How A Cool Roof works
Two things about insulating with Roof Coatings that keep a roof cool:
High reflectivity and high emissivity.
Cool roof coating insulation reflects 70% to 90% of the sun’s energy when newly installed. Most of the energy is radiated away. Conventional roofing materials have a reflectivity of 5% to 25%, meaning they absorb 75% to 95% of the sun’s energy. A typical “white” capsheet roof only reflects 25% of the sun’s energy. The absorbed energy is transferred to the building.
Emissivity is the ability to radiate away absorbed heat. This prevents heat from being transferred through your insulation and into your home. Most cool roof coatings emit 90% or more. Even though aluminum coated roofs are highly reflective they are not considered cool roof insulation because they only emit 50% to 60% of the absorbed energy.
In Florida a conventional roof can get up to 180º on hot sunny summer days. Cool roof coating insulation keeps the roof at just 10º-15º above the air temperature. This means a cool roof can be 80º to 90º cooler than a conventional roof.
Cooler roof surfaces means, less heat is transferred into the building and insulation. Therefore if you air condition your building, a reflective roof coating will not only save money on cooling energy but will make the conditioned space more comfortable as well. How much you will save depends on many factors including roof insulation, cooling system equipment and other variables such as roof maintenance savings and extending roof life. In the right situation, reflective roof coating insulation can bring cooling savings of up to 50%, with a reduction in peak cooling demand of 10% to 15%