Green roof infrastructure is a technology that allows the use of vegetation to reduce rooftop temperatures. The purpose of this study was to assess the degree to which green roof infrastructure could reduce the urban heat island in the City of Toronto. The Mesoscale Community Compressible (MC2) model was run in conjunction with the ISBA SVAT scheme and an urban canyon model at a
1 km resolution for 48 hours with the boundary and initial conditions for June 27-29, 2000. The temperatures in the lower boundary layer were compared for the base case and the case with green roofs, covering 5% of the total landmass. When green roofs in high-density areas were provided with sufficient moisture to drive evapotranspiration, temperatures across the city were reduced between 1 –2 degrees C at 1300 hours. Limited green roof coverage in an urban  area was found to intensify the cooling that could be provided by similar vegetation in the core.

Bass, B., Krayenhoff, S., & Martilli, A. (2002). Mitigating the urban heat island with green roof infrastructure. Urban Heat Island Summit: Toronto.