R value


Assessing Insulation Efficiency

An R-value is a measure of resistance to heat flow: the higher the R-value, the greater the effectiveness of the insulation material being evaluated.

The U.S. Department of Energy has established a set of R-values for different sections of the country based on climate and local energy costs. But in any area, factors affecting an insulation material’s resistance to heat flow include:

  • Material type, thickness and density
  • How the material is installed in the building
  • Where the material is installed
  • Type of heating and cooling system available

Insulation that is compressed will not yield a full-rated R-value. In a multi-layered installation, the R-values of individual layers are figured separately, then added together to arrive at the correct computation. Wall or ceiling insulation will provide a somewhat different R-value than the R-value of the insulation material itself. This is because a certain amount of heat flows around the insulation through studs and joists.

Bottom line: Installing more insulation increases the resistance to heat flow, resulting in higher R-values. And simply stated, higher R-values translate to a more comfortable home environment.

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