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How Does A Radiant Barrier Work?

 

A radiant barrier is a layer of metallic foil that blocks radiated heat, assisting in the energy performance of a building. First, since Ecofoil Radiant Barrier reflects 96% of radiant heat does not mean it will reduce your bills by 96% each month. As you can see in the example above, radiant barriers work very well at reflecting radiant heat back towards the source, keeping it much cooler on the other side of the product.

 

The Science Behind Radiant Barriers



There are three different types of heat transfer: Conduction, Convection, and Radiation. Let's take a look at how they work.



Conduction - Conduction occurs when there is a direct contact between materials. The classic example of this is setting a pan on a hot stove where the heat conducts into your pan and then into your food, heating it up.



Convection - Convection occurs when there is a movement of air. Imagine a cold room with an portable electric heater in it. As the heater runs the air around it warms and rises into the room. As the warm air rises it causes cold air to drop closer to the floor where it is fed across the heating element and warmed to create another cycle of heated air. This is convective heat - warm air that rises and displaces cooler air until all the air in the space is at equilibrium.



Radiant - Radiant energy transfer is caused by electromagnetic radiation. A practical example is the warmth of the sun on your face when you step outside on a sunny, still day. The sun is not touching you, and there is no breeze pulling the warm air past you, but you immediately feel the warmth of it as your skin absorbs the radiant heat. In fact, the only way heat can be transferred through a vaccum like space from the sun to our earth, is via radiant heat transfer.



Common Examples Of Radiant Barriers
  • Radiant barrier insulations
  • Vehicle Sunshades
  • Survival and marathon blankets
  • The reflective lining on some newer coats and jackets
  • Stainless insulated drinking cups


Traditional insulations are designed to work against coductive and convective heat transfer, but are ineffective against radiant heat transfer. All Ecofoil insulations are radiant barriers that are designed specifically to prevent radiant heat transfer. Using a radiant barrier in conjunction with a traditional insulation is the best combination to prevent multiple forms of heat transfer in and out of a building.





Radiant Barriers require a dead airspace!

In order for a radiant barrier to be effective, it requires a dead airspace on at least 1 side of the product. If you sandwich a radiant barrier between two solid materials, then heat will just conduct through it, rendering it ineffective. The ever popular stainless insulated cups that work so well to keep your drink hot or cold for extended periods, use an airspace or vaccuum between layers to keep radiant heat from penetrating through it. Radiant barriers work on this same principle when they have a dead air space on one side. This allows the radiant barrier to reflect 96% of the radiant heat away from it and only allow 4% through it, making the product a no brainer to use in many applications.



R-Value Of Radiant Barriers

Most radiant barriers themselves have little to no R-Value. This is because they have been engineered to prevent radiant heat transer and work in a completely different way than traditional insulations. R-Value is determined by a materials ability to prevent heat transfer from hot to cold, which includes conduction and convection. There are some companies out there posting big R-Value numbers for their radiant barriers, but those numbers are generally rating the system. This means they are including the product, dead airspace, building materials, etc. If you are trying to satisfy a building code of a specified R-Value, you will need to use a traditional insulation in conjunction with our radiant barrier in order to meet code.

 



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If you would like any other information on EcoFoil Radiant Barriers, please give us a call at (888) 349-3645 or send us an email to customerservice@ecofoil.com. We look forward to hearing from you soon!