green roof is dependent on climate, energy
costs, location, and building and mechanical design. It is also dependent on the
building's shape (i.e. the impact of a
10, 000-square-foot green roof on a
10-story building compared to a two-story
building). The amount of energy to cool or
heat the building can be affected by the
temperature of the air intake, specifically
rooftop equipment. The green roof can
provide a more stable environment on the
roof; one that is cooler when it is hot and
warmer when it is cold, which can reduce
cooling and heating requirements. In addition, the potential energy savings from the
green roof may help achieve carbon credits
if available.
Biodiversity benefits
Biodiversity is very difficult to measure
economically but its value is generally created by adding biodiversity back into
dense urban regions. Organizations and
governments have designed schemes to
value biodiversity financially by creating
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credit systems or banking systems — the
BushBroker scheme and the biodiversity
banking system (BioBanking) for example.
In addition, there is potential economic
value to bee farms and nearby agriculture
with a green roof having the potential to
attract bees to pollinate plants.
typically not observed on roofs with threeor six-inch growth medium.
Acoustical benefits
Buildings below highways or highair-traffic areas can receive benefit from a
green roof through noise mitigation. However, the benefit may be limited to green
roofs under these conditions.
Heat island benefits
The indirect effect of the ability for
green roofs to mitigate the heat island effect is substantial. Reducing heat island has
a societal affect that can reduce average
and peak temperatures, air pollution, and
heat/pollution related illness. The addition
of green roofs, specifically at a citywide
level can have an economic benefit — the
reduction in daily and peak temperatures
as a result of reducing the temperatures of
the surroundings.
Clean air benefits
Green roofs may help to mitigate air
pollution. The absorption, temperature
cooling and sequestration ability of the
green roof can potentially offset air treatment systems for NOx, SOx, PM and
CO2. In addition, at the city scale, the
green roofs cooling ability (see Heat island
benefits) potentially even further offset
NOx and Ozone.
Agricultural benefits
Agricultural services such as food, biofuel and nursery growth could generate
benefits from green roofs, though they are
Aesthetics and quality-of-life benefits
Productivity increase and reduction in
absenteeism due to green roofs is difficult
to quantify for building tenants, though
Landscape and Irrigation 9
