With climate change, precipitation events are increasing in frequency and intensity across the globe. Drier, hotter summer months are driving cooling loads for buildings to be higher, while facing capacity concerns for draining impervious areas including buildings and surrounding areas during more frequent storms. Cities with aging infrastructure and high densities face difficulty to convey stormwater runoff into drainage systems whilst simpler solutions such as increasing the number of pipes or sizes are challenging to implement in built-out areas. “Connected blue-green” roofs are a concept that aim to provide the benefits of green roofs, with improved water retention capability, and added water detention.
Healthy green roofs reduce cooling loads and retain water. However, green roofs underperform if the vegetation is not healthy or dries up. Dry vegetation during drought pose a fire risk while holding more heat on the roof, and increase building cooling loads. In the meantime, blue roofs are emerging in urban areas that see large amounts of precipitation, enabling the use of captured water in place of potable water where applicable. Connected blue-green roofs are a hybrid solution that aim to combine the benefits from green-roof vegetation and an improved blue roof water retention and detention. Using the blue roof principles to capture runoff into cavities that can feed into a green roof when the vegetation is in need of moisture could provide a lasting solution.
This presentation provides an overview of a research that compared various roof types to infer on the heating and cooling load effects, stormwater management, and the vegetation’s health. Read the research thesis and learn more about vegetated roof systems by visiting BCIT's Institutional Repository.
Harveer (Harvy) Singh Takhar, P.Eng., M.A.Sc.
Utilities Engineer, City of Delta
Harvy Takhar, P.Eng., was born and raised in Delta, BC, where he played hockey, soccer, and attended school. Harvy completed his undergraduate studies at the University of British Columbia in the Department of Mechanical Engineering. Harvy works as a municipal engineer and has a keen interest in green engineering and sustainable development. As a municipal engineer, Harvy is involved with the living dike pilot project. Harvy's passion for green infrastructure was ignited through the British Columbia Institute of Technology's part time Masters of Applied Sciences program. While researching sustainable solutions, Harvy came across an opportunity to quantify the benefits of applying effective green engineering solutions to roofs. With the help of Dr. Rodrigo Mora, Harvy developed an initial experimental design. After meeting Robb Lukes from the City of Vancouver and several other stakeholders including IKO, Harvy was able to move the research forward with the instrumental support of Dr. Rodrigo Mora. The research and demonstration project has been publically constructed at the Helena Gutteridge Plaza at the City of Vancouver City Hall and data was reported on for Harvy to obtain his Masters of Applied Sciences. Harvy is now serving as the Chair of Richmond/Delta Branch of Engineers and Geoscientists BC.
