The Daniels Faculty’s Green Roof Innovation Testing Laboratory (GRIT Lab) has expanded its research to include an investigation into the performance and benefits of green walls in the context of Toronto's climate and at elevated heights. The Lab's study focuses on the leaf coverage of several vine species and their influence on the thermal regulation of a building envelope.
On September 4-5, 2014, they presented a poster at the 1st International Conference on Green Walls in Urban Areas which was held at the Green Wall Centre in Staffordshire University, UK. On September 20th, 2014, they presented their latest findings at the International Plant Propagators’ Society (IPPS) Conference which was held in Niagara Falls, Ontario.
The research team examined the thermal cooling performance of three vine species (Hops, Virginia Creeper, and Riverbank Grape) on a 3-dimensional welded wire frame against a south-facing wall on the rooftop of the Daniels Faculty. A temperature sensor was attached to the surface of the exterior wall, and immediate behind each of the vegetated façades and the three control façades (trellis, but vegetation-free). Temperature data was recorded every 5 minutes and then compared against the onsite weather station data (ambient temperature, solar radiation, relative humidity) for change in the temperature reduction over the growing season.
Research to date shows that from May to September, the green façades kept the wall surface on average 1.84°C (3.31 F) cooler. The Grape vine performed best over this period, reducing surface temperatures by 2.91°C (5.24 F) in September.
In all three species, wall temperature dropped as the vegetation cover increased over the growing season. The effect of vegetated cover on wall cooling was most apparent in Hops which re-grows from root stock and basal stems to cover much of the trellis by the end of the growing season. (Grape and Creeper retained some of their leaves and wall cover over winter and therefore provided move cover in spring.)
For more information on the GRIT Lab, visit http://grit.daniels.utoronto.ca/