A green or “living” roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. The vegetation and growing medium can either be applied directly to the roof surface or put into pots or containers so they can be easily maintained and moved. A green roof may also include additional layers such as a roof barrier, drainage and irrigation systems.
What are the Environmental Benefits of a Green Roof?
- Reduce heating costs by adding mass and thermal resistance value. A 2005 study by Brad Bass of the University of Toronto showed that green roofs can also reduce heat loss and energy consumption in winter conditions.
- Use evaporative cooling to reduce cooling loads on a building by 50-90%
- Used on multiple roofs in a concentrated area, can reduce the city’s average temperatures during the summer
- Reduce water runoff
- Create a natural habitat
- Create agricultural space
- Filter pollutants and heavy metals out of rainwater
- Filter pollutants and carbon dioxide out of the air, which helps lower the rate of respiratory diseases such as asthma
- Help insulate a building for sound—the soil helps to block lower frequencies and the plants block higher frequencies
- If installed correctly, contribute to LEED points