If you have spent any time browsing the web looking at air conditioning or speaking to HVAC contractors you may have heard the term R-value. If you’ve ever wondered what this term means, this is the article for you. Essentially, the R-value is a measurement of the ability of insulation to resist the heat that is traveling through it.
How is the Measurement Taken?
The measurement is calculated by taking the ratio of the difference in temperature across an insulator and the heat flux running through it. The R-value can vary a great deal depending on the properties of the insulating material used, such as the material, density, and thickness. Some materials are more naturally suited to insulation than others. Many people believe that thicker or denser the material is better for insulation, but this isn’t always the case. The main thing to remember is that the higher the R-value, the better the insulation properties of the material.
The Insulation Location is Important:
Where the insulation is located is also extremely important for the most effective results. If the insulation is installed in a fashion that causes it to be compressed, the R-value and thus the effectiveness could be lowered. Some types of insulation are designed for the purpose of withstanding this kind of pressure, so check your product if you’re planning to insulate narrow cavities. The R-value can also be lowered due to compression by layering a heavier insulation on top of a lighter material. Care should always be taken to avoid leaving gaps and bare areas for maximum thermal resistance. Areas that are not covered can cause a buildup of moisture that will compromise the R-value as the liquid introduces additional weight and compression.
The R-Value of Different Materials:
The R-value of a material is an insulation measurement per each inch of thickness. Every material can have an R-value, but for insulation purposes, some materials are much more practical than others. A common winter material such as snow has an R-value of R-1.0 per inch which makes it an interesting moldable insulating material, but it is impracticable. A more natural “in vogue” insulating material is baled straw which has an R-value of R-1.5. A more common option for loose fill insulation would be cellulose or fiberglass which usually has an R-value in the R-2.0 to R-3.5 range. A common rigid insulation such as plastic foam could have an R-value of R-3.5 to R-8.0 or more. Aerogel is a very popular choice in domestic and industrial applications because it has an R-value of R-10.0. At the top of the list are vacuum insulated panels, which have an amazing R-value of R-30.0 or more per inch of thickness.
Calculating R-Values for Layers of Insulation:
As long as compression is avoided by using the appropriate insulation products, insulation can be layered. It may be the case that you need to know what the combined R-value is for two or even more layers. This is simple, add all of the R-values together to calculate the new R-value. As an example from above: combining a plastic foam R-4.5 with Aerogel R-10.0 would give a total R-value of R-14.5.
For more information, contact Around The Clock Heating and Air Conditioning.