More office developers are going green, according to a report in the Philadelphia Business Journal. According to that article, green office space in the United States now totals 500,000,000 square feet. The U.S. Green Building Council (USBC), a Washington-based coalition of industry professionals, says the green building market is now valued at approximately $7 billion.

Another sign of the growth of the green building movement is the increasing number of architects, designers and other professionals in the construction industry who have become LEED-certified. According to the Philadelphia Business Journal article, at the beginning of 2006, 23,100 construction professionals had earned LEED accreditation. LEED-certified professionals must demonstrate knowledge of green building practices and the LEED green building rating system.