Is Grunge Cool? Roofing's Under-fulfilled promise
Robert Holden, HESS
A lot has been made about the energy efficiency of roofing systems, membranes and coatings. None bigger, than the potential reduced cooling costs of reflective or "white" coatings used in roofing. This is a trend originating more in warmer climes, but as we all begin to struggle with finite energy resources, has begun to make in-roads in Canada.
I truly believe that the proponents of this concept mean what they say and have demonstrable evidence to support this technology. After all, we all know that snow reflects a high percentage of solar energy and it's white. Snow is also an excellent natural insulator and encouraging a safe build-up could contribute to reduced heating costs in the colder seasons. The difficulty is, that for a surface to be reflective it should be free of impurities, imperfections and most importantly it must be clean.
This is the point when reflective membranes begin to diverge from the promised performance characteristics. There are many reasons property managers clean roofing systems; repair, inspection and aesthetics. However, the idea of cleaning a roof as part of a regularly scheduled preventative maintenance plan is largely unheard of. What has been promoted to government, architects, engineers and code writers is that "white" roofs will save energy. The concept of cleaning roof surfaces to maintain reflectivity is rarely touched upon.
The general notion in the minds of property managers, architects, designers and professional roofers is that once a roof is constructed or installed it will perform as expected with little or no maintenance required. We all tend to forget about maintenance on our automobiles and other equipment, when did you last check your oil? Roofs are even further removed from our regular agenda. At ROOFTech, a brief straw poll noted that no membrane or coating manufacturer could provide procedures and methods for this type of maintenance.
The issue of cleaning, should not be limited to energy saving roofs, but to all roofs and roofing systems. Deterioration by UV radiation, algae and other contaminants affects all types of roofs and the ability to resist weathering and moisture. It becomes more critical when the system in question is selected because of a Value Added feature such as thermal efficiency. Interestingly, roofs sometimes are cleaned when manufacturers and researchers attempt to investigate these claims. Some governmental bodies allow cleaning of test samples to take place before evaluation of the specimen. It should be obvious that testing aged membranes or coatings AFTER cleaning is wholly incredible and possibly unethical if used to promote products and technologies without adequate clarification of the realities of how this data was collected.
Although it seems obvious to the casual observer, there are some hidden obstacles to initiating cleaning of low slope surfaces as a routine maintenance practice. The evidence is clear that regular cleaning will maintain the reflective qualities of the surface; however, because manufacturers and others have not fully considered the warranty implications, caution must be exercised.
According to Tom Hutchinson of the Hutchinson Design Group, when he investigated this issue with a number of manufacturers, the predominate response was; "Good question, I'll look into that...". Questions about damage, erosion or chemical reaction resulting from cleaning and the implication on life-span and warranty largely drew a blank response. When he asked these same manufacturers about training and certification for cleaning procedures the answers were unanimously negative. Again, promotion of a technology and its' benefits without adequate consideration of maintenance and warranty issues is questionable and a potentially expensive position for any reputable manufacturer to take.
Unfortunately, this reality leaves many owners of these systems in an awkward situation. Do they forfeit the thermal efficiency promised or forfeit warranty and life expectancy? Without guidelines and procedures in place from government or manufacturers a dilemma will continue to grow and fester. The result that will occur without constructive action by the roofing industry, is the eventual rejection of the "Cool Roof Concept" and a further distrust of any "Green" or developing technologies. This in sharp contrast to the emerging construction and performance codes could result in stagnation and litigation throughout the building, maintenance and manufacturing sectors. When this occurs, we all will suffer the penalty.
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