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What Is High R Value Insulation?

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  • Written By: Adam Hill
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  • Last Modified Date: 23 August 2014
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Thermal insulation is an important feature of any home or business. Apart from drastically reducing heating and cooling costs, it provides a comfortable uniformity in temperature throughout a structure. Different types of insulation have different levels of efficiency when it comes to blocking heat transfer. This efficiency is expressed as the R value of the insulation. High R value insulation is that which blocks heat transfer relatively efficiently, compared to other types of insulation.

The R value is a measure of how well an insulation slows down or blocks heat transfer under specific laboratory conditions. World-wide, the mathematical definition of R value is kelvin square meters per watt. By this calculation, the R value of most insulations is between zero and one.

In the United States, R value is measured with degrees Fahrenheit rather than the kelvin scale. This will usually result in a small whole number for an R value. In general, increasing the thickness of an insulating layer will increase its effective R value. However, it must be taken into consideration that insulation can only block heat loss through walls, floors, and ceilings, but not through window glass or other materials.

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Most of the materials typically used to block heat transfer in homes and offices are low R value insulation. This is usually all that is needed, but high R value insulation is also available for certain applications. The insulation with the highest R value is, perhaps ironically, nothing at all. That is to say, a vacuum provides the most ideal insulation. Vacuum insulated panels have an R value of as high as 50, compared to approximately three for conventional fiberglass insulation.

Another high R value insulation is a material known as Aerogel®. It is derived from a gel material and actually consists of more than 99% air in its finished form. It is highly translucent and lightweight, but has impressive insulating properties. Its R value is approximately 10 - not as high as that of vacuum insulated panels, but high enough to make it a type of high R value insulation.

The R value of insulation that each person needs to use in his home or office depends mostly on the local climate, the the type of heating or cooling used in the structure, and other factors. Even low R value insulation can make a significant difference in the efficiency and comfort of a home or workplace. Whatever its R value, insulation should always be installed in such a way to ensure that it performs at its highest potential R value.

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jcraig
Post 4

@kentuckycat - The reason a vacuum would work the best is that, by definition, a vacuum doesn't have any molecules in it. If there are no molecules, there is nothing to transfer the heat to the outside. Of course, it is impossible to make a perfect vacuum, especially with windows. What a lot of companies do now is put argon gas into one of the gaps. The gas makes it harder for the heat to escape compared to regular atmospheric air.

When we had our new home built several years ago, we opted for the blown in insulation that is made from old denim. It has worked great so far. The blown insulation R value is very high and doesn't wear down as quickly as regular fiberglass insulation may. Besides that, it is a biodegradable type of insulation that is recycling something that would have otherwise ended up in a landfill. We are very happy with the choice and would definitely recommend it.

kentuckycat
Post 3

@titans62 - If that is how heat goes from the inside to the outside, why would a vacuum work the best like the article says?

What are the normal R values of insulation that you buy at the store? I have been thinking for a few years that I really need to get under my house and replace that insulation. I was under there not too long ago and noticed that the insulation is starting to fall down in a few places and is dirty. I'm pretty sure dirt also compromises the effectiveness of insulation.

I live in a pretty cold climate, so having good insulation under the house really cuts down on the heating bills. We have hardwood floors, too, so if it gets cold under the house, you can feel it more than if you had carpet. I have never heard of the Aerogel product. Does anyone have any experience with this and now if it can be used under a house?

titans62
Post 2

@stl156 - Good questions. First off, any insulation should protect against heat transfer in both directions. To understand it, just think about how heat is transferred at the molecular level. Something just gets hot because the atoms are moving very quickly. Warm air is warm because the atoms are crashing against each other. When you have insulation, it creates little pockets that force the molecules to move slower toward the outside. Thicker insulation works better because there are more pockets that the molecules can get trapped in.

Keeping that in mind, you should choose the right insulation for your price range and DIY ability (assuming you plan to do this on your own). Whether you have fiberglass insulation or rigid panels, it will be the insulation R values that determine the effectiveness. In my experience, using the panels is easiest for vertical walls. Good luck on your project.

stl156
Post 1

Wow, I didn't realize there was so much you had to take into consideration before buying insulation. We just moved into a new house, and it had an unfinished garage with just bare wood walls. Since we plan on using the garage for more than just storage, we are looking to insulate it and add drywall. What I am trying to decide at the moment is what type of insulation I will need for it.

If I understand correctly, insulation should not only keep heat in, but should also keep air conditioned air in the garage in the summer, right? If that isn't the case, what special types of insulation are there that work for both heat and AC?

I would also appreciate anyone's suggestions about the best type of insulation to use. I know the fiberglass rolls are pretty common, but how do they compare to the rigid sheets and even the blown insulation?

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