What are the benefits of a green roof? One of the first major benefits of a green roof is that it acts as another thermal barrier for the roof. It adds mass and greater thermal resistance, thus letting less heat to enter the house during the summer and letting less cold to permeate through the roof during the winter. A green roof can also greatly extend the life of the physical roof and membrane (if properly installed) since it acts as a physical barrier between the elements and the roof. One of the greatest benefits for the city itself, especially such a dense, urban one as Philadelphia, is how much it reduces stormwater runoff and the heat island effect. The plant material and soil absorb the water, allowing it to naturally evaporate, rather than picking up pollutants from ashphalt, cars, etc and entering into city's overworked runoff sewer system. The vegetation and soil help to filter pollutants and carbon monoxide as well. The primary contributor to the heat island effect (large cities being a few degrees warmer than the surrounding areas) are typical black roofs. Black absorbs the sun's rays and stores the heat, releasing it back out generally at night. White colored roofs and green living roofs help reduce this effect by not retaining the heat. Lastly, green roofs are simply much more pleasing to look at that your typical roof. It gives a living, vegatative oasis in the middle of the dense city where yards are not often an option. More to follow on Green Roofs in upcoming posts.