9/28/2017 D+D In Depth - 2017: A Look at the Past and Future of <br>Cool-Roof Coatings http://www.durabilityanddesign.com/archive/index.cfm?fuseaction=view&articleID=6132 1/6 MY ACCOUNT | LOG OUT | SUBSCRIBE | ADVERTISE Color + Design Building Envelope Decorative Finishes Maintenance + Renovation Coatings Technology Good Technical Practice D+D NEWS MAGAZINES RESOURCES VIDEO + WEBINARS COMMUNITY CLASSIFIEDS ABOUT Advertisement | September 2017 Next > 2017: A Look at the Past and Future of Cool-Roof Coatings BY KURT SCHWAHN, ANVIL PAINTS & COATINGS INC. In a year that’s turning out to be one of the hottest on record, cool-roof coatings are proving to be, well, pretty cool. The debate rages on as to which type of roofing material is the most durable. How long does the average roof last? Contrary to popular thought, a roof’s longevity is not determined by the substrate. Whether a roof is composed of metal, slate, tile, rubber membrane or conventional asphalt, fiberglass or wood shingles, the answer is the same: A roof lasts until it starts to leak.
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9/28/2017 D+D In Depth - 2017: A Look at the Past and Future of <br>Cool-Roof Coatings
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2017: A Look at the Past and Future of Cool-Roof Coatings
BY KURT SCHWAHN, ANVIL PAINTS & COATINGS INC.
In a year that’s turning out to be one of the hottest on record, cool-roofcoatings are proving to be, well, pretty cool. The debate rages on as to whichtype of roofing material is the most durable. How long does the average rooflast? Contrary to popular thought, a roof’s longevity is not determined by thesubstrate. Whether a roof is composed of metal, slate, tile, rubber membraneor conventional asphalt, fiberglass or wood shingles, the answer is the same: Aroof lasts until it starts to leak.
The first generation of cool-roof coatings were bright white, which reportedly reflects up to 90 percent of the sun’s rays and lowers heatflux by 60 percent. PHOTOS COURTESY OF ANVIL PAINTS & COATINGS INC.
It wasn’t long ago that the only option for sealing a leaky roof was tar. Tar is the brown, oilyresidue left over from coal production. Mixed with petroleum and heated to hazardously hightemperatures, patching a roof with tar was neither the safest nor most environmentally friendlychoice — or, it turns out, the most economical.
When you consider the long-term costs, tar’s initial lower price loses its appeal. Tar roofs areprone to mildew and cracking. And because tar is black, it absorbs the highest possiblepercentage of the sun’s rays, maximizing residual heat transfer into the subject building.
As they say, necessity is the mother of invention. The high maintenance and repair costsassociated with tar, coupled with steady increases in energy costs, spurred the search for asuperior replacement.
FROM TAR POTS TO LAB COATSWhile pouring tar and hoping for the best is still an option today, it’s certainly not the onlyoption. In the past 20 years, the search for cooler, safer, longer-lasting roof coatings has gonefrom the drawing board to the scientific testing laboratory to the stocked-and-ready shelves ofhome improvement and building supply stores across the nation.
The most obvious change has been in the actual color of the roof coatings themselves. Thedifference is, pardon the pun, black and white. The first generation of cool-roof coatingsfollowed the basic principle “the whiter the better.” The reason? Simple thermodynamics.Brilliant white reflects up to 90 percent of the sun’s rays (ASTM C1549-02 Standard TestMethod for Determination of Solar Reflectance Near Ambient Temperature Using a PortableSolar Reflectometer) and lowers heat flux by 60 percent (ASTM C518-98 Standard TestMethod for Steady-State Thermal Transmission Properties by Means of the Heat Flow MeterApparatus).
(As a side note, the simple observation that kicked off the cool-roofing trend has proven to bemore than just theoretical. In fact, switching to a bright-white roof coating can result insignificantly lower heat buildup and therefore reduced air-conditioning costs. In many cases,customers have reported saving up to 25 percent on overall energy bills. Very cool, indeed.)
THE SILICONE SOLUTION
9/28/2017 D+D In Depth - 2017: A Look at the Past and Future of <br>Cool-Roof Coatings
The search began (and continues today) for the perfect combination of resins, acrylics andpolymers to create a durable, easy-to-apply and gleamingly white roof coating. While mostcompanies have their own unique proprietary base blends, many early cool-roofing innovationshave become standard practice across the product spectrum.
Among the early cool-roof innovations that are standard practice among many products today is theincorporation of silicone in the formulation, which helps make the coatings whiter, self-cleaning, awaterproofer and durable.
For instance, most cool-roof coatings today incorporate silicone. The addition of silicone to thefirst generation of grey, solvent-based coatings offered four distinct advantages. First, siliconehelped make the coatings whiter. Second, a special “siliconized” process was able to deliverself-cleaning technology to prevent mold, grease and other contaminants from attaching to anddulling the whiteness of the coatings. Third, silicone is, in itself, a powerful waterproofingagent. Applied in heavy millage and with two properly dried coats, silicone alone can be usedto waterproof a roof. It can even handle ponding water on flat roofs. The fourth advantage ofsilicone is longevity. Coatings containing silicone can deliver lasting durability spanning 25 to50 years. Pretty impressive.
