Insulating R-Values Can Vary More Than You Think

Insulating R-Values Can Vary More Than You Think

Insulating R-Values Can Vary More Than You ThinkInsulation is a necessity year-round, keeping heat inside your home during the winter and keeping heat out through the sweltering Georgia summer. Any homeowner who has recently installed insulation should be familiar with R-values (“R” standing for “resistance”), the standards by which insulation is judged. R-values provide a convenient way for consumers to assess which type of insulation provides the most resistance to heat transfer and, thus, which will best serve their needs. Yet, insulating R-values don’t tell the whole story.

To understand why, you need to understand a little about how insulating R-values are determined. In response to fraudulent claims by insulation manufacturers, the Federal Trade Commission established guidelines for the testing of insulation. The basic rules are:

  • Insulation has to be tested with a 50-degree F difference between temperatures on either side of the insulating material.
  • The average of the two temperatures has to equal 75 degrees F.

The R-value is then determined as the temperature difference in degrees times the area of the insulating material in square feet times the time that has passed, all of it divided by the loss of heat in British Thermal Units (BTUs).

Needless to say, you’re unlikely to have a 50-degree house when it’s 100 degrees outside, nor are you likely to heat your home to 100 degrees when it’s 50 degrees outside. So, the test conditions aren’t exactly real-world ones.

The reason this complicates things is that some types of insulation (such as fiberglass batting, or expanded or extruded polystyrene) function better at cooler temperatures, whereas others (such as polyisocyanurate, or polyiso) lose their insulating properties as they get cooler, making them more suited for warm weather insulation. Consulting with a contractor who knows how each type of insulation performs in the real-world conditions of Georgia and the Southeast is essential to finding the type that will meet your needs.

If you have any questions about insulation in your home, want to schedule an assessment, or just want to learn more, visit us at Powers Heating & Air Conditioning. We’re proud to help homeowners in the Peachtree City area.

Our goal is to help educate our customers in Peachtree City, Georgia and surrounding areas about energy and home comfort issues (specific to HVAC systems). 

Image courtesy of Shutterstock

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