UBC Undergraduate Research

An investigation into new SUB rooftop garden irrigations systems Lee, Seungmin; Nan, Alexandra; Kealty, Meredith; Pan, Kevin


The new Student Union Building (SUB) is designed to be a Leadership in Energy and Environmental Design (LEED) Platinum + rated sustainable building. One of the new features of the SUB is a rooftop garden capable of producing food for businesses and food retail outlets. Vancouver has a very moist climate, with long, wet winters; however, hot, dry periods are common during the summer. Therefore, it is necessary to install an irrigation system to keep the garden sufficiently watered during these periods. There is a wide range of solutions to the irrigation problem for the rooftop garden. In order to gain or surpass a LEEDS Platinum + standing, the system with the lowest carbon footprint, and highest water efficiency must be chosen. However, due to the limited space for planting crops, the system must be effective in maintaining crop health and maximizing yield. Based on these constraints, the selected system should employ micro-irrigation. These systems are designed to apply moisture directly to the plants or root zone soil. Whiffen (1991) states “an irrigation system designed to operate at 40 psi can require up to twice as much energy as an irrigation system designed for a pressure of 10 psi”. As micro-irrigation systems send water near the root zone, it saves water from evaporation and runoff, reducing energy costs. Additionally, “the ability of micro-irrigation systems to place most of the irrigation water where it can be used by the crop reduces the amount of which needs to be pumped through the irrigation system to supply the entire crop water needs” (Whiffen, 1991). An 80 percent improvement in water efficiency was observed by using micro irrigation systems, as opposed to conventional practices. This report is a triple bottom-line assessment of the two most common micro-irrigation systems: sprinklers and drip tape. The following analysis is intended to aid in the selection and design of the rooftop irrigation system for the new SUB. Disclaimer: “UBC SEEDS provides students with the opportunity to share the findings of their studies, as well as their opinions, conclusions and recommendations with the UBC community. The reader should bear in mind that this is a student project/report and is not an official document of UBC. Furthermore readers should bear in mind that these reports may not reflect the current status of activities at UBC. We urge you to contact the research persons mentioned in a report or the SEEDS Coordinator about the current status of the subject matter of a project/report.”

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