Avoid Air Invasions
December 21st, 2011 by Magen Howard

Properly insulated homes improve your comfort and lower energy bills

Dark smudges or staining on your insulation means you have air infiltration, and your insulation is doing little more than catching dust. Create an air barrier for more comfort and lower energy bills. Photo courtesy of Blue Grass Energy

Dark smudges or staining on your insulation means you have air infiltration, and your insulation is doing little more than catching dust. Create an air barrier for more comfort and lower energy bills. Photo courtesy of Blue Grass Energy

We all know the symptoms of a house that is leaking air. Drafty halls in winter lead to rooms that suffocate in summer. Then there is the most uncomfortable pain of all: high electric bills.

Talk to an energy-efficiency expert from your local electric utility, and one of the first things he or she will do is ask about insulation in your house.

What type do you have? Is it in the attic, walls and floors? How about the basement or crawl space?

Chances are leaky homes are not properly insulated. But it takes more than a roll of the familiar pink fiberglass to stop air invasions.

A “thermal building envelope” separates you from outside elements. It is like wearing a coat when it is cold. If you zip up your coat, it is nice and warm, but if it hangs open, you are left freezing.

The way to avoid the chill is to properly seal the building envelope and create air barriers, then install insulation. This will keep hot air out in summer and cold air out in winter.

Sealing your home’s thermal envelope involves applying caulk and foam to cracks and gaps, and correctly installing insulation. If the insulation is not installed properly, it will not be as efficient. Typically, incorrectly placed insulation leaves gaps between walls and doors or windows, or where the ceiling meets the walls.

If there is a gap in insulation, heat gets through, warns Peter Criscione, a manager with E Source. The company works with the Cooperative Research Network, a division of the National Rural Electric Cooperative Association that monitors, evaluates and applies technologies to help electric cooperