DK Haney Roofing is an Energy Star rated contractor. Energy Star is a government-backed program helping businesses and individuals protect the environment through superior energy efficiency. To earn the Energy Star label, we are proud to install products that are generally 30% more efficient than if they were built strictly to code.
For a more detailed analysis of your potential energy savings, go to the ENERGY STAR Roofing Comparison Calculator.
Energy efficient programs, rebates and grants are currently offered for schools, government, non-profit, commercial, and industrial businesses. DK Haney Roofing works with these programs to find the best fit for your business and potentially save you thousands.
LEED is the US Green Building Council's (USGBC's) effort to provide national standards for what constitutes a "green building."
- An upfront investment of 2% in green building design, on average, results in life cycle savings of 20% of the total construction costs - more than ten times the initial investment. (Kats, G. (2003). The Costs and Financial Benefits of Green Buildings: A Report to California's Sustainable Building Task Force.)
- Estimated value of green commercial construction starts:
- 2001: $3.24 billion
- 2000: $792 million
- 2002 $3.81 billion
- 2003: $5.76 billion
- 2004: $4.51 billion
- 2009: $12 billion
- 2010 (projected): $60 billion (10% construction starts)
Find out more at U.S. Green Building Council.
The two most important factors in achieving a cool roof are Reflectivity and Emissivity.
Reflectivity is one key measurement of energy performance when evaluating for a cool roof. Reflectivity is the percentage of the sun's energy that is reflected by a surface. For example, the Duro-Last Cool Zone roofing system has an initial reflectivity of 87.5% and a three-year weathered reflectivity of 86.5%, based on Energy Star testing procedures. In essence, 12.5% of the sun's energy is retained in a Duro-Last roof, while the other 87.5% is immediately reflected back into the atmosphere. An average Black EPDM roof has an initial reflectivity of 6%, indicating that 94% of the sun's energy is retained in the Black EPDM roof.
Most authorities have concentrated on reflectivity as the prime measurement of energy performance of cool roofing. However, with even the most reflective materials, some energy is absorbed, and if that absorbed energy is not released efficiently, it can cause a roof to heat up. Because of this, emissivity should also be considered.
Emissivity is the second key measurement of energy performance when evaluating for a cool roof. Emissivity is a measure of power indicating how effectively/quickly a surface releases the originally retained sun's energy. Scientists use a number between 0 and 1, or between 0% and 100%, to express emissivity. The lower the number or percent, the slower the material is to release the heat. With the exception of a metallic surface, most roofing materials can have emissivity values above 0.85 (85%).
The Duro-Last Cool Zone roofing system has an emissivity of 95%. So the originally retained sun's energy (12.5%) in a Duro-Last Cool Zone roof is released at a 95% rate.
SRI Another measurement, called the solar reflectance index (SRI), is beginning arise as a cohesive measure. SRI combines reflectivity and emissivity to measure a roof's overall ability to reject solar heat. The calculation of this index is defined by ASTM E 1980-01 and is based on a mathematical formula that includes values for solar absorbance, solar flux, thermal emissivity, the Stefan Boltzman constant, and various other coefficients.
Standard black (reflectivity 5%, emissivity 90%) has an index of 0.
Standard white (reflectivity 80%, emittance 90%) has an index of 100.
Very hot materials can actually have negative values and very cool materials can have values greater than 100. See some samples below to see the correlation of factors:
| Roofing System Duro-Last Roof White EPDM Kynar Coated Metal, White New, Bare Galvanized Steel Light Gravel on BUR White Granular Surface Bitumen Dark Gravel on BUR Black EPDM |
SRI 108 84 82 46 37 28 9 -1 |
Reflectivity 87.5% 69% 67% 61% 34% 26% 12% 6% |
Emissivity 95% 87% 85% 4% 90% 92% 90% 86% |
