Green Roofs protect a building and save cooling energy relative to four factors: 1) soil moisture content,
2) soil depth, 2) plant coverage and 4) plant health.
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Conclusions:
1) G-SKY Extensive Green Roof normalize the temperature
of the buildings roof and membrane, resulting in an stress reduction on the building and building materials.
2) Heat transfer through the building is normalized and reduced. Cooling
load is reduced 0.052 kWh/ft2 (0.56 kWh/m2) at 100% peak air conditioner usage.
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Conclusions:
Exposed Membranes: Exposed membranes surface temperature reaches
as high as 58°C on a hot day. The membrane temperature is extremely volatile
and fluctuates as much as 40°C. The room temperature below an exposed membrane
fluctuates as much as 21°C requiring a huge cooling load to make the building comfortable
for inhabitants.
Irrigated Green Roofs: Irrigated Green Roofs reduce roof surface
temperatures to 28°C (Sky Garden) and 33°C (G-SKY). The temperature at the
membrane is normalized and fluctuates only 2°C (Sky Garden) and 4.5°C (G-SKY)
over a 24 hour period. The inside room temperatures are reduced by as much
as 15°C (Sky Garden) and (G-SKY) 9°C. Reduced heat being drawn into the building
through the roof membrane results in a significant reduction in cooling energy requirements.
By normalizing the temperature of the roof membrane, its viable service life is
significantly extended.
Non-irrigated Green Roofs: Comparatively, non-irrigated Green Roofs are far less effective than irrigated Green Roofs. Non-irrigated Green
Roofs reduce roof surface temperatures to 38°C (Sky Garden) and 41°C (G-SKY).
The temperature at the membrane is not normalized and fluctuates 9.5°C (Sky
Garden) and 12°C (G-SKY) over a 24 hour period. The inside room temperatures
are reduced only 6~7°C (Sky Garden) and (G-SKY) 1~2°C. Since very little heat
is reduced from being drawn into the building through the roof membrane, very little
reduction in cooling energy requirements are realized. The slight temperature
reduction in the roof membrane
may extend its viable service life.
For more information on Thermal Insulation research, how it works and an example
of how to calculate your energy savings, please visit the
Benefits - Energy Savings page.
In the over 35 years of modern Green Roof research, there have been literally hundred
similar experiments done throughout the world (Germany, Italy, France, China,
Singapore, Taiwan, Japan, Korea, Sweden, Canada and the United States) that have
all resulted in similar conclusions to those in the experiments above. In fact, there are several dozen research facilities
in the world that have live monitoring systems that continue to expose these facts, listed below
are just a few of the many Green
Roof research facilities around the world.
Environmental Building Research and Educational Facility, Japan, Live Green Roof Monitoring System |
Yokohama City Hall Public Garden and Live Monitoring System. |
Osaka Environmental, Agricultural and Forestry Industries Department Green Roof
Research Center with Remote Live Monitoring. |
Roppongi Hills Complex, Rice Field on a Roof. Educational facility to demonstrate
how time-honoured traditions can help to fight a modern-day problem (the Heat Island problem). |
Taipei Environmental Building Research Facility,
Taiwan |
Shanghai University, Green Building Research, Department of Engineering |
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