Types of Cool Roofs
Cool roofs for commercial and industrial buildings fall into one of three categories: roofs made from inherently cool roofing materials, roofs made of materials that have been coated with a solar reflective coating, or green planted roofs.
Inherently cool roofs
White vinyl roofs, which are inherently reflective, achieve some of the highest reflectance and emittance measurements of which roofing materials are capable. A roof made of thermoplastic white vinyl, for example, can reflect 80 percent or more of the sun’s rays and emit at least 70% of the solar radiation that the building absorbs. An asphalt roof only reflects between 6 and 26% of solar radiation, resulting in greater heat transfer to the building interior and greater demand for air conditioning.
Coated roofs
An existing (or new) roof can be made reflective by applying a solar reflective coating to its surface. The reflectivity and emissivity ratings for over 1000 reflective roof products can be found in the CRRC (Cool Roofs Rating Council) website.
Green roofs
Green roofs provide a thermal mass layer which helps reducing the flow of heat into a building. The solar reflectance of green roofs varies depending on the plant types (generally 0.3-0.5). Because of the lower solar reflectance, green roofs reflect less sunlight and absorb more solar heat than white roofs. The absorbed heat in the green roofs is trapped by the greenhouse effect and then cooled by evapotranspiration.
Read more about this topic: Cool Roof
Famous quotes containing the words types of, types, cool and/or roofs:
“Science is intimately integrated with the whole social structure and cultural tradition. They mutually support one other—only in certain types of society can science flourish, and conversely without a continuous and healthy development and application of science such a society cannot function properly.”
—Talcott Parsons (1902–1979)
“The American man is a very simple and cheap mechanism. The American woman I find a complicated and expensive one. Contrasts of feminine types are possible. I am not absolutely sure that there is more than one American man.”
—Henry Brooks Adams (1838–1918)
“Then, the cool kindliness of sheets, that soon
Smooth away trouble; and the rough male kiss
Of blankets; grainy wood; live hair that is
Shining and free; blue-massing clouds; the keen
Unpassioned beauty of a great machine;”
—Rupert Brooke (1887–1915)
“The frost was on the village roofs as white as ocean foam;
The good red fires were burning bright in every ‘longshore home;
The windows sparkled clear, and the chimneys volleyed out;
And I vow we sniffed the victuals as the vessel went about.”
—Robert Louis Stevenson (1850–1894)