching on

Steve Keppler US Green ºÃÉ«ÏÈÉúTV Council

Only 40 private buildings have signed up to LEED so far, but the USGBC is busy gathering evidence in hopes of encouraging more. "We're taking a market-driven approach," says Keppler. "We're identifying specifically economic reasons for why it's worth doing."

Earlier this year, New York State introduced a pioneering scheme of tax credits to encourage more sustainable buildings. Under the $25m (£17.4m) scheme, building owners can offset a percentage of the cost of green construction against their tax bill. To qualify for aid, buildings must satisfy a range of criteria including reduced energy use, high internal air quality and waste recycling. In return, owners can claim back up to 1% of building costs over the first five years, plus up to 6% of fuel cell costs and 20% of photovoltaics costs. Renovation projects are also eligible.

Bruce Fowle, senior principal at New York architect Fox & Fowle, says that more incentives and compelling economic arguments will be needed to influence profit-driven US developers. "Everybody says they want a green building but if you tell them it will add to the cost, you'll often get a different answer," he says.

With the current low energy costs, technologies such as photovoltaics are financially unattractive, and there are few compelling reasons to move away from the standard power-hungry, air-conditioned office block. However, electricity companies could step in as unlikely heroes. Fowle says that the booming US economy is creating unprecedented power demands, and there is real concern in New York that the city will run short of power. ºÃÉ«ÏÈÉúTV new plants is politically unacceptable, so generators are beginning to offer building owners incentives to reduce their consumption.

Fowle also notes a trend towards cleaner, greener interiors. Widespread outbreaks of "sick building syndrome", and employee health problems caused by poor working conditions, have made building users more demanding. Owners, meanwhile, realise that better conditions can lead to better productivity.

Fowle rattles off a bottom-line argument designed to convince even the most hard-nosed building owner: "Greening a building adds 10% to the cost. Natural light and good air quality can improve productivity between 6 and 16%. Some 15% of corporate cost is in buildings, while 85% is labour. Labour costs in a New York building are $375/ft2. If you can improve productivity by 10%, you're talking $37.50/ft2."