Cool Roofs Help Reduce Energy Costs
Did you know? A cool roof can reduce air conditioning costs inside a building on a hot day and even cool down the air around the building, helping to reduce the heat island effect in your neighborhood.
What is a Cool Roof?
A cool roof is made of a material or has a coating that lowers the roof surface temperature, decreasing the amount of heat that passes into a home or commercial building. In general, traditional roofs absorb sunlight during the day, heating the building and the surrounding air. Roofs that are lighter in color or are reflective stay cooler than roofs that absorb sunlight. Keeping the roof cooler also helps cool down the air around the building. Cool roofs on buildings, along with more grass and trees planted nearby and more reflective materials used for pavement, mean the whole neighborhood could benefit by being a bit cooler on a hot day.
Benefits of Cool Roofs
Cool roofs have several benefits both for building owners and the environment:
- Keeping buildings cooler on hot days to improve indoor comfort and safety
- Reducing building air conditioning costs and reducing the strain on the electrical grid during peak energy demands
- Reducing the pollution and greenhouse gas (GHG) emissions associated with building energy use
- Decreasing roof temperature which can extend the life of the roof materials (slows degradation)
- Contributing to lower the temperatures in the surrounding air which helps reduce the urban heat island effect in cities. EPA has detailed information on how cool roofs can help communities reduce heat island impacts and risks at https://www.epa.gov/heatislands.
To get a bit more technical, a cool roof is one that has a high solar reflectance. A cool roof should also release or emit heat (infrared radiation) so it stays cool. Such a roof is said to have high thermal emittance. An ideal cool roof is a roof with both high solar reflectance (SR) and high thermal emittance (TE). While lighter color roofs tend to have the best SR and TE, new coating and material technologies now exist in other colors that have high SR and TE.
Types of Cool Roofs
Some common cool roof materials include membranes, shingles, coatings, stone/rock, metal, and tile across a variety of colors. Other cool roof strategies include ballasted roofing and green roofs. Learn more about cool roofs from the Cool Roof Rating Council (CRRC).
The CRRC maintains an extensive online database of roof products and their radiative performance ratings. Users can sort and search by product types, colors, performance parameters, manufacturers, and product names to find products that fit their building needs.
- Learn about Cool Roofs
- EPA Heat Island
- Lawrence Berkeley National Lab (LBNL) Heat Island Group
- Cool Roof Rating Council (CRRC)
Author: Doug Anderson, ENERGY STAR Certified Products