Dear Editor;We read with interest your recent article “Considering a new or replacement roof?” in the May 2002 issue of Buildings magazine.I feel compelled to address several points that the author made. For example, the author suggests that models should be based on a variety of factors such as heating- and cooling-degree days, energy costs, etc. He is absolutely correct, and that’s why the calculators that we use at Stevens Roofing Systems have, and always have, taken these factors into consideration. His suggestion that a suitable calculator has not yet been developed is simply not true, and your readers should know better.Second, the author suggests roof color changes after installation and exposure to the elements is again correct. The implication of this is that white roofs get dirty and are therefore less reflective. That’s precisely why that in order to meet the EPA EnergyStar® requirements, the roof has to undergo two tests to determine solar reflectivity: one to determine the initial solar reflectance, and another reflectivity test three years later, when the roof is good and dirty. For low slope, commercial roofing, the membrane must have an initial solar reflectance of 65 percent or greater, and a solar reflectance of 50 percent three years after installation. For white Stevens EP brand of TPO, the initial reflectance level was 86 percent and after three years it was 71 percent. Furthermore, it can be washed and restored to 99 percent of its original reflectance. …Third, the author suggests that manufacturers of white membranes design these products to “chalk or release fillers onto the roof surface.” While some manufacturers might do this, most white roofing membranes sold today do not chalk. Fourth, the suggestion that insulation is a good way to control energy loss and reach a specific energy efficiency level is a good one. Building owners should be able to reach their desired energy savings level through a combination of factors including roof color and/or insulation. It just so happens that the roof’s color can offset the amount of insulation needed and help the owner significantly reduce his/her energy costs at the same time. And it’s much less costly to purchase a white reflective roof with less insulation, than to purchase a black roof and add extra insulation. The Stevens Life Cycle Cost analysis, in fact, tells building owners exactly how much added insulation he/she will need to get to the same savings level with a black sheet. Many gray roofing materials, while perhaps slightly better than black in terms of reflectivity, still don’t meet the minimum reflectivity requirements of the EPA EnergyStar program. …Lastly, the author makes the assertion that “using reflective roofs in the northern United States may actually increase energy costs by decreasing solar heat gain in winter months.” This scenario might be true for companies in far northern areas that HEAT and cool with electricity. Most companies don’t do this, however. Instead, they heat with gas and cool with electricity. Since gas is a significantly cheaper fuel, there is no real benefit to the “solar gain” and, in any case, many of those roofs would be under snow. In reality, we have looked at many calculations over the past 15 years or so and are hard pressed to find any geography in the United States where the building owner does not benefit from having a white reflective roof. …Excerpts from a letter from Thomas E. Gallivan, Marketing Manager, Stevens Roofing Systems, Holyoke, MAI read the article entitled “Considering a new roof or replacement roof?” with much interest. There are a few inaccuracies that we believe your readers should be aware of.The article represents that manufacturers of white roof membranes are driving the trend to white reflective roofing. The fact is that scientists, NASA, and the U.S. government all agree white reflective roofing saves energy, reduces the effects of urban heat islands, and improves outdoor air quality. State and local government and energy service companies are offering rebates for as much as $0.35/sf for installing white, reflective roofing. The U.S. Department of Energy and the Environmental Protection Agency introduced the EnergyStar Roof Rating program to promote the benefits of reflective roofing. The benefits of white reflective roofs are so clear that many manufacturers of built-up roofing, EPDM, and other dark-colored roofing now offer white thermoplastic roof options to satisfy this demand.The writer states that “Insulation is the best understood method of controlling energy loss.” What he doesn’t point out is that foam insulation will change its “R” value at elevated temperatures. The best way to protect and maximize the “R” value of your insulation is to keep it cool – use a white reflective roof. …We do agree with the writer that the owner or specifier of a roof should evaluate the performance record of a roof system. However, we would also suggest that the owner/specifier not base their roof decisions on installed cost, but rather the complete life-cycle cost of the roof, including installed cost, life expectancy, average maintenance costs, energy cost/saving calculations, and disposal costs.Excerpted from a letter from Brian Whelan, Vice President, Sales & Marketing, Sarnafil Inc., Canton, MA
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