Another earlier breakthrough that is now a common feature of the top coating brands was theintroduction of incorporated fungicides to reduce mildew and assist in keeping the coatingswhite. An interesting innovation from the 1990s was the addition of interlocking fibers. By
9/28/2017 D+D In Depth - 2017: A Look at the Past and Future of <br>Cool-Roof Coatings
spanning gaps like tiny mesh membranes, these fibers helped to solve the problem of liquidapplication over seams and small separations. The introduction of fibers also increased thecoatings’ ability to withstand weathering. Until recently, adding fibers to white elastomericacrylic had proved problematic. Recently, however, one innovative company has figured out away to introduce these helpful fibers to this popular cool-roof coating.
MICRO-CELLS & NANOTECHNOLOGYToday, cool roof coatings are harnessing nanotechnology and the laws of physics to provideever-increasing durability and performance. One such innovation is the ceramic micro-cell.
A micro-cell is a hollow, nano-sized sphere that has undergone a process to remove all thegasses from inside its ceramic shell. As a result, it has become a microscopic vacuum. Thereasoning behind micro-cells takes us back again to simple thermodynamics. It turns out heatconduction through a vacuum runs counter to the laws of physics. In other words, it’simpossible for a vacuum to conduct heat.
When ceramic micro-cells are added to cool-roof coatings, they form a tightly packed, hardlayer as the sealant dries. The resulting dried coating reflects and dissipates heat by minimizingthe path for the transfer of heat, or heat flux. Recent testing of one such product demonstratedan impressive 60 percent reduction in heat flux. Just as white coatings reflect the sun’s rays toreduce heat buildup, micro-cells enable the underside of a structure’s roof to stay cooler longer— resulting in additional savings in energy costs.
WHITE GOES GREENA current challenge for contractors, roofers and all professionals involved in the building andconstruction trades is compliance with governmental and environmental regulations. None hashad more impact than the LEED initiative. Leadership in Energy and Environmental Design(LEED) is a rating system devised by the U.S. Green Building Council (USGBC) to evaluatethe environmental performance of a building and encourage market transformation towardsustainable design.
Cool roofing, with its innate energy savings of up to 25 percent, is helping to lead the charge inLEED compliance. The advent of new resins and polymers with lower volatile organiccompound (VOC) ratings is adding to the case for cool roof coatings as a more environmentallyfriendly choice. As more and more states implement VOC limits of 100 and even 50 VOCs,cool coatings are offering viable alternatives to meet ever-stricter and mandatory environmentalregulations.
9/28/2017 D+D In Depth - 2017: A Look at the Past and Future of <br>Cool-Roof Coatings
The energy savings offered by cool-roof coatings, along with chemistry that is lower in volatile orange compounds (VOCs), play a role inLEED-compliant roofing material selection.
TODAY’S TRENDS, TOMORROW’S INNOVATIONSAs the future for cool roofing expands, so does the need to satisfy customers’ demand forchoices that are aesthetically pleasing and architecturally appropriate. One of the mostinteresting trends is the desire expressed for more variety in color selection. Fast-foodrestaurants and chain stores seek the advantages cool roof coatings deliver, but they also wantto match their signature logo colors. Cool-roofing solutions must step up to the plate anddeliver.
Other customer-driven trends include the need to provide durable, long-lasting, water-basedcoating options. Contractors themselves have expressed the need for easier application, betterflowability of coatings and better roller and pump-based applicators. For them, application timeis money. Anything that can speed the process is saving not only time but money as well.
But perhaps the biggest challenge ahead is to find an alternative to the tried-and-true silicone.While its advantages have already been discussed, its disadvantages are many. For one, it’sexpensive. Perhaps even more challenging is its shelf life. Unopened, cool-roofing productscontaining silicone remain viable only for around two years — and once the seal is broken on acontainer, the product must be used immediately.
Examining new materials and techniques to address the issues of durability, longevity andaesthetics is the work we’re facing now. A recent discovery resulting from the blending of twotypes of resins is showing great promise in solving the age-old problem of cool roof coatings’ability to expand and contract with changing climatic conditions. With the right “secret sauce,”this blend could virtually eliminate the need for caulking and patching. Quick installation, non-intrusive application and reduced roof maintenance could make this product a real gamechanger.
So, what else is on the horizon? As I see it, the cool-roof coating of the future is a single-component elastomeric that can be used on all substrates. It will be easy to apply and offer thesame durability and reliability as the better-quality products already on the market. In otherwords, it will be a better product overall at a very competitive price. All I can say for now is,“Watch this space. The future is not so far away.”
ABOUT THE AUTHOR
9/28/2017 D+D In Depth - 2017: A Look at the Past and Future of <br>Cool-Roof Coatings
Kurt Schwahn, president of Anvil Paints & Coatings Inc., joined the company in 2014 tomanage all operations for future U.S. expansion and to accommodate the company’srapidly growing customer base. Prior to joining Anvil, Schwahn acquired more than 20years of expertise in senior management and major consumer goods manufacturing.Schwahn is a member of the RCMA Roof Coating Committee and the AmericanCoatings Association.
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Tagged categories: Anvil Paints; Coating chemistry; Coating Materials; Coating performance; Cool roof coatings;LEED; Nanotechnology; Reflective roof coatings; Silicone; Solar reflectance; United States Green Building Council(USGBC); VOC content
Comment from Terry Ping, (9/27/2017, 11:03 AM)
Great article...
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