Walls shrouded in forest green, and lined with leather-bound volumes. Spacious, carpeted offices, draped with expensive fabrics and filled with mahogany furniture. Space to confide a legal breach, or negotiate with a departing spouse. Corridors lined with conference rooms. That's the stereotypical law office ā€” sprawling, energy-guzzling with its lights and electronics and the cost of heating and cooling its generous square footage.

But now, many of the nation's 1.2 million lawyers have caught the green wave, and their offices are changing.

A new report by real estate services firm CB Richard Ellis (CBRE) says many top law firms are taking stock of their energy consumption and carbon emissions, and changing their strategy.

Law offices traditionally demand high square footage per attorney, with their massive file storage and library requirements, and sky-high lighting costs, particularly since employees spend many evenings and weekends poring over legal tomes. But the new trend is to shrink attorney space with open floor plans, shared workstations, and team environments.

In general, the space allotment is falling from the traditional range of 800 to 1,000 sq. ft. per attorney to 500 to 700 sq. ft. per attorney, according to CBRE's law firm practice group in the new report, Law Firms Build a Case for Green: Recent Trends in Law Firm Sustainability Practices.

ā€œSustainability programs have grown increasingly common among law firms,ā€ says Sally Wilson, CBRE's global director of environmental strategy. Some firms not only pursue LEED certification through the U.S. Green Building Council, they also use it at overseas branches.

A number of legal offices now store hard-copy files off-site, while new technology reduces lighting costs. Some law firms use wireless HVAC control systems, which shrink installation costs.

In Chicago, the law firm Nixon Peabody tore down its walls and started fresh, installing windows along office corridors to let in natural light while protecting the privacy of clients with new techniques for the glass.

Going green starts with site selection. In locating its Atlanta office, the firm Seyfarth Shaw LLP picked a building in Midtown that was already LEED certified, the report notes.

Heating and cooling costs can be reduced through sub-metering, which allows tenants to be charged only for the energy they use, rather than being assessed a percentage of all energy consumed in a building.

A study by CBRE and the University of San Diego's Burnham-Moores Center for Real Estate shows that separate energy metering can help companies save up to 21% on electric and gas costs.

Most U.S. law firms are small. The American Bar Association (ABA) reports that 76% have two to five lawyers, while 13% have six to 10 attorneys. Only 5% had more than 20 attorneys as of the year 2000.

Of the 1.2 million lawyers licensed in the U.S. as of 2008, the largest group (74%) was in private practice, while 8% were in government and 8% in private industry.

Across the country, attorneys make up one of the largest segments among office tenants. The ABA, for instance, says it is the largest voluntary professional association in the world, with 400,000 members.