The University of Toronto’s Green Roof Innovation Testing Laboratory (GRIT Lab) at the John H. Daniels Faculty of Architecture, Landscape, and Design has launched a new research project and web application that will expand its investigation of the performance of green roofs in Canadian urban environments, and allow it to better share the results with the broader public.
This spring, the GRIT Lab’s multidisciplinary research team launched phase II of its research: an investigation into whether solar panels and green roofs can work in concert. At present, green roofs and solar panel companies regularly compete for space on industrial, commercial and high-density residential rooftops, though they both provide significant environmental benefits. But does the green builder really have to choose one or the other?
“We are interested in finding out whether green roofs can improve the energy production and lifetime of PV arrays through increased cooling by the green roof vegetation,” says GRIT lab’s director Liat Margolis. “Very little published data currently exists on the practicality of integrating solar panels with green roofs.”
This spring, the GRIT lab built the first and only green roof integrated PV research site in Canada on the roof of 230 College Street. The new installation includes 40 solar panels, arranged in four rows and suspended at two different heights (2 ft. & 4 ft.) above extensive green roof beds.
Green roofs improve urban stormwater management and energy efficiency, increase habitat, and provide aesthetic value. Solar panels are a source of renewable energy. In addition to testing the potential evaporative cooling effect of green roofs on solar energy production (PV panels perform better, energy wise, when they are cooler), the researchers will examine the effect that the shade cast by the solar panels will have on plant growth and the green roof’s ability to help keep the panels cooler. They will also review the water retention capacity of the green roof under varying climatic conditions.
“The research results will benefit the green building industry by producing Canadian-based performance data, generating design guidelines and tools, and building technical experience that can be applied to the next generation of sustainable building design,” says Co-Researcher, Civil Engineering Professor, Jennifer Drake.
This project is supported by a Natural Sciences and Engineering Research Council of Canada (NSERC) Strategic Partnership grant, led by Civil Engineering Professors, Brent Sleep and Jennifer Drake and Landscape Architecture Professor, Liat Margolis in collaboration with industry partners, Sky Solar, Bioroof, IRC Building Science Group, and DH Water Management. Additional support is provided by: Schletter, Semple Gooder Roofing Corporation, Siplast, TerraGen Solar, Tremco Roofing, University of Toronto Facilities & Services, and the Daniels Faculty.
The Grit Lab launches the Green Roof Image Index
The GRIT Lab is now able to share photo documentation of phase I of its research through its online Green Roof Image Index. The webpage displays time-stamped photos of its 33 (4 ft. x 8 ft.) green roof test beds atop 230 College Street, and is designed to highlight the development of the green roof thoughout the GRIT Lab’s 5-year study.
Each of the 33 test beds varies in terms of growing media composition and depth, plant type, and irrigation schedules. With the click of a mouse, visitors to the site can select any of these variables to instantly isolate photos of beds that share elements of interest. How do beds containing ‘meadow’ plants and a high proportion of compost — for example — perform when the only water they receive comes from rainfall? Photos of the boxes with no set irrigation schedule look dry during the peak summer months. Those that are regularly watered are lush and green. A timeline bar at the top of the page allows you to scroll through various months of the growing season to view how the vegetation changes from spring to fall.
“Ultimately, the aesthetic quality of roof gardens and plant growth is very important to designers” Margolis says. “This tool could be beneficial to designers specifying green roof components and maintenance practices.”