Low Slope Cool Roof Treatment Sri

Install compliant cool roof material that is listed in the cool roof rating council crrc rated product directory 0 63 aged solar reflectance 0 75 thermal emittance or an sri of 75.

Low slope cool roof treatment sri.

Low slope roofs face the sun on a more consistent and extended period of time than steep slope roofs because they re flatter which is why the reflectance and sri values must be higher to withstand the longer duration of heat from the sun. Painting a metal roof can increase its solar reflectance and thermal emittance allowing it to achieve cool roof status. Low slope roof less than 2 12 slope check applicable box below. In addition the common belief that an average r value is just as good as the code requirements is just that a common belief not a fact.

If aged sri is not available the roofing material shall have an initial sri equal to or greater than the values in table 1. There are different cool roof standards for commercial low slope roofs and residential steep slope roofs. Commercial cool roof options include bright white membranes and white coatings. Or this sri value roof slope climate zone min.

Cool roof requirements for residential and non residential now apply to low slope and steep slope roofs. Wrapping it all up. Use roofing materials that have an sri equal to or greater than the values in table 1. How they can be made cool.

3 yr aged solar reflectance min. Roof area covered by building integrated photovoltaic panels and solar thermal panels. Unpainted metals are typically good solar reflectors but poor thermal emitters so they rarely satisfy low slope cool roof requirements. Emissivity is a material s ability to release absorbed energy.

The ages solar reflectance and thermal emittance requirements will vary depending on the slope of the roof climate zone and the density of the roofing product. Department of energy doe has decided to implement cool roofs on all its buildings whenever practicable3. The solar reflectance index is used for compliance with leed requirements and is calculated according to astm e 1980 using values for reflectance and emissivity. Minimum sri values of 78 and 29 for low and steep sloped cool roofs respectivelyiii.

Tapered insulation is the most common method for creating a slope on a low slope roof but frustratingly neither code addresses compliance for tapered systems. Minimum solar reflectance index value by roof slope. Residential roofing options include asphalt shingles metal clay tiles and concrete tiles. Low slope roofs require an initial sr value of 0 65 or higher and 0 50 or greater after three year.