Green Roof Buildings Zach Berger Madeline Cotter Patrick Hurley Ryan Skinner The University of Vermont
Definitions A green roof is a vegetated alternative to conventional rooftops. Extensive green roofs are shallow (1-6”), constructed by assorted trays or layering soil, substratum and small plants on an impervious roofing membrane. Intensive green roofs are deeper (6”+) and often involve particular drainage controls, more complex plantings and additional structural requirements.
Aiken Center Research Green Roof •Testing the impacts of green roofs on storm water management. •Rooftop split into 4 “treatment watersheds” with artificial slopes. •One control watershed (conventional rooftop), three treatment watersheds comparing plant species and soil media. •Assembled with 2’x4’ modular trays – allows for maintenance of roof and watersheds with ease. •‘Tipping buckets’ in third floor of Aiken Center allows for runoff monitoring and sampling.
Opportunities for UVM •Green roofs count as credit towards LEED certification. UVM has a policy of requiring LEED Silver or higher for every new or renovated building. •Burlington Combined Sewer frequently overflows due to peak loads during storms – reducing runoff could greatly lower pollution rates to Lake Champlain. •Combined with other practices such as rain gardens, vegetated swales and constructed wetlands, UVM could potentially capture and improve all of its stormwater on site.
Case Study: ASLA
http://www.uvm.edu/rsenr/enews/?Page=news&storyID=15587&category=rsenr
Green Roof Development at UVM University Heights North & South – 2006 •~5,500 ft2 • Leisure/recreational spaces •Grasses, trees, garden beds, patios •Built by Natural Landscapes Architects http://www.uvm.edu/~arch/projects/images/greenroof.jpg
American Society of Landscape Architects study •74% reduction in stormwater runoff. • Virtually runoff free in storms of less than one inch • Raises pH (lowers acidity) of runoff, lowers peak flow rates, reduces nitrate pollution. • Concerns: lowers dissolved oxygen, raises chemical oxygen demand, orthophosphate, total phosphorous, total suspended solids, total dissolved solids. • Heavy metal leaching from substratum and membranes a concern, but levels still remain below EPA regulations.
Davis Center Loading Dock – 2007
Challenges •University Heights North/South plagued with leaks, faulty flashing and membranes. •Aiken Center restricted to researchers, maintenance personnel due to liability. •Snow loads, droughts, overflow control concerns. •Additional cost of installation. •Many buildings unfit for retrofit due to age, sloped roof, historical building restrictions. •Who is responsible for maintaining after installation?
SOURCES: Glass, C. (2007). Green roof water quality and quantity monitoring. (Doctoral dissertation, Howard University)Retrieved from http://www.asla.org/uploadedFiles/CMS/Green_Roof/Green_Roof_Water_Monitoring_Report.pdf
http://www.hkw-p.com/projects/educational/university-vermont-dudley-h-davis-center
• ~19,400 ft2 • Grasses, turf grass • Aesthetics, storm water control, leisure space, • Built by Landshapes, Richmond, VT
Green Aiken Center – 2012 •6,760 ft2 •Research, storm water control •Sedges, cacti, mosses, sedums •Contact: Gary Hawley, Rubenstein School of Environment & Natural Resources http://beta.renotahoemoms.com/apps/pbcs.dll/gallery?Site=BT&Date=20121102&Category=LIVING09&ArtNo=211020801&Ref=PH&Par ams=Itemnr=5&rgj_description=&rgj_date=November%202.%202012
The Next Steps Better Communication! Engage students, staff, faculty and the public on the existing green roofs throughout campus. •Better Design! Aiken Center research results may lead to better design, installation and understanding of the benefits of green roofs and their feasibility on UVM campus. •Better Planning! There is currently no policy on the use of green roofs for campus stormwater management. Begin the conversation. •Better Questions! Do green roofs only make economic sense on new buildings? Is it cheaper or more effective to divert the water to rain gardens? Submit proposal to Clean Energy Fund for feasibility study. •Better and Better! Special topics class to retrofit existing roofs.