“It’s just a few hundred square feet… how can one green roof make that much of an impact on our environment?”
We’ve heard this question and others like it posed numerous times through our work as landscape architects. In many cases, it can be difficult for some to understand the value of a green roof given its high upfront cost.
On Thursday, May 23 Hunter Beckham presented at the CETCO Building Envelope University in front of more than 50 allied professionals. The topic – the economic and environmental impacts of green roofs. The approach, however, was to look beyond the size and material of the green roof, and instead look at its effects in terms of scalability.
Think of one 600 sq. ft. green roof. By itself, the roof saves the owner $436 annually in energy costs. Additionally, the green roof eliminates more than 8,000 gallons of stormwater runoff into nearby water bodies. That’s fairly respectable, right? Now, take that same green roof and extrapolate it across a typical neighborhood cross section. Now you have about 36 homes (of about the same size) each with its own 600 sq. ft. green roof. Suddenly, the annual energy savings are just over $15,000 and the number of gallons of stormwater eliminated is just under 290,000 gallons – that’s equal to filling 6,000 bathtubs!
At this point we have to mention that the data is estimated based on several assumptions and averages. However, the impact is substantial when you begin to look at the intangibles – the social, economic and environmental benefits. For example, green roofs increase property values, bolster community pride and increase employee retention. In healthcare situations, green roofs positively impact patient health and recovery, and serve as a respite for staff in urban situations.