| A Green
Roof is a roof of a building which is partially or completely covered with
plants. It may be a tended roof garden or a more self-maintaining ecology
like a living wall or breathing wall. Here are some of the benefits
of green roofs:
1. Dramatic
Economic Gain / Energy Saving Properties
- The green roof
reduced 95% of the heat gain and 26%
of the heat loss. A reduction from 6.0-7.5 kWh/day corresponds to a 75%
reduction and the potential for savings.
- Adds 10% R
Value insulating properties
- Almost double
the roof life expectancy
- Less strain on
HVAC and other mechanical systems resulting in decreased service and
increased life expectancy
- Possible tax
reliefs avaiable
- Dramatically
improves building performance
- Doubles the
lifespan of the existing roof
- Reduces noise
levels
- Increases
living space
2. Reduce
Storm Water Runoff! Cleaner Rivers? No beach closings?
Sormwater
runoff is water from rain or melting snow that does not soak into the
ground but runs off into waterways. As stormwater flows toward the
nearest waterway, it collects and transports pollutants. Common
pollutants associated with stormwater runoff include sediment, animal
waste, salt, pesticides, fertilizers, and automotive fluids. Stormwater
is a major contributor to many widespread water quality problems
including nuisance algae blooms, beach closures, and the loss of fish
and wildlife habitat.
- The ability for
the roof to aid in Storm water retention, by slowing the flow off the
roof during a storm event.
- In a Green Roof Cycle
30% of the water is used by plants, 30% percolates to aquifers, 40%
returned to the atmosphere therefore Little to no surface runoff. Over
time this cycle will greatly improve our local water quality.
- In a
Metropolitan/Urban Cycle (Non Green-Roof) 5% to goes to aquifers, 15%
to the atmosphere and 75% to surface runoff
3.
Improved Air Quality
- Gaseous
pollutants are absorbed through photosynthesis and airborne
particulate matter is trapped in the leaves.
- Gas exchange by
the plants helps to add oxygen to the air therefore helping to reduce
smog.
- Rooftop
microclimate is produced with cooler air due to transpiration of the
plants therefore reducing the cost of the air transfer hot to cool
in air conditioning = less expensive air conditioning. Less air
conditioning means less electricity consumption which means less power
generation from nuclear and fossil fuel burning plants which improves
air quality further
- Green roofs cool
the ambient air temperature (reduce the Urban Heat Island Effect) in
cities which means less smog days.
- Studies have
shown that 1500 sq f of plant surface area produces enough oxygen
for one person for 24 hours.
- Cleaner air is a
direct benefit to asthma sufferers the elderly and young who are
limited to indoor activities on " Bad Air" days
4. Urban
Heat Island Effect and Temperature Regulation
Green
roofs help address the Urban Heat Island Effect which is the phenomenon of
thermal gradient differences between developed and undeveloped areas. Most
of the sun's energy is re-radiated as heat. Planted areas only reflect 20%
of the sun's energy.
- Green
roofs insulate buildings by external shading, cool industrial
buildings and create microclimates, which can alter the climate of a
city as a whole.
- The
difference between urban and suburban heat index can range to a 15
degree difference.
5.
Ecological and Habitat Forming
- Possibilities for
habitat preservation and protection of flora and fauna.
- Replaces land
taken by buildings and thereby contributes to preserving biological
diversity.
- Beautifies
otherwise barren eyesores of our cityscape and provide unique
opportunities for design and creativity.
- Increased urban
habitat for song birds and butterflies.
- Health and
horticultural therapy applications.
- Movement, colour,
sound and texture of plants add to the overall health and well being
of citizens.
- The community
overall will also benefit from the environmental improvements
mentioned above.
Sited from
the:Ryerson
University, Quantitative Findings Oct. 2005, Report on the
Environmental Benefits and Costs of Green Roofing
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