Green roof technology helps lower the cooling costs of a building by significantly decreasing the temperature of the roof and the air around A/C unit intake vents. A green roof at the Ford truck plant in Dearborn, Mich., reduced the building's annual energy consumption by 7% (Earth Pledge, 2005).
Aesthetics & Marketability
Green roofs transform underutilized, barren landscapes into verdant, urban oases. GIS studies have shown that real estate within 800 feet of green space increases in value by up to 22% (Nicholls, 2004). Green roofs demonstrate a visual commitment to local and regional sustainability.
Increased Roof Membrane Life
Waterproof membranes without the protection of a green roof need to be replaced every 10 to 20 years. With a green roof, building owners may need to replace a membrane only once during their building ownership; there are waterproof green roofs in Europe that are over 100 years old (Earth Pledge, 2005).
A 1988 study demonstrated that the availability of a natural view can be instrumental in the alleviation of daily stress and physical ailments, a decrease in the number of sick days taken, and an increase in worker satisfaction and productivity (Kaplan, 2001).
Local Food Production
A food roof can grow up to three pounds per square foot of vegetables in a season. The Fairmont Waterfront Hotel in Vancouver, B.C., produces $25,000 to $30,000 worth of herbs and produce annually (Kingsbury, 2008).
A green roof has a burning heat load of 3 kWh/m² while a three-ply bitumen roofing system, a common membrane type, has a burning heat load of 50 kWh/m² (M Koehler, 2003). This means that the heat from a fire on a green roof will be 1/16th the heat from a bitumen system.
According to the U.S. Green Building Council, green roofs can receive up to 23 LEED credits for various categories, including sustainable sites, water efficiency, energy and atmosphere, and innovation and design process.
Improved Medical Recovery Time
Studies have shown that patients recover more quickly when they have access to green spaces. Hospitals with open green spaces record patient check-out times 2.5 days earlier than hospitals without green spaces (Peck, 2008).
Green roofs can help reduce external noise pollution by 10 to 50 decibels, depending on the thickness of the system (Cities, 2006).