The greatest CO2 emitters are buildings, responsible for 40% ofemissions, presenting an enormous opportunity for builders. Even asother sectors are struggling, sustainable building is growing at a30% annual rate, making it the fastest-growing sector in thebuilding industry, said David Gottfried, CEO of Berkeley, CA-basedRegenerative Ventures and a founder of the U.S. Green BuildingCouncil. "The growth in this world right now is green," Gottfriedsaid.

CenterBuild is held annually for developers, designers andconstruction professionals in retail real estate. And retailers areleading the way in greening this sector, particularly since it canbe profitable, said Joseph Feldman, managing director and seniorresearch analyst of New York City-based Telsey Advisory Group: thepioneering 'green' Wal-Mart in Lawrence, KS, postedhigher-than-average sales for the chain.

Wal-Mart is not alone in pursuing sustainability, he reported:Target is starting to place motion sensors in their stores thatwill dim lights in unoccupied aisles. The Gap and the Limited alsoare making efforts at energy efficiency, with the latter replacingroofs at three distribution centers to make them more energyefficient.