Efforts to create green building REITs, brought to a grinding halt by the credit crisis and recession, are unlikely to resume until late in the economic recovery when new construction rebounds--but a number of existing REITs are already going a lot greener.

"These estimates are rough, but I'd estimate that about 20% of the new space being acquired or built by U.S. REITs is green rated and probably about 40% of REITs hold some type of green property," says Gary Pivo, a professor at the University of Arizona and co-director of the Responsible Property Investing Center (RPIC, www.responsibleproperty.net).

No comprehensive list of socially responsible REITs currently exists. Pivo is developing a prototype Responsible Property Investment Index through the RPIC which he hopes to have up and ready by the end of next year. "There are some REITS doing a good job by some accounts. Examples would be Liberty Property Trust and ProLogis," he says.

Liberty (NYSE: LRY), a major developer of high-performance green office and industrial buildings, received The U.S. Green Building Council's 2006 National LEED (Leadership in Energy and Environmental Design) Corporate Leadership Award. It currently has 41 LEED or green projects completed or under development in the U.S. and U.K. These projects, representing $1.3 billion in investments, total nearly 7.8 million square feet, says chairman, president and CEO Bill Hankowsky.

Green initiatives "are a long-term key component of our strategy," says Hankowsky. "We believe it's the right thing to do, it's beneficial to our customers, and it's a good thing for our shareholders."  Greener buildings, more attractive assets, have lower operating costs and can increase worker productivity.

Since last year, Liberty has been aiming its green efforts at its existing portfolio through energy audits, lighting retrofits, and installation of building-wide area network (BWAN) energy monitoring systems to track tenants' real-time energy use. "Our goal is to get our whole portfolio 20% to 30% more efficient than a year ago within three years," he says.

ProLogis (NYSE: PLD), a leading global provider of distribution facilities, was recently ranked the 21st (out of 100) most sustainable company in the world in a list published by Forbes.com.  Like Liberty, it's building just LEED-certified buildings. It's also committed to reducing its carbon footprint and generating renewable energy.

Last month, ProLogis announced a second rooftop solar project with Portland General Electric which will generate energy for the utility's customer grid in exchange for rental income. Worldwide, ProLogis's 27 rooftop installations will total 13.5 megawatts of solar energy.

Other publicly traded REITs and real estate companies with the largest number of LEED registered or certified buildings include AMB Property, Boston Properties, Brookfield Properties, Corporate Office Properties Trust, Forest City Enterprises, Regency Centers, Thomas Properties Group and Vornado Realty Trust, says USGBC director of commercial real estate Marc Heisterkamp.

Corporate Office Properties Trust (NYSE: OFC), whose clients are largely federal government contractors, is the top pick of Chris Lucas, a senior real estate analyst covering retail, office and industrial REITs for Robert W. Baird & Co. in Washington, D.C. He anticipates very solid earnings growth over the next five years since many of its properties are located near military installations expanding as a result of the Base Realignment and Closure Act.