Blue-green and blue roofs are increasingly promoted to adapt to climate change by providing multiple benefits. However, uncer-tainties about their design and how they differ from conventional green roofs hinder their implementation. This studyinvestigates the potential of green, blue-green, and blue roofs to control urban stormwater and improve microclimate by moni-toring their performance in Toronto, Ontario, Canada. Experimental setups were built and varied with the following designfactors: substrate type and thickness, drainage layer thickness and orifice size. The results revealed that blue-green roofswith organic and FLL (blended according to the German Forschungsgesellschaft Landschaftsentiwicklung Landschaftsbau) sub-strates significantly improved detention compared to green roofs with similar substrates. The organic blue-green roof achievedmaximum retention, but FLL blue-green roof did not have higher retention than FLL green roof. The blue roof with smaller ori-fices had comparable hydrologic performance to vegetated roofs but suffered from long water standing durations. Organicsubstrates followed by FLL substrates result in the highest air cooling in the noon, but blue roofs had the highest air coolingin the evening. In-substrate temperatures in blue-green roofs were lower than those in green roofs. Trade-offs between thebenefits and drawbacks need to be considered in future designs.
Almaaitah, T; Drake, J; Joksimovic, D
Impact of design variables on hydrologic and thermal performance of green, blue-green and blue roofs
Blue-Green Systems