Low Slope Cool Roof Treatment Sri

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.

Low slope cool roof treatment sri.

Commercial cool roof options include bright white membranes and white coatings. Low slope roofs require an initial sr value of 0 65 or higher and 0 50 or greater after three year. There are different cool roof standards for commercial low slope roofs and residential steep slope roofs. Alternatively you can apply cool reflective coatings.

3 yr aged solar reflectance min. Painting a metal roof can increase its solar reflectance and thermal emittance allowing it to achieve cool roof status. Emissivity is a material s ability to release absorbed energy. How they can be made cool.

Wrapping it all up. 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. 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. Roof area covered by building integrated photovoltaic panels and solar thermal panels.

Department of energy doe has decided to implement cool roofs on all its buildings whenever practicable3. Minimum solar reflectance index value by roof slope. If aged sri is not available the roofing material shall have an initial sri equal to or greater than the values in table 1. Use roofing materials that have an sri equal to or greater than the values in table 1.

Sri low slope1 13 15 0 63 0 75 75 steep slope1 10 thru 15 0 20 0 75 16 1 low slope rise to run ratio of 2 12 lower than 9 5 degrees steep slope rise to run ratio 2 12 9 5 degrees or more table 1 residential cool roof. Low slope roof less than 2 12 slope check applicable box below. Or this sri value roof slope climate zone min. 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.

Cool roof requirements for residential and non residential now apply to low slope and steep slope roofs. Residential roofing options include asphalt shingles metal clay tiles and concrete tiles. Minimum sri values of 78 and 29 for low and steep sloped cool roofs respectivelyiii. Unpainted metals are typically good solar reflectors but poor thermal emitters so they rarely satisfy low slope cool roof requirements.