Staying Cool: The Green Roof Effect

Filed in archive Edge Technology on September 27, 2006

Studies show that the average temperature in urban areas is higher than communities situated in open, vegetation laden areas. Inside buildings, the relative temperature is warmer due to the effect of heat trapped within the building. Called the Heat island Effect, this phenomenon has been a serious consideration in building design.

The movement that encourages the use of Green Roofs started in Germany but with current issues such as global warming and energy efficiency, the environmental advantages of Green Roof Technology are brought to the center stage.

But are Green Roofs effective and if they are, how so?

In Toronto, it was observed that a growth of 10 centimeters of cover grass reduced the air conditioning needs of a one-storey building by 25%. There was also a notable 3 to 4 degree reduction in indoor air temperature (Celsius).

It appears that the growing plants on the roof of the building had created an insulating protection against yield. Plants transpire (lose water to the atmosphere though the microscopic holes). This barrier of heat exchange have reduced the heat exchange and have trapped air pockets which accounts for the cooling effect. No surprise now on why that building needed less cooling.

But researchers have also found out that if you distribute a number of roof areas within an urban community, the impact on heat island reduction is significant! I will have more on that tomorrow so stay tuned!