Green Roofs in New YorK City

Another way that building owners in NYC are looking to reduce their energy costs is by planting plants such as purple and green sedums on their roof tops. Sedum is an absorbent plant typically found in many deserts.

When the sun hits these plants on the roof, the sedums not only absorb the sunshine but cool the air when the water in their leaves evaporates. Temperatures on buildings with green roofs are up to 30% lower during the daytime in the summer than they are on conventional roofs. This means that tenants directly below these roofs do not have to run the air-conditioning as much.

These green roofs also absorb as much as 70% of rain water that might otherwise overwhelm the city's sewage system during heavy rain storms. By diverting the runoff of this water from entering the city's rivers, the city prevents millions of gallons of polluted water from reaching it's waterways.

Con Ed recently installed a 10,000 square foot green roof in July 2008. The plants sit in a mixture of volcanic rock , sandstone and other light stones capable of absorbing water.

Con Ed has teamed up with Columbia University's Climate Systems Research to evaluate the benefits and costs. Con Ed has installed roof top sensors to measure the temperature, wind and water runoff. They hope that the benefits will encourage Con Ed's client to consider green roofs.

Let's hope that they are successful.