There are many reasons building owners clean their roof
systems—aesthetic preference, functional use, and to assist
in roof system inspection and maintenance. But the idea of cleaning
a roof system to allow a roof membrane to perform one of its
intended functions—reflecting the sun's rays—generally
has been ignored in the roofing industry.
Although the "cool" roofing movement was unknown a few years
ago, it is gaining momentum because of the concept that roof
surfaces can provide energy savings. There are numerous points of
discussion regarding this concept, but one that remains seemingly
unaddressed by many manufacturers, code bodies, associations and
the research community is that roof systems get dirty. What has
been circulated to government agencies, code bodies, and the design
and roofing communities is the hypothesis that white roofs will
save energy, but the issue of cleaning roof surfaces to maintain
reflectivity rarely is brought into discussion. In fact, some
manufacturers have gone to the extent of declaring they never
promised a roof would stay white.
Following are my thoughts and opinions regarding the means,
methods, effects, consequences and realities of cleaning soiled
roof surfaces to maintain roof reflectivity.
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