Addressing the Water–Energy–Food Nexus through Enhanced Green Roof Performance

Abstract

Urban densification and climate change are creating a multitude of issues for cities around the globe. Contributing factors include increased impervious surfaces that result in poor stormwater management, rising urban temperatures, poor air quality, and a lack of available green space. In the context of volatile weather, there are growing concerns regarding the effects of increased intense rainfalls and how they affect highly populated areas. Green roofs are becoming a stormwater management tool, occupying a growing area of urban roof space in many developed cities. In addition to the water-centric approach to the implementation of green roofs, these systems offer a multitude of benefits across the urban water–energy–food nexus. This paper provides insight to green roof systems available that can be utilized as tools to mitigate the effects of climate change in urbanized areas. A new array of green roof testing modules is presented along with research methods employed to address current issues related to food, energy and water performance optimization. Rainwater runoff after three rain events was observed to be reduced commensurate with the presence of a blue roof retention membrane in the testbed, the growing media depth and type, as well as the productive nature of the plants in the testbed. Preliminary observations indicate that more productive green roof systems may have increasingly positive benefits across the water–energy–food nexus in dense urban areas that are vulnerable to climate disruption.

Evapotranspiration Rates of Representative Green Roof Systems and the Implications for Green Roof Policies

“…Each system (food, energy, and water) has multiple linkages to one another. The relationship of how these crucial domains interact is often described in nexuses (Wright, Lyte, Santillo, Marcos, & Valter Mai, 2021). The water energy nexus is the relationship between how much water is used to transmit energy as well as the amount of energy it takes to collect, transport, clean and dispose of water (Rasul & Sharma, 2016).…”

“…Each of the test beds utilizes GR growing media that follows the FLL guidelines, including a porosity of 60% and an averaged density of 850 kg/m 3 (Ono, et al, 2005). This is to establish evapotranspiration and retention rates that can be correlated to multiple GR systems that are currently being sold in the marketplace (Wright, Lytle, Santillo, Marcos, & Valter Mai, 2021).…”

Detection of Green Roofs through Satellite Imagery Using Faster R-CNN

“…For example, green roofs can help reduce food insecurity in urbanized areas by providing a local food source, reduce water require energy consumption and with a smart system, can help reduce water consumption [35]. Wright, Lytle, Santillo, Marcos and Mai [35] analyzed the Water-Energy-Food Nexus of Green roofs. Green roof testbeds were built, based on past studies [36]- [39], and monitored rainwater runoff, crop yield and energy.…”

A pathway to rooftops: a feasibility study of green roof typologies at 105 Bond Street

“…The City of Toronto is one of North America's leaders in green roof design and implementation. In 2006, following a study commissioned by the City and produced by a Ryerson University team, Toronto adopted its inaugural Green Roof Strategy (Wright, Lytle, Santillo, Marcos, & Mai, 2021). During its first two years the program would result in 30 green roofs being approved via the planning process (City of Toronto, 2021).…”