Selected Answers

From John Ahern of Ahern Painting, Inc on September 12, 2017:
Phil of SpecGuy has made some great points. From m ...read more Phil of SpecGuy has made some great points. From my perspective as an installer of cool roof coatings, we are partial to the cost-benefit of fluid-applied roof membranes (full disclosure). The primary reason why replacing a roof is cost- prohibitive is, it may cost 3-6x more for roof replacement than a PROPERLY applied roof coating with a 15-year warranty. This is a truly monolithic system that is extremely effective when correct roof repairs are made prior to the coating system. The emissivity of the white roof is a secondary benefit. It will lower interior temps 5-10 degrees on average. US Dept of Energy stat: 15% less AC usage on cool roof coatings applied to roof tops. You don't need to be an industry expert to see the temperature benefits of having a white roof top. Check every school bus and notice the white roof tops.

From Philip Kabza of SpecGuy Specifications Consultants on September 11, 2017:
There are several variables to consider including ...read more There are several variables to consider including energy cost savings if any, condition of the existing roof, and the affect of the coating on roof longevity. The higher the existing insulation R value, the lower the direct impact of coating color on through-the-roof heat gain. One issue that is difficult to model is the presence of HVAC equipment on the roof. White coatings will lower the ambient air temperatures, possibly making condensers and air handlers more efficient, especially in high outside air demand occupancies such as hospitals. The existing roof needs adequate remaining life to make the coating worthwhile; this is usually determined by measuring the remaining tensile strength in the roof plies. Higher quality level coatings (urethanes as compared with acrylics) can greatly extend the life of the existing roof, which may be where the greatest life cycle cost savings can take place. I do not know if anyone is equipped with software that will take all of these variables into consideration and give you a dollar figure to sell to CFOs; perhaps another reader can comment on that.