"Heat Island Effect" and asphalt shingles.

In this discussion, I will share the "Reality" of Heat Island Effect created by your asphalt shingle roof system.

MANY people are confused by, or have little knowledge regarding solar radiation, and the energy demand it creates. This is "Low Hanging Fruit" friends, so let's deal with that first.

The number ONE issue I face when discussing this topic is that all white roofs are "Cool Roofs". I speak to Professors, Architects, Engineers, and Government "Officials" who debate the esoteric, and ignore one of the most principle rules of physics: "Solar Radiation". Cool Roofs are almost exclusively measured by their ability to reflect solar radiation.

Please bear with me here, because I really need you to understand the following: Petroleum based roofing products (asphalt shingles, modified bitumen, and built up roofing) ABSORB the sun's energy, and retain it well into the evening.

But Ron, I've got white asphalt shingles on my home, so I've got a "Cool Roof", right? The answer is NO. The sun "sees" all petroleum products as "black", and your shingles may reach temperatures up to 100 degrees (assume all measurements to be Fahrenheit) hotter than ambient temperatore.

Example: If you change from a black asphalt shingle roof to a white asphalt shingle roof, you will not qualify for any energy rebates. The white granules embedded in asphalt shingles have very little reflective value. I don't care if the granules were made of chrome, your roof will be hot.

This energy absorption creates a roof surface temperature approaching 180 degrees, and greatly stresses attic insulation, and is a strong influence on your average energy consumption. For those of you who may be ambitious, try to touch them on a hot day. Now that's kind of like your Mother telling you not to touch the stove, but doing it anyway. Mom gets the Bactine, and you shout "blow it, it burns".

This is where you will say, "I live in a very cold climate", so why should I care? In your area, you may have more heating days than cooling days. So you would benefit from it, but most of the country (and world) do not live in that environment. I'll get into more regional discussions at a later date.

The best measure of a material's ability to reflect radiant energy is it's "Solar Reflectance Index" (SRI). Asphalt shingles rate very low at about .27, but I'll get into the SRI a bit later as I don't want to overload you with data. I will show you where to go, and you will see the published statistics. I do not feature EnergyStar in my assessments, as they allow manufacturers to publish their own statistics, and many times the manufacturer even owns the testing laboratory. How's that for a "Fun Fact"?

More on Heat Island Effect in the next post.

Have a happy, and productive day. Always remember to keep looking "UP".

Respectfully,

Robert R. "Ron" Solomon
CCC1325620 (Florida)