IN NEW YORK, saving energy with green roofs: “This month, Gov. David A. Paterson approved tax abatements to developers and building owners who install green roofs, or a layer of vegetation and rock that absorbs rainwater, insulates buildings and extends the lives of roofs. . . . Temperatures on buildings with green roofs are up to 30 percent lower during the daytime in the summer than they are on those with conventional roofs, which means that tenants on the floors below do not have to run their air-conditioning as much.”