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NC-2009 SSc7.2:Heat Island Effect—Roof

Is compliant SRI paint enough?

Hello, We were under the impression that painting 100% of our roof areas with SRI tested compliant paint in accordance with the manufacturer technical instructions would meet the requirements of credit SSc7.2 to secure the LEED point. However, the USGBC reviewer had made the following comment on this strategy: "While the form narrative indicates that all roof surfaces of the project will be painted with the Coolshield SOLACOAT Waterbased Gloss Coating, the provided testing report for the Coolshield SOLACOAT Waterbased Gloss Coating does not take into account the different materials that the product will be applied to. Therefore, the test does not accurately reflect the SRI values for the project. Provide additional testing reports for each material that the paint product will be applied to" Can anyone cast an opinion or contribute an experience on this subject. Thanks.

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Fri, 12/09/2016 - 18:31

The assumption you made: the paint is compliant, therefore whatever you paint will be compliant, is not unreasonable, or that uncommon. However, the texture of the surface has a lot of impact on the SRI value. For example a irregular surface can actually cast shadows on itself and reduce the overall SRI value.You'll need to contact the paint manufacturer and find out which material(s) they tested the paint on and hope that those match the materials you painted. If not, you may need to have additional testing performed, if practical.

Sat, 12/10/2016 - 06:38

Thank you for your input Charles. You are right, we are painting various types of roof areas while as the test was done on a metal roofing. I did contact the manufacturer for additional testing. The problem is that when various types of roofing are involved, chances are that there will not be matching tests. Moreover, a zone of the roof is covered with white gravel. In that case, according to your comment it will lessen the SRI of the paint. I am sure that you are right although it sounds a bit weird that casting shadows will have a negative impact. Anyways, thanks again.

Sat, 12/10/2016 - 08:47

I've inquired about "white " gravel in the past and essentially the Reviewers will see it as a black surface (SRI 0) due to the shadowing effects. Again, logically the SRI is higher than that but it simply cannot be given a standard value since how it behaves is very specific to your project's location and where you place the gravel on the roof relative to other features. You would need to perform testing of the installed gravel surface, in order to claim any SRI value above 0.

Wed, 05/17/2017 - 06:25

My project is looking at getting white gravel tested to determine the SRI. There is a layer of drainage cell and a protective plastic sheet underneath. Is any one familiar with testing grvael? Is there a specific methodology the lab needs to undertake to determine the SRI? Note white gravel is listed with a SRI value of 79 on page 122 of the LEED New Consturction Reference Manual V 2009 in Table 1.

Thu, 05/18/2017 - 14:36

John: Note that SRI for Typical Roofing Materials listed in Table 1 (page 122) provides examples however the text states "these values are for reference only, not for use as substitutes for actual manufacturer's data." Check out the Cool Roof Rating Council website for testing methodology. http://coolroofs.org/product-rating/product-testing

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