Radiant Barrier Insulation: Some History and Useful Information
This entry was posted on June 20, 2011.
Decades ago, NASA scientists were looking for compact and lightweight materials for heat/cold control in space. They experimented with gold, silver, and aluminum surfaces and discovered radiant barriers. After understanding their importance for heat control they further developed radiant barrier technology that reflected almost all radiant heat away rather than absorbing it. Examples of their use are in spacesuits that can hold heat in while insulating against the extreme radiation of the sun. Another example is the gold foil on the outside of the Lunar Lander.
The material is effective against radiant heat because its natural design reflects this heat away. Radiant barrier technology is in our homes today because the material also has no capacity limits. It will reflect heat away all the time without any performance change.
Thermal insulation on the other hand and any insulation that utilizes R-Values do have capacity limits. Their limits are their R-Value. They can reach a point where they are full and cannot contain any more heat.
Examine a sponge under running water. Eventually, the sponge becomes full and cannot hold any more water. The more R-Value means the larger the sponge. But, eventually it can become filled. That's why more thermal insulation such as fiberglass is always better than less. It allows more heat to be trapped. Once this insulation is full however or has no capacity left, heat starts passing through and the material also holds onto this heat. An example of this is when your home is warmer inside even after outdoor temperatures have dropped. This heat is stored in your walls and roof.
This is not to say that radiant barriers are better insulators than thermal insulation. They are different and both effective. Hopefully this post explains the history of radiant barriers and helps you better understand the different insulation types at work in your home.