In the last two metal roof posts, we have looked at the reflective pigments used in some metal roof coatings and also the airspace between the metal and your home’s framing which can be achieved with some metal roofs. Both the reflective pigments and the airspace as a thermal break are very effective at keeping summer heat out of your home’s attic.
However, there is a third way in which metal roofs keep your home cooler in the summer and reduces your air conditioning costs.
That is through its high emissivity. Now, the “emissivity” word sounds more complex than it is. What really happens is that, even though metal will get hot sitting out in the sun, it quickly loses that heat back to the sky as soon as the sun sets or even goes behind a cloud. In fact, even a gentle breeze can quickly carry away any absorbed heat.
On the other hand, roofs made of other materials tend to absorb the heat and hold it a long time. In fact, many roofs will continue to radiate heat into the structure’s attic even many hours after the sun has gone down.
If you have ever been alongside a brick structure on a summer night, you have noticed stored heat radiating from the bricks. This same thing happens with many roofing materials, except metal.
So, if energy efficiency is one of your criteria when you choose a new roof, consider that metal roofing is likely your best option. It’s a great way to permanently reduce your air conditioning costs and make your home more comfortable.
This is why most metal roofs are Energy Star listed and they also can be eligible for utility rebates and even tax credits in some cases.