Radiant Barrier Department Of Energy Lab Test Results - (Understanding Reflectivity vs Emissivity)

In this video, I'm going to explain the difference between two radiant barrier qualities, which often get confused: reflectivity and emissivity. Basically, reflectivity is the ability to REFLECT radiant heat. Emissivity is the ability to NOTallow heat to be emitted in a radiant form. I'm going to show you a wall example and give you two different examples to show you how this is done. This foil is pressed up against the siding. Assuming this is a siding that is catching sun, it's getting hot, the hot side is the siding, this is the cool side. When the air space (and we're inside the shed, so this is the cool side), when the air space is on the cool side, the foil is working off of EMISSIVITY. So what this does is it inhibits the ability of the siding to release its heat into the shed.Conversely, pretend the foil is not there and you put the foil stapled across the face of the studs here, now you have an air space here. The siding would still get hot, but instead of being restricted, the heat is going to come off the siding, go across that air space, hit this side of the foil and be reflected back. When the air space is on the HOT side of the foil, it's working off the REFLECTIVITY quality. They are similar as far as the ability to impede heat flow, but really if you can, you always want to get an air space to the hot side and work off of reflectivity instead of emissivity. The Department of Energy did a study where they compared the radiant barrier decking (which is TechShield or SolarBoard or some of these other products) that have the foil on the bottom of the roof deck - they work off of EMISSIVITY, which works fine. The Department of Energy's studies resulted that the radiant barrier decking reduced heat flow by about 30%, total BTU reduction was about 30%. Radiant barrier stapled to the bottom of the rafters (AtticFoil-type products) when you're stapling to the bottom of the rafters, reduced heat flow by about 50%. So it was almost doubly as effective at reducing the heat flow into the attic because you're working off the REFLECTIVITY, and because you're covering the bottom of the rafters you are helping reduce some of the thermal bypass from coming in. That's the difference between reflectivity and emissivity and if you want the information (the report from the Department of Energy) from Oak Ridge National Laboratories comparing the radiant barrier decking versus the AtticFoil/sheet foil product, we have it on the website www.AtticFoil.com. If you enjoyed this video, please SUBSCRIBE by clicking the button in yellow, or if you want to see some related videos, click on the videos over to the right. For any other information, visit the websites: www.AtticFoil.com, www.WareHouseFoil.com or www.RoofingFoil.com. Thanks for watching.

Channel: AtticFoil Radiant Barrier Foil Insulation

Views: 75,390

Rating: 4.8989172 out of 5

Keywords: Radiant Barrier, Emissivity, United States Department Of Energy (Government Agency), Reflectivity, Physics (Field Of Study), Oak Ridge National Laboratory (Structure), attic insulation, attic ventilation, ridge vent, TechShield, SolarBoard, OSB, AtticFoil, radiant barrier foil, 97%, foil silver pineapple attic, reflective coating, eshield, prodex, armafoil, installation, green energy barrier, DOE, foil, aluminum

Id: uGP5KobU6R4

Length: 3min 13sec (193 seconds)

Published: Fri Sep 05 2014