n a bid to stand out in a sagging housing market, an increasing number of real-estate agents are marketing themselves as eco-friendly -- connecting environmentally conscious buyers to "green" homes and helping sellers make their homes more eco-sensitive.

These agents are promoting their knowledge of eco-friendly and energy-efficient properties on their Web sites and blogs. Some are taking courses to learn about things like geo-thermal heat pumps and how to help home buyers qualify for grants and tax credits for energy-saving improvements.

Yet some housing experts question whether some agents are using a cursory knowledge of green building as a marketing ploy in a tough market. "A Realtor may support [a purchase] regardless of how green the home is," says Jay Hall, acting director of the eco-friendly homebuilding program at the U.S. Green Building Council in Washington.