It’s been a couple weeks since we finished applying a fresh coat of roof sealant. Prior coating was a medium gray. New one, as you can see, is a bright white.
We’re speculating we will recoup the cost of the project by the end of the summer due to using less electricity to cool the house. We noticed a difference immediately and can’t wait to see how it affects utility bills.
This is a good example of how LRV, Light Reflectance Value, plays a part in the energy savings equation. In very basic, stripped down terms lighter colors reflect more energy from the sun than darker colors. The original roof sealant was a medium gray with an estimated LRV of 40-45. The new, bright white coating has a LRV of 90.  Here’s a LRV scale for reference:
We’re using Black Jack Ultra from Gardners and they claim it “helps save $ by lowering cooling costs up to 30%”. Whether the actual product does anything to lower cooling costs, I dunno. But I do believe the lighter color is a definite improvement.
Although there is more to the story of heat and energy accume than LRV, this oldie but goodie article of mine explains the LRV part. What You Need to Know About Light Reflectance Values