High Albedo Roof

As one would expect albedo roofs are formulated with special high eminence materials that keep project a high level of thermal energy back into the atmosphere.

High albedo roof.

A sample cool roof this roof has a high albedo and reflects about 63 of the energy from sunlight. A high thermal emittance also plays a role particularly in climates that are warm and sunny. The specification of a high albedo roof may result in a requirement for added heating which otherwise would have been gathered passively through the roof. A high solar reflectance or albedo is the most important characteristic of a cool roof as it helps to reflect sunlight and heat away from a building reducing roof temperatures.

Cool roofs can be made of a highly reflective type of paint a sheet covering or highly reflective tiles or shingles. In los angeles the average roof albedo is about 0 17. In this view those coatings are usually applied over flat and low sloped roofs in general in order to avoid summer overheating. A cool roof is one that has been designed to reflect more sunlight and absorb less heat than a standard roof.

By preventing a majority of the heat from ever reaching the surface these roofs work to greatly reduce hvac cooling costs during the summer months. This criterion can also be met by installing a vegetated roof for at least 50 of the roof area or installing a high albedo and vegetated roof in combination that meets this formula. Nearly any type of building can benefit from a cool roof but consider the climate and other factors before deciding. On clear sunny days when the solar noon surface temperatures of conventional roofing materials were about 40 degrees c 72 degrees f warmer than air the surface temperature of high albedo coatings were only about 5degreesc warmer than air.

In the morning and in the late afternoon the high albedo materials were as cool as the air itself. Area of roof meeting minimum sri roof 0 75 area of vegetated roof 0 5 total roof area. On a sunny day a roof that strongly reflects sunlight can stay much cooler than a roof that absorbs sunlight. High albedo coatings as previously mentioned are able to limit the increase of surface temperature of a roof in opposition to a high absorptive finishing.