UofT-Sommerfeld-6264

Over the past seven years, U of T’s Green Roof Innovation Testing (GRIT) Lab at 230 College St. has found that green roofs can retain up to 70 per cent of rainwater, making them a crucial tool in reducing urban flooding. Their surface is also two degrees cooler, on average, than the air temperature – and as much as 50 degrees cooler than conventional rooftops. A second facility atop the Daniels Faculty at 1 Spadina Cres. will investigate the effect of using surface water runoff, which contains urban pollutants, to irrigate green roofs. Photos by Mark Sommerfeld