The roof is the perfect place to start your energy conservation strategy
One of the most effective ways to cool a building is to redirect solar energy before it raises temperatures inside the building.
Q: How much money can I save with a cool roof?
California Energy Commission:
"The California Energy Commission has concluded reflective roofs can reduce a building's energy use by 20% and save consumers money."
Environmental Protection Agency (EPA):
"A California study found that cool roofs provide an average yearly net savings of almost 50 cents per square foot."
Energy represents 30% of a typical office building's costs - the single largest operating expense.
Source: www.epa.gov/climateleaders - Data based on 2002 BOMA Experience Exchange Report
- Increases occupant comfort
- Lowers internal building temperatures
- Less energy required to cool the building
- Reduces wear and increased effectiveness of HVAC equipment
Q: What is a cool roof?
Cool roofs are highly reflective and emissive materials that stay 50 to 60 degrees F cooler in the summer sun, thereby reducing energy costs, improving occupant comfort, cutting maintenance costs, increasing the life cycle of the roof, and contributing to the reduction of urban heat islands and associated smog.
Q: Will cool roofs significantly increase my heating bills in the winter months?
No. The roof is an insignificant source for heat gain in winter. While cool roof owners may pay slightly more to heat their homes, this amount is usually insignificant compared to the cooling energy savings during the summer.
The proof behind the claim:
- In the wintertime, the sun is much lower in the sky and less intense. (Passive solar heating usually occurs from sunshine streaming through windows this time of year.)
- There is a higher incidence of cloudy days, and in some regions, the roof is covered in snow for long periods.
- Winter days are shorter (fewer hours of sunshine).
- A cool roof will not shed more heat proportionate to other types of roofing materials at night or on cloudy days. It will simply limit the amount of heat entering the building on hot summer days.
Q: What are solar reflectance and thermal emittance?
Solar reflectance and thermal emittance are the two radiative properties used to measure the "coolness" of a roof.
High Solar Reflectance + High Thermal Emittance = Less Energy $$$ Required
Q: How cool is a cool roof?
During the summer, a typical dark roof is 150° to 190°F at peak, while cool roofs peak at 100° to 120°F.
Q: What specifications does a roof need to meet to be considered for credit under the Title 24 Standards?
Commercial and residential products must meet the following specifications according to the ASTM standards outlined below:
ENERGY STAR® approved
ENERGY STAR® is the trusted, government-backed symbol for energy efficiency. In order to qualify, low-slope roof products must have an initial solar reflectance of at least 65%. After 3 years, the solar reflectance must be at least 50%.
CA Title 24 approved
The California Title 24 Building Code defines a "cool roof" as having a minimum solar reflectance of 70% and minimum thermal emittance.
The Cool Roof Rating Council® (CRRC) is an independent, non-profit organization that maintains a third-party rating system for radiative properties of roof surfacing materials.