Abstract
Four roof assemblies were constructed at Helena Gutteridge Plaza in Vancouver, British Columbia, Canada to compare the stormwater management capabilities and relative thermal performance. A conventional, green, blue, and connected blue-green roof were equipped with sensors to record roof temperature profile, runoff, and soil moisture content data from January 2020 until August 2021. The blue and connected roofs had a water cavity of 85mm with wicking fabric to store water. The green and connected roofs had sedum mats as vegetation with 100mm and 75mm of soil respectively. The vegetated roof assemblies lowered the surface temperature by up to 50% during summer compared to the conventional roof’s peak surface temperatures reaching over 60°C. With available water, the green, blue, and connected roof assemblies are able to reduce internal temperatures by up to 4°C in the summer. As long as there is available water for the blue. Green, and connected roof assemblies, they can effectively reduce internal and surface temperatures. Over a period of 2 years, the green roof was able to retain 23.3% of the rainfall while the connected and blue roofs retained 20.2% and 17.3% respectively, compared to the conventional roof. During warmer months between May and September, the connected roof was able to retain 100% of the runoff while its vegetation outlasted the green roof’s vegetation during drought by 3 weeks in 2020 and 2 weeks in 2021. The blue roof retains 96% of rainfall during summer while the green roof retains 91% due its lack of storage compared to the other assemblies. The blue and green roofs were better able to delay the peak flow and reduce it with less overall runoff during winter compared to the connected roof. The vegetation of the connected roof was taller, more vibrant, and had more ecological activity than the green roof and also resulted in a higher saturation moisture content.