The Need for COOL Roofs for Sustainable Solution
Sustainble building design and energy efficient living leads to environmentally responsible economic growth. Cool Roofs offer us one of our most simple and effective Global Warming mitigation strategies.
Roof surfaces represent 20-25% of the built environ and act as "Solar Radiators" so much so that around 93% of a building's HEAT GAIN can be attributed to radiant energy (meaning the sun's rays converted to heat after absorption). In Australia, where the prominent source of a buildings heat gain is Radiant Sunlight and up to 93% of a buildings heat gain in summer is attributable to radiant heat. Reflective COOL Roofs should be a key focus in combating heat gain, reducing energy cost and its greenhouse emissions.
"Urban Heat Island Effect"
The term 'Urban Heat Island' refers to the fact that cities and urban areas are often significantly warmer than the rural areas that surround them. The 'Urban Heat Island' phenomenon was first investigated in the 1810's when it was discovered that the air surface temperatures in London were often higher than i nthe surrounding rural areas. The United States Environmental Protection Agency now reports that on average US cities are up to 5.6°C warmer than the surrounding rural areas.
There are several causes of the 'Urban Heat Island' :
- Increased absorption and retention of heat due to decreased surface reflectivity
- Changes in the thermal properties of surface materials
- Reduced evapotranspiration due to decreased vegetation cover
Of various mitigation strategies, Cool Roofs offer the simplest and cheapest approach to stabilising global warming - reducing CO2 emissions and paying for itself in direct energy savings.