Energy Efficiency of Cool Roofs Measured
How do Cool Roofs Work?
Cool roofs have the ability to reflect sunlight and repel heat because the roofs are prepared, covered or coated with materials that have special characteristics. These are typically white roof and they reduce the heat island phenomenon, minimizing thermal impact on the microclimate and on the local environment. Modern cool roofs include highly reflective thermoplastic and liquid applied membrane and coating that provides a full range of benefits over a long service life.
Image depicts the energy flow of sunlight hitting a conventional flat roof (left) and a cool roof covered with a membrane or coating (right).
Efficiency of Cool Roofs
SOLAR REFLECTANCE (SR)
THERMAL EMITTANCE (IE)
SOLAR REFLECTANCE INDEX (SRI)
Cool Roofs Save Energy
Energy used to cool buildings in summer represents a major portion of overall energy consumption. It results in CO2 emissions, and this will increase as outdoor temperatures rise. Increased indoor temperatures in summer reduce general comfort and people’s productivity. Passive solutions like cool roofs can minimize heat gain inside buildings, improving indoor conditions and can be cost-effective in multiple ways.
Benefits of cool roofs for energy savings and reducing urban summer temperatures. The promotion of cool roofs to reduce cooling energy usage and peak-power demand of air-conditioned buildings. Solar reflectance is the most important characteristic of a roofing membrane to achieve the highest energy savings during warmer months.