A cool roof on residential buildings is defined as one with a 3 year aged solar reflectance of at least 0 20 and an infrared emittance of at least 0 75 or minimum sri of 16 in climate zones 10 through 15 for steep slope applications greater than 2 12 and where the roofing product has a density less than 5 pounds per square foot.
Roofing with 3 years minimun reflectance.
Reflectance refers to the roofing material s ability to reflect the energy coming from the sun instead of absorbing it.
After 3 years the solar reflectance must be 0 15.
The requirements apply to new construction and to retrofits or additions that replace or re coat at least 2 000 ft 2 of roof space for nonresidential buildings and 1 000 ft 2 of roof space for.
The doe uses the low sloped cool roof definition from table 1 and defines steep sloped cool roofs as those with a 3 year aged sri of 29 or greater.
After 3 years the solar reflectance must be 0 50.
Effective january 1 2010 the standards will require that a cool roof material meet an aged solar reflectance value 3 year testing provided by the cool roof rating council crrc.
0 65 initial 0 50 aged.
These shingles must have an initial solar reflectance of at least 0 25 and a three year solar reflectance measurement of at least 0 15.
Steep slope roofs must have an initial solar reflectance of 0 25.
Innate reflectance is measured on a scale from 0 to 1 with the latter being the highest level of reflectivity meaning it reflects 100 of all radiant energy coming in contact with it.
If you re following iecc you have a couple of options for roof materials.
You can install one with a three year aged solar reflectance index sri of 64 or you can instead opt for one with an aged sri of 55 combined with an aged thermal emittance of 0 75 or.
Only those roof products that meet the specifications listed in either table 1 or table 2 below may qualify as energy star qualified.
Materials lacking 3 year aged tested values for either solar reflectance or thermal emittance shall be assigned both a 3 year aged solar reflectance in accordance with section c402 3 1 and a 3 year aged thermal emittance of 0 90.
Aged solar reflectance tested in accordance with astm c 1549 astm e 903 or astm e 1918 or crrc 1 standard.
The energy star program specifies minimum solar reflectance low slope.
