Green Roofs - Living Architecture Monitor - Fall 2011 - (Page 8)

ON THE ROOF WITH… the humid south and arid southwest where rapid development is outpacing waterresource replenishment. Our team consists of seven professors— two engineers, one climatologist, one horticulturalist, one fish and wildlife biologist, a land policy expert, and myself, the landscape architect. Students that I advise are examining the microclimate benefits, biodiversity, stormwater mitigation, and air pollution benefits of extensive green roof systems commonly found on Midwest residential housing structures. We have competed nationally with our green roof design solutions at this year’s U.S. Environmental Protection Agency’s Planet, People and Prosperity (P3) competition. We also have published and presented our green roof findings at a number of national and international professional meetings. Can you share some of these ﬁndings with us? JW: Design of extensive (shallow) green roof systems for residential structures will demand greater maintenance and care in plant selection. The sloped nature of most residents (i.e., 4:12 roof runs) creates a new dynamic in the water demands of an extensive green roof system. This is due to significant differences in the solar incidence occurring throughout the day on different parts of the roof system; solar incidence directly affects the temperature and moisture regimes of the roof system. The south exposure of the roof will have the most severe temperature and moisture limitations, which will affect plant cover on the system and its overall performance in terms of microclimate modification, stormwater management, and biodiversity support. We also examined various green roof systems for biodiversity in bird and insect populations. These studies are just being completed, and the data from them will be coming out shortly. However, one important finding that can be shared at this point is that all types of green roof systems (from shallow to thick) support a wide array of insects, which are important food sources for song birds. Our stormwater study of green, brown and conventional roofing material (steel and fiberglass shingle) systems shows significant differences in the volume and release time between a rain event and the release of water from a roof system. Green roofs (and even brown roofs—i.e., roofs with soil media but no vegetation) have a substantial capacity to reduce peak flow following a rain event, and they need to be considered as a best management practice in areas where stormwater flows have a severe effect on the water quality/quantity in a watershed. Lastly, our recently collected results of a state-wide survey in Michigan entitled “Perceptual Barriers to Residential Green Roof Adoption in Michigan” found that green roofs would receive wider, more favorable acceptance if more information on the technical aspects of the systems were available. Cross-tabulations on the data set will tell us more about the residents who are inclined to consider green roof adoption, and that analysis will be coming shortly. Good luck with all of your work, and thank you for your time to share your expertise with us. JW: You are most welcome. Caroline M. Nolan is the editor of the Living Architecture Monitor and principal of ThinkSustain®, a boutique sustainability consultancy in Toronto, Ontario. http://www.nationalgreencentre.org http://www.nationalgreencentre.org http://www.gettag.mobi

Table of Contents for the Digital Edition of Green Roofs - Living Architecture Monitor - Fall 2011

Green Roofs - Living Architecture Monitor - Fall 2011
Contents
From the Founder
Strata
On the Roof With…
Research
Marketing
Policy: The Game Changer
Policy: Toronto’s Green Roof by-Law
Policy: Energy Code Break-Through
Tools
GRHC: Update
GRHC: Welcome New Members
On Spec

Green Roofs - Living Architecture Monitor - Fall 2011