Question: How much cooler can I expect my attic to be after I’ve installed the green energy radiant barrier?
There are a lot of variables that can affect the attic air temperature, but usually it comes down to two things: the amount of heat your attic is gaining and the amount of airflow passing through. These two factors alone can create a temperature difference of anywhere from 5°F to 30°F; let’s assume for the sake of an example, that your attic is 130°F. With enough holes in your roof, we could eventually get that temperature to drop to close to ambient (outside air) temperature. By forcing enough air through the attic space, we can drop the air temperature 20°F, 30°F or even 40°F. Proper and adequate ventilation is the key to lowering your attic air temperature.
The problem is that attic ventilation has very little effect on the top surface temperatures of attic insulation; surface temperatures are directly affected by radiant heat.
Heat Gain and Surface Temperatures & Why It Matters
You want to lower the surface temperatures in your attic because these are what directly affect the heat gain inside your home. AtticFoil™ will reflect 97% of the radiant heat coming off your roof, which is normally then absorbed by your insulation and ultimately heats up your home. Just like a quarter sitting on the ground in direct sunlight is burning hot from absorbing radiant heat – so is your attic insulation. However, if you found a quarter in the shade, even on a hot sunny day, the surface temperature of that quarter wouldn’t be very different from the ambient (air) temperature outside. The same is true for your attic insulation; radiant barrier acts like shade to keep the top of your insulation cooler. These two additions (proper cycle of ventilation and a radiant barrier) will not only dramatically improve the temperature of your attic, they will improve the overall heat load on your entire home which results in energy savings and a more comfortable living space.
Even with the Radiant Barrier, My Attic is Still Very Hot. What Now?
If you have installed a green energy barrier and you still find that your attic air temperatures are unbearably hot, then you have really bad ventilation. Your first goal is going to be to try to increase your attic ventilation. Ideally, after you install a radiant barrier the air temperature inside the attic should probably be within 10 to 15 degrees of ambient temperature. If it’s MORE than that, it’s kind of like having a clogged drain: the hot air wants to go up and out of the attic but because of the lack of attic ventilation it’s essentially backing up and it’s filling up the attic with hot air. So when you combine good (or decent) attic ventilation with radiant barrier you should have a significantly cooler attic. But, even more importantly (and don’t get too hung up about the air temperature), you’re going drop the surface temperature of the insulation – and that’s really what drives energy savings.