Manufacturers Best Practice Guide

Cool Roofs

Industrial and manufacturing facilities are ideally suited for a building upgrade that can reduce indoor temperatures during the hot summer months: cool roofs. Cool roofs are made of, or coated with, materials that reflect solar radiation. The use of cool roofs on industrial flat or low-sloped roofs can save 20% to 70% of annual cooling costs. Consider that dark surfaces in the sun are up to 70ºF hotter than white ones - so when normal rooftop temperatures are peaking at 190ºF during the hot summer months, cool roofs only reach about 120ºF.

The new standards set by the 2005 Title 24 update required that cool roofs be used in new construction and the re-roofing of non-residential facilities. While most cool roofs have consisted of white reflective materials, a wider color range is increasingly available for sloped applications. Currently cool roofs come in the forms of: shingles, coatings, membranes, metal and tile.


This simple concept of reflective roofing can yield significant benefits.

  • Reduce peak energy demand
  • Reduce building heat absorption, thus reducing air conditioning use and subsequent costs
  • Increase employee comfort
  • Increase air quality
  • Reduce greenhouse gas emissions
  • Extend life of roof materials; roofs can be periodically cleaned as well as recoated
  • .
  • Extend fire resistance
  • Reduce local "heat island" effect
  • Meet Title 24 building standards


Cool roofs can be installed regardless of whether an HVAC system is used, and work passively to block solar heat before it enters a building. Most effective during the hottest part of the day and the hottest time of year, the benefits of cool roofs coincide with peak energy demand. In buildings that also have HVAC or refrigeration, cool roofs help lower energy costs when they are most expensive.

Besides lowering indoor temperatures, cool roofs help others in the local community. Dark rooftops, the removal of trees and the incidence of large paved surfaces collectively create urban heat islands. Heat islands are a phenomenon in which cities can be 2 to 8 degrees warmer than surrounding areas due to buildings and paving absorbing heat from the sun and releasing the heat at night. The elevated temperatures cause an increased demand for air conditioning in homes, buildings and vehicles, resulting in increased levels of smog, increased energy usage and increased costs.

The EPA estimates that the nation spends $40 billion annually to air condition homes and buildings. That amount represents one-sixth of all the electricity produced annually, so widespread use of cool roofs could have a dramatic impact.

The installation of a cool roof should be a part of a larger plan for the building envelope as well as internal systems. The efficiency of HVAC, lighting and energy management systems are directly related to the heat absorption of a building's roof. Be sure to consider cool roofs as an integral part of a larger energy management plan.

Remember that the roof is only one surface, and any rooftop retrofit should be part of a wider effort to improve the overall building envelope. Installing proper levels of insulation provides year round benefits by preventing heat gain in the summer and blocking cold air infiltration in the winter. Also, consider painting south-facing and west-facing walls a white or light color that reflects solar radiation.

In light of Title 24 building requirements cool roofs are receiving increased attention from research institutes, and the technology is rapidly improving. Be sure to check on the latest developments before making your installation plans.

For more information, consult Flex Your Power's cool roof product guide.

New Technology: Heat Island Group, Lawrence Berkeley National Laboratory

Lawrence Berkeley National Laboratory (LBNL) has developed innovative cool roofing materials with solar reflecting pigments that will cut energy consumption in warm climates by 10% to 20%. This technology is innovative because it is not simply a reflective light color; it is an improvement to the reflectivity of dark-colored roof materials, which are preferred by U.S. consumers. This allows cool roof benefits to be integrated into all types of popular roofing materials. LBNL is working with a number of California companies to advance these technologies, and if California was to adopt them under title 24, it could save 65 GWh of electricity per year. For their work on cool roofs the Heat Island Group received a Flex Your Power Award for innovative products and services.