| Author |
Message |
Bob Woodburn
Senior Member
Username: bwoodburn
Post Number: 226
Registered: 01-2005
| | Posted on Wednesday, February 06, 2008 - 09:45 am: |    |
Anyone know of an asphalt shingle with an SRI of 0.29, for SSc7.2 (steep)? Thanks. |
(Unregistered Guest)
Unregistered guest
| | Posted on Wednesday, February 06, 2008 - 10:31 am: | |
http://coolroofs.org/ and use their search engine. |
Bob Woodburn, RA, CSI, CCS, LEED AP
Senior Member
Username: bwoodburn
Post Number: 227
Registered: 01-2005
| | Posted on Wednesday, February 06, 2008 - 12:16 pm: | |
Thanks; I did that. The CRRC's "product directory" is a search engine, with a category for shingles or shakes, and you can put in key words. But searching for "SRI" or "asphalt" or "composition" yields no results. And SRIs are not listed, only reflectances and emittances.
It did turn up one certainteed product with a reflectance of 0.29 (which I had searched for), and I have a call in to the listed rep. It also turned up three Armorlite shingles, but they're thermoformed sheet polymer "slate" and "shake" panels, and comparable in cost to metal roofing, perhaps twice the cost of asphalt shingles. |
Don Harris CSI, CCS, CCCA, AIA
Senior Member
Username: don_harris
Post Number: 172
Registered: 03-2003
| | Posted on Wednesday, February 06, 2008 - 01:59 pm: | |
This is copied from the Cool Roof FAQs
6.) How do I compute the Solar Reflectance Index (SRI) of a roofing product?
SRI is an alternative method for considering the radiative properties of roofing materials. SRI is defined by ASTM Standard E1980-01 and is a calculation that uses solar reflectance and thermal emittance. EPA summarizes SRI as “the relative steady-state surface temperature with respect to the standard white (SRI=100) and standard black (SRI=0) under the standard solar and ambient conditions.” SRI is often usedalternative is designed for products that have a low thermal emittance but a very high solar reflectance—the theory is that the higher solar reflectance will outweigh the impact of a low thermal emittance.
The CRRC Product Directory does not include SRI, however, the provided solar reflectance and thermal emittance values can be used to compute SRI. The US Green Building Council uses SRI for some of their LEED rating systems cool roof credits. They have a calculator posted at http://www.usgbc.org/DisplayPage.aspx?CMSPageID=1447. From there, click on the NC2.2 SS link and, when prompted, click "open". Open the "SSc71_2.2a" pdf file.
SSc71_2.2a should actually read SSc72_2.2a. The former is the calculator for non roof items, a typo I guess.
Hope this helps. |
John Hunter
Senior Member
Username: johnhunter
Post Number: 48
Registered: 12-2005
| | Posted on Wednesday, February 06, 2008 - 02:31 pm: | |
Elk also has product that they say meet the requirement with a very limited color selections in their Prestique "Cool Color Series."
http://www.elkcorp.com/products/shingles_prestique_ccs.cfm |
Bob Woodburn, RA, CSI, CCS, LEED AP
Senior Member
Username: bwoodburn
Post Number: 228
Registered: 01-2005
| | Posted on Wednesday, February 06, 2008 - 04:36 pm: | |
Thanks, Don and John. It took some digging and phone calls, but GAF/ELK has confirmed that two of their colors have an SRI of .29, based on a reflectance of .27 and emittance of .92. Now to do the math... |
Bob Woodburn, RA CSI CCS CCCA LEED AP
Senior Member
Username: bwoodburn
Post Number: 229
Registered: 01-2005
| | Posted on Wednesday, February 06, 2008 - 05:01 pm: | |
Two of the three colors in the GAF/Elk "Cool Color Series" qualify. (Cool Weatheredwood doesn't).
Confirmed by the LEED template calculator - SRI of 29 (not 0.29). Thanks! |
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