Energy Efficiency Delivered by “Cool Roof” Reflectivity
A high-performance roof can be a powerful asset in reducing energy consumption and improving long-term energy efficiency. When used with appropriate insulation on low-sloped or flat roofs, a high-reflectivity, high-emissivity Duro-Last Cool Zone system can:
- Reduce building energy consumption by up to 40 percent
- Improve insulation performance to reduce winter heat loss and summer heat gain
- Preserve the efficiency of rooftop air conditioning
- Potentially reduce HVAC capacity requirements
- Decrease the effects of Urban Heat Islands and related urban air pollution
The Duro-Last Cool Zone roofing system exceeds “cool roofing” standards established by these organizations:
The EPA’s ENERGY STAR Roof Products Program has established a minimum standard that requires low-slope roof products to have an initial reflectance of at least 65 percent, and a reflectance of at least 50 percent after three years of weathering. If there is any doubt about whether a roofing system is “cool” or energy efficient, check to see if it is listed in the ENERGY STAR Roof Products listings www.energystar.gov. Use their online calculator to determine potential energy savings for your building.
The Cool Roof Rating Council (CRRC) is a non-profit association that implements and promotes fair, accurate performance ratings for solar reflectance and emittance from roof surfaces. All tests for measuring cool roof properties are performed by accredited, independent laboratories following established ASTM International protocols. Performance data for products from numerous manufacturers can be found on the CRRC’s web site, www.coolroofs.org.
Title 24 of California’s Energy Efficiency Standards for Residential and Nonresidential Buildings is a wide-ranging “green” construction bill that became effective in October, 2005. Title 24 specifies that new and replacement commercial roofs virtually any low-slope roofing project that requires a construction permit must have a minimum initial thermal emittance of 75 percent, and a minimum initial solar reflectance of 70 percent, as rated by the Cool Roof Rating Council (http://www.energy.ca.gov/title24/).
Other Energy Considerations
The American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) established Standard 90.1 as a minimum requirement for energy-efficient building design. President Bush has signed legislation offering tax deductions to buildings that exceed the 90.1 Standard.
Lawrence Berkeley National Laboratory recently determined that increasing the R-value of a roofing system in Los Angeles from R-9 to R-15 would reduce annual energy costs by $2,500 and lower carbon dioxide emissions by thousands of pounds.
Executive Order 13123, now known as Federal Acquisition Regulation Case 1999-011, mandates that federal office buildings must reduce energy usage 30% by 2005, and 35% by 2010. It also mandates that federal industrial buildings and laboratories must reduce energy consumption 20% by 2005, and 25% by 2010. Federal agencies also must use ENERGY STAR products when available, and decisions must be based on energy and life-cycle cost analyses.
In cooperation with state and local governments, many utility companies offer rebates for using reflective roofing systems. These rebate programs are offered nationwide, not just in southern climates. For instance, Excel Power, the fourth largest utility company in the United States, has awarded rebates as far north as Minnesota.
Energy efficiency also reduces pollution by mitigating the urban heat island effect (see http://eandE.LBL.gov/heatisland).