Letters

Clarifying CRRC's rating program

In his article, "Sustainability and roofing," March issue, page 26, Tom Hutchinson, principal of Hutchinson Design Group Ltd., Barrington, Ill., presents a comprehensive and educational tutorial about sustainable roofing. However, contrary to the statement in Hutchinson's article, the Cool Roof Rating Council's (CRRC's) rating program does not permit washing for the purposes of establishing three-year "weathered" values. CRRC agrees initial values, though important, should be viewed with caution. By adopting cool roofs as a required element of its Title 24 nonresidential building standards, California exercised such caution, basing its savings calculations on reduced solar reflectance values (of more than 20 percent of initial values) to account for weathering effects.

To qualify as a "cool roof" with respect to California's Title 24, roofing materials must be rated by CRRC and meet 0.70 for initial solar reflectance and 0.75 for thermal emittance. Note these values are for low-slope nonresidential applications, the only application in Title 24 that requires a cool roof. CRRC has initiated its three-year weathering protocol and expects to begin reporting "weathered" values during the second quarter of 2007.

The CRRC Product Rating Program applies to all types of roofing materials, not just coatings. As of March 13, the Directory of Rated Products shows initial values for 148 products, including single-ply thermoplastic membranes, modified bitumen, single-ply PVC membranes, single-ply thermoset membranes, metal and coatings. Not to be overlooked in the discussion of performance over time is the notion that many common building materials and systems experience some decrease in performance over time. For many roofing products, CRRC notes that with proper maintenance, new or near-new performance is achievable.

CRRC wants to remind Professional Roofing readers that CRRC was formed to provide accurate, credible data about reflectivity performance and not to advocate specific performance levels, such as is done by the U.S. Environmental Protection Agency's ENERGY STAR® program and other programs. However, the ENERGY STAR program fulfills the role of advocating to consumers the use of high-performing products, a function CRRC does not provide.

Robyn Beavers
CRRC
Oakland, Calif.

The March issue's article "Sustainability and roofing" by Tom Hutchinson lacks completeness and peer review.

The article contains a statement that reads: "It should be noted that before establishing a three-year value, ASTM tests ... allow a roof covering material to be washed prior to testing. I caution designers and contractors against accepting the same in-field values as those provided by CRRC. The values given are for comparison with other products, not a promise of in-field performance."

This is blatantly wrong. If Hutchinson had viewed CRRC's Web site, specifically information about the Product Rating Program, he would have observed that Section 2.5.2(B) states: "Samples shall remain untouched for a period of three years. After three-year exposure, Test Farm is responsible for coordinating with the Licensed Seller or Licensed OM to send exposed samples to [approved independent testing laboratory] of its choice for testing of Aged Radiative Properties." It does not state in the CRRC program that aged roof products are permitted to be "washed" prior to being tested.

With respect to the cautionary note to designers and contractors regarding the acceptance of in-field values as those provided by CRRC, Hutchinson fails to mention the following substantive facts:

• CRRC does not at this time publish aged roof product radiative property values.
  
  
• ASHRAE Standard 90.1-2001, "Energy Standard for Buildings Except Low-Rise Residential Buildings," specifically has handled this issue by embedding within the provisions a limitation where the benefits of the various reflective roofs used in the simulations "were downgraded to a reflectance of 0.55 to account for the effects of weathering and direct collection."

The net result of Hutchinson's statement is that it has the unintended potential of having a designer or contractor issue a double penalty to a roofing product.

Jonathan Humble, AIA
West Hartford, Conn.

Following is Hutchinson's reply to the letters:

"I appreciate Beavers and Humble bringing to my attention the fact that CRRC's Product Rating Program states the 'samples shall remain untouched for a period of three years.' However, the three years stated is for the test period. The program is silent on the issue of whether samples, after three years of aging, can be washed before testing. This nomenclature is noncommittal and is perhaps why I and the peer reviewers of the article did not see conflict with my recommendation. I would suggest CRRC, if its intent is not to have the samples washed prior to testing and provide the design community with aged, nonwashed membrane reflectance values, specifically state this parameter.

"I understand test farm sampling has just been implemented and, as a result, reporting still is three years away. Unfortunately, the test samples are so small it will be interesting to see whether the values will be of use. With aged reflectance values for only a few products three years away and others even farther away, I still would recommend architects, consultants and contractors proceed cautiously in promising clients cost savings and performance based solely on roof color and remember that when aged roof covering values become available, they are for material comparison only, not a promise of in-field performance.

"With regard to Humble's comment about the American Society of Heating Refrigerating & Air Conditioning Engineers (ASHRAE), the standard mentioned in the article was adopted some time ago. One of the standard's weak points is that it treats all materials equally when it is well-known some membranes, such as PVC, soil much more quickly than do TPOs. The amount of new technical information about 'cool roofing' that has become available during the past few years has been tremendous and made new data and information available so rapidly that programs and hardware quickly become outdated. ASHRAE recognizes this trend and currently is in the process of evaluating whether the thermal reduction credit when using ‘white' roof coverings provided for in ASHRAE 90.1 should be eliminated.

"The issue of cool roofing has touched all segments of the roofing industry and created a great deal of concern and discussion. As with all new concepts and trends, the only real true test is time and experience. Although the time issue is something all roof system designers and building owners will have to wait for, many of us have the experience. Until more conclusive evidence is available with regard to the potential for selecting roof coverings based solely on color, I respectfully suggest those performing roof system design use their empirical experiences to assist in making the correct roof covering selections and recommendations for their clients."