Just as light-coloured clothing can help keep a person cool on a sunny day, cool roofs use solar-reflective surfaces to maintain lower roof temperatures. Highly reflective and light coloured roofs have now become an inclusive part of energy efficiency measure in a building. To achieve NZEB design goal, cool roofs can be used to reduce energy bills by decreasing air conditioning needs, improve indoor thermal comfort and decrease roof operating temperature. Traditional dark roofs reach temperatures of 66ºC (150ºF) or more in the summer sun, in contrast a cool roof under the same conditions could stay more than 28ºC (50°F) cooler.
Studies show that in warm and hot climates cool roofs perform well in meeting energy efficiency, cost-effectiveness,