“Greenroofing” is a popular trend, and rightly so. But what is a green roof, really? The EPA defines a green roof as “a vegetative layer grown on a rooftop” and includes two main different types, extensive and intensive green roofs. Extensive green roofs include vegetation suitable for an alpine environment with minimal maintenance, whereas intensive green roofs, typically heavier systems, resemble traditional parks and require more maintenance and investment.
So how could a green roof benefit you?
There are numerous environmental, economic and social benefits.
Environmentally, green roofs provide a variety of benefits. Not only do they reduce greenhouse gases and increase biodiversity, but green roofs help in managing stormwater and reduce the urban heat island effect. According to The Green Roof Research Program at Michigan State, erosion, flooding and pollutants such as sewage are controlled and diminished through green roofs. In fact, according to the EPA, extensive roofs can typically “capture between 50 and nearly 100 percent of incoming rain” while intensive roofs have the capacity to capture more. Similarly, through evapotranspiration (the movement of water from the Earth’s surface to the atmosphere) green roofs “provide shade and remove heat from the air… reducing temperatures of the roof surface and the surrounding air.” This is important to reduce urban heat island effect in which urban areas, due to human activities, are warmer than surrounding rural areas.
Economically, Michigan State University has demonstrated green roofs to be a great investment to increase property value, promote job creation, extend roof life, and save money in the long term. They note that local economies are promoted through the “construction and maintenance of green roofs [providing] business opportunities for roofing contractors, plant producers, landscape designers and contractors, and other green industry members…” Similarly, green roofs protect your roof from UV radiation, temperature, and other weather. The National Park Service states, “A well–maintained green roof can more than double the number of years before a roof needs to be replaced compared to a standard roof, making up for some of the added costs of installation.” This, combined with Michigan’s reported $200,000 you can save over a roof’s lifetime from energy conservation is an example of how green roofs are a worthwhile investment.
Source: Intermountainroofscapes.com
Socially and health related, green roofs offer unique benefits. Green roofs aesthetically pleasing and improve air quality, and they provide urban amenities where recreational or relaxation activities such as gardening can be done. Additionally, noise cancellation, from the layers and vegetation in a green roof, is an overlooked aspect. According to Lindum green roofs, some mats for green roofs can reduce sound by 40 dB, a benefit for urban environments where noise pollution causes psychological, sleeping, cardiovascular and hearing issues.
Negatives:
However, there are some significant negatives when it comes to installing green roofs. For one, traditional green roofs according to greenroofers.co.uk, “will add between 50 and 200kg/metre squared to an existing rooftop” with few roofs like flat roofs able to maintain the weight without newly implemented structural support. The beginning process of installing green roofs can be a long, strenuous process, with a high initial cost for materials and labor. Long term maintenance of green roofs can become arduous with weeding, watering, and regular inspections, and costly consequences to restore if damaged.
Montgomery County Examples:
Wilson Wims Elementary School Roof (source: LiveRoof.com)
After installing a 38,000 square-foot-vegetative roof, Wilson Wims Elementary was among the 20 other MCPS schools with LEED certified Gold. LEED, or Leadership in Energy and Environmental Design, verifies a building is aimed at improving performance in “energy savings, water efficiency, CO2 emissions reduction, improved indoor environmental quality, and stewardship of resources and sensitivity to their impacts” according to Boston University. Green roofs, according to greenroof.com, contribute “at least 6 LEED points” and “up to a possible 15 or 16.” Overall, the greatest benefit of the installations in these schools may be the message it sends to being an environmental asset, according to Jim Snyder, the grower for LiveRoof, but how it “just as importantly provides opportunities for students to observe and learn about the importance of environmental stewardship.”
So, how do you install one?
Although there are many promising green roof styles and DIY installation options out there, it is recommended green roofs be installed by professionals like Up Top Acres, LiveRoof, Furbish, and more to ensure longevity and effectiveness. Furthermore, in Montgomery County, with no residential zoning requirements and a multitude of incentives and rebates easily found on mygreenmontgomery.org, green roofs can be easily and inexpensively installed in your home and community to provide a multitude of environmental, economic, and social benefits.
By Emma Goodwin, B-CC High School
Citations:
Benefits of Green Roofs . Retrieved November 7, 2017, from http://www.greenroof.hrt.msu.edu/benefits/index.html
Green Roofing Installation & Design. Retrieved November 2, 2017, from http://www.greenroofers.co.uk/
Green Roof Benefits. Retrieved November 9, 2017, from http://intermountainroofscapes.com/benefits
Green roofs help schools meet LEED standards. (2016, July 7). Retrieved November 14, 2017, from http://www.nurserymag.com/article/green-roofs-help-schools-meet-leed-standards/
- (2017, January 13). 7 Pros and Cons of Green Roofs. Retrieved November 8, 2017, from https://greengarageblog.org/7-pros-and-cons-of-green-roofs
How do Green Roofs work? Retrieved November 7, 2017, from https://www.renewableenergyhub.co.uk/green-roof-information/how-do-green-roofs-work.html
How to Maintain Your Green Roof. (2013). Retrieved November 8, 2017, from https://www.montgomerycountymd.gov/DEP/Resources/Files/PostersPamphlets/Green-Roof-Maintenance.pdf
Is a Green Roof Right for You? Retrieved November 8, 2017, from https://www.greenamerica.org/green-roof
Incentives & Programs. Retrieved November 6, 2017, from https://mygreenmontgomery.org/incentives/
LiveRoof Green Roofs Help Montgomery County Public Schools Set the Gold Standard For Green Schools. (2016, July 6). Retrieved November 9, 2017, from http://www.liveroof.com/liveroof-green-roofs-help-montgomery-county-public-schools-set-the-gold-standard-for-green-schools/
Reducing Urban Heat Islands: Compendium of Strategies – Green Roofs. Retrieved November 9, 2017, from https://nepis.epa.gov/
Using Green Roofs to Reduce Heat Islands. (2017, June 09). Retrieved November 7, 2017, from https://www.epa.gov/heat-islands/using-green-roofs-reduce-heat-islands
What is LEED? Retrieved November 14, 2017, from http://www.bu.edu/sustainability/what-were-doing/green-buildings/leed/
