09/18/03
Evaluating Rooftop and Vertical Gardens as an Adaptation Strategy for Urban Areas
FINAL
closer to or above 30% in Vancouver or St. Johns. The savings from a green roof were similar across all of the cities, with slightly higher savings being achieved in Montreal and Vancouver. The DOE software does not provide for the inclusion of evaporative cooling, which would reduce energy even further. For example, simulations of the impact of cooling rooftop temperatures with white roofs indicated that electricity consumption for air conditioning could be reduced between 6-18% in California. The simulations were run for a wide range of buildings in different locations, which accounts for the variation in results. Other studies in the United States indicated savings of 20-30% from shading or evaporative cooling, but they did not account for the use of machinery and other activities. Although this modelling work is incomplete, in that it did not include evaporative cooling, due to the limitations of the model, it is still possible to obtain modest savings solely due to the insulation and shading of green roofs, even on a multistory building. During the winter, the savings on heating are slightly larger due to the additional insulation. Although the need for heating may decline in Toronto, it still accounts for the largest share of energy consumption in residential and commercial buildings. In buildings without insulation, these savings are even greater. However, significant reductions in air conditioning are possible with vertical gardens, solely due to shading the windows. The energy savings from both technologies would increase if evaporative cooling can be factored into the simulation.
CCAF Report B1046
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