A Guide for Hotels: Boosting Profits with Energy Efficiency & Conservation
Building Envelope: Cool Roofs
Cool roofs are roofs with special coatings or surfaces that reflect heat. While this seems simple in concept, the cooling benefits can be quite dramatic. Consider that dark surfaces in the sun are up to 70ºF hotter than white ones - this means that when normal rooftop temperatures are peaking at 190ºF during the hot summer months, cool roofs only reach about 120ºF. The ability of your rooftop to reflect solar radiation and reduce surface temperatures is related to the effort your cooling equipment exerts to condition indoor spaces.
Besides lowering HVAC operating costs, cool roofs help others in the local community. In cities, building rooftops and paved surfaces collectively create urban heat islands. Researchers at Lawrence Berkeley National Laboratory and the U.S. EPA have found that these heat islands raise outdoor temperatures 6ºF to 8ºF above surrounding areas, which can lead to a higher incidence of smog.
Cool roofs make sense when:
- A building has high air conditioning loads and/or is located in a hot, sunny climate.
- The roof has a large surface area as compared to the overall building size.
- Re-roofing or other roof maintenance is scheduled as part of routine operations and maintenance.
- Constructing a new building.
- Installation is part of a wider effort to reduce cooling loads; cool roofs and good insulation levels go hand in hand.
Cool roofs are most effective during the hottest part of the day and the hottest time of year, coinciding with peak energy demand. Having a cool roof allows for lower air conditioning settings, reduced energy costs and reduced strain on California's power grid - all without sacrificing guest or employee comfort.
Remember that a cool roof is only one surface, and that any rooftop retrofit should be part of a wider effort to improve insulation of the 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.