Vertical Gardens

Evaluating Rooftop and Vertical Gardens as an Adaptation Strategy for Urban Areas

Brad Bass; Bas Baskaran

NRCC-46737

http://irc.nrc-cnrc.gc.ca/ircpubs

CCAF IMPACTS AND ADAPTATION PROGRESS REPORT APRIL 1, 1999 – MARCH 31, 2001 Project Number Project Title A020 Evaluating Rooftop and Vertical Gardens as an Adaptation Strategy for Urban Areas

Principle Investigators Brad BassAdaptation & Impacts Research Group Environment Canada

Bas Baskaran Institute for Research in Construction National Research Council

National Research Council Canada

Conseil national de recherches Canada

09/18/03

Evaluating Rooftop and Vertical Gardens as an Adaptation Strategy for Urban Areas

FINAL

Executive Summary Green roof infrastructure has become a multi-million dollarindustry in Germany and is gaining popularity in other European countries as well. Green roof infrastructure is more than just soil and plants on a roof, but consists of specialized membranes and drainage barriers to support the growing of vegetation on top of buildings. The benefits of this technology were researched and presented in the Canada Mortgage and Housing Corporation Report Greenbacks fromGreen Roofs (Peck at el., 1999). Many of the advantages of these technologies, such as the reduction of stormwater runoff, the reduction of cooling loads and the reduction of the urban heat island suggested that this technology could play a role in helping Canadian cities adapt to climate change. The goal of this research was to assess these benefits in a Canadian context. The report alsoinvestigated the potential of even a newer technology, vertical gardens, essentially moving the vegetation from the roof to the walls, in an urban environment. Vertical gardens could refer to vine-covered walls, but they could also include additional infrastructure components to support the growing of vegetation on a wall or as part of a window shade. Both technologies were assessed using observationsand modelling, and both were assessed with regards to the urban heat island and the reduction of indoor temperatures. The reduction of stormwater runoff was only evaluated for green roof infrastructure. The performance of green roof infrastructure was studied by field monitoring of an experimental field site, the Field Roofing Facility (FRF), at the National Research Council (NRC) campus inOttawa. The FRF consisted of two roof sections, a green roof and a modified bituminous roof that is representative of what is typically found on flat roofs in Canadian cities. The two roof sections were identical in principal components and differ only in the green roof components. The roofs were instrumented to measure temperature profile, heat flow, solar radiation and stormwater runoff. Theobservations were also used to comment upon membrane durability. The thermal performance was also simulated with Visual DOE and a hydrology model was constructed to simulate stormwater retention. The vertical gardens were tested on the roof of the Earth Science Building at the University of Toronto. The test consisted of comparing the surface temperature of the garden with the surface temperature of avertical wall and comparing shaded with unshaded temperatures. The thermal performance of the garden was also tested using Visual DOE. AutoCad and LightScape were used to illustrate how one prototype might be adapted to a real building.

CCAF Report B1046

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09/18/03

Evaluating Rooftop and Vertical Gardens as an Adaptation Strategy for Urban Areas

FINAL

The green roof was found toreduce the summer cooling load and the surface temperature of the roof. The Green Roof delayed runoff, reduced the rate and volume of runoff. These results corresponded with the simulation models. The vertical gardens were also shown to reduce summer cooling load, even more dramatically than the green roof. Both technologies reduced surface temperatures sufficiently to suggest that significant...