TORONTO - Green roof square footage on buildings in the United States increased by more than 80 percent from 2004 to 2005, according to Green Roofs for Healthy Cities (GRHC), a trade association. Green roofs are rooftop vegetation that helps reduce storm water runoff; insulate against heat and sound; and increase energy savings. They also help reduce urban heat island effect, which is caused by dark urban roofs, pavement, and other infrastructure absorbing the sun's heat.

The GRHC recently completed its first survey of its members to gauge the growth of green roofs, finding that in 2005, green roofs covered at least 2.5 million square feet of roof space in North America, up from 1.3 million square feet in 2004. Cities that incorporate the largest area of green roofs in 2005 include Chicago, Washington, D.C., and Suitland, Md. Toronto may catch up to these other cities quickly, since the city council recently passed a policy that requires green roofs to be incorporated into city buildings and provides financial incentives for green roofs.

The GRHC is currently gearing up for its annual conference, to be held May 11 and 12 in Boston. For more information, visit www.greenroofs.org.