High Albedo Roof

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.

High albedo 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. In addition high albedo roofs can increase thermal comfort in non conditioned buildings. This implies that not only is cost of space heating increased but greenhouse gas production from combustion is driven up as well potentially exacerbating urban heat island effects. In this view those coatings are usually applied over flat and low sloped roofs in general in order to avoid summer overheating.

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. In the morning and in the late afternoon the high albedo materials were as cool as the air itself. 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. 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.

A sample cool roof this roof has a high albedo and reflects about 63 of the energy from sunlight. Cool roofs can be made of a highly reflective type of paint a sheet covering or highly reflective tiles or shingles. Area of roof meeting minimum sri roof 0 75 area of vegetated roof 0 5 total roof area. A cool roof is one that has been designed to reflect more sunlight and absorb less heat than a standard roof.

Over the past three decades high albedo roofing has been promoted as a strategy to mitigate the urban heat island effect and reduce cooling energy demand and costs. A high thermal emittance also plays a role particularly in climates that are warm and sunny. In los angeles the average roof albedo is about 0 17. 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.