Green roofs and walls are not just good for the environment and human health, they also provide economic benefits to the property owner and the community as a whole. There are a number of ways that green roofs and walls save money over time. Here are some of their economic benefits.
- Extend the life of the rooftop. The life of the roof the underlying roof waterproofing members can be extended by using green roofs to sheild the roof from the effects of ultraviolet radiation, temperature extremes and mechanical damage. Vegetated areas heat up much less than exposed surfaces of asphalt or bitumen. According to greenroofs.com, “reduced stresses on roofing materials typically double the service life, prolonging the practical life by 20 years. Other estimates say a green roof can actually triple the life of its roof.”
- Reducing cooling loads by up to 25%. A 2012 NRDC research paper discusses a case study of a two-story office building in Athens, Greece, where a green roof reduced teh cooling load for the building’s top story by 27-58% per month between May and September. The NRDC goes on to state that green roofs result in overall annual cooling load reductions of up to 25%, depending on building and green roof characteristics. These estimates do NOT include savings from making HVAC systems more efficient. Generally, air-conditioning systems begin to lose operational efficiency at about 95º F. Green roofs reduce rooftop temperates significantly.
- Municipal incentives and avoided costs. It’s the carrot and the stick. A growing number of municipalities are offering tax abatement, credits, FAR bonuses and other incentives for installing green roofs and walls. Even without those, most municipalities are requiring new projects to handle their stormwater runoff on site. And, to the extent stormwater is handled on a project by project basis, the cost of fines for violations of the Clean Water Act are avoided.
The 6700 square foot hybrid green roof that Greensulate installed on the luxury condominum project – The Chocolate Factory – in Brooklyn, New York (pictured above) received New York City’s first Green Roof Tax Abatement credit.