BSA Lifestructures

Financial benefits of a green roof

Dan AdlerApril 22, 2016

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The value and benefits of installing a green roof are becoming more apparent in the design and construction industry. A green roof covers a roof with vegetation and greenery that is planted on a waterproofing membrane. Truth be told, green roofs offer a ton of functional and aesthetic benefits to many building types. Below are three fiscal reasons why your building should add a green roof.

1. Reduce Energy Use

Green roofs improve the insulation qualities of a roof, which reduces heat flow and cooling loads that can greatly decrease building energy costs. In the winter, the soil and vegetation help buildings retain heat and lessen heating costs. During summer, the transpiration process of green roof plantings reduces the ambient air temperature and lower HVAC cooling loads.

At Purdue University’s M. Katherine Banks Green Roof Laboratory, a graduate student conducted research to quantify the insulation value of green roofs. The study found that in the summer months the green roof reduced heat flow by 70 to 90 percent. And in the winter, the roof reduced heat flow by 44 percent.

2. Reductions in Storm Water Management Systems

Conventional detention ponds require sizeable land area and excavation costs on new building projects. Especially in areas with high land values, this is a large cost that can’t be recovered in leasable space. Similarly, precast stormwater quality units are costly to install and maintain. A green roof captures stormwater where it first hits a site. The plantings and soils capture the rain water, filter out pollutants, hold and then slowly release the water reducing the downstream flow.

Many jurisdictions are now offering credits in stormwater permitting for installing a green roof – reducing the size and cost of at grade storm drainage solutions.

3. Longer Roof Life

Green roofs reduce physical, chemical and biological stress that can break down a roofing membrane. They also protect the waterproofing from UV exposure, which accelerates the aging process. The summer cooling and protective surface that is naturally built in to a green roof system blocks extreme heat, sunlight, and precipitation.

A typical roof life is 15-25 years. A green roof can extend a roof’s life by two to three times. In Germany, where a lot of the green roof technology was developed, green roofs have been in place on buildings for over 100 years.