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Is your home’s envelope well sealed?

When you see the word “envelope,” what comes to mind? Usually, we think of the outer covering that our mail comes in. However, you could save money on your energy bill if you focus on your home’s envelope, which consists of its outer walls, windows, doors and other openings.

A well-sealed envelope, coupled with the right amount of insulation, can reduce your energy use and your utility bills. According to, nine out of 10 homes in the U.S. are under-insulated. Homeowners can save an average of 15 percent on heating and cooling costs by air sealing their homes and adding insulation in attics, floors, crawl spaces and basements.

To determine if your home’s envelope is in good shape, Clay Electric Cooperative and Safe Electricity recommend having a home audit conducted to pinpoint the leaks that allow energy to escape your home. A qualified energy auditor will include an insulation check as part of a whole-house energy assessment and will identify areas of your home that need air sealing or insulation repairs.

DIY home energy audit

If you would like to complete your own DIY audit, find out the following:

  • The type of insulation in your home.
  • The R-value (rate of thermal resistance) of your insulation. Typically, the higher the R-value, the more effective the insulating. Depending on where you live, you do not necessarily need the highest value; it depends on your local climate.
  • The thickness or depth of the insulation you have.
  • In a newer home, the builder can identify the type of insulation used and where it is located. In an older home, you will need to perform the inspection yourself. To complete a DIY energy assessment, you will need to check the following items:


In the attic

  • A rule of thumb when inspecting the attic insulation is if the insulation is level with or below the attic floor joists, you need to add more insulation.
  • If you cannot see any of the floor joists because the insulation is well above them, you probably have enough, and adding more may not be cost-effective.
  • Insulation should be evenly distributed with no low spots. Check throughout the attic to determine if there are any thin spots.
  • Make sure the insulation in your attic has the appropriate R-value for where you live. Check the value printed on your existing insulation. If you cannot find the value, measure the depth of the insulation in inches. Multiply the depth by the following insulation type: 3.2 for fiberglass batting, for the loose fibers category, multiply by 2.5 for loose fiberglass, 2.8 for rock wool and 3.7 for cellulose. Then check’s recommended R-values. If the calculated value is less than the recommended levels for your region, then you should add more insulation.


Behind the walls

  • Turn off the power to the outlet before beginning this check. Then use a voltmeter or voltage tester to confirm there is no power before beginning work.
  • Remove the outlet cover and shine a flashlight into the crack around the outlet box. You should be able to see if there is insulation in the wall and possibly how thick it is.
  • Pull out a small amount of insulation if needed to help determine the type of insulation.
  • Check outlets on all floors. Just because you find insulation in one wall does not mean it is uniform throughout your home.

To learn more about energy efficiency and electrical safety, visit