An innovative idea for energy conservation appeared in the op-ed pages of yesterday’s Seattle Times. Seattle City Councilmember Peter Steinbrueck makes the case for "green roofs" on Seattle’s buildings. Roofs covered by a thin layer of growing plants have a natural insulation that reduces energy costs (to the tune of nearly $150,000 per year at the new Justice Center, which sports a green cap). They also filter pollution and reduce noise. And they’re pretty to boot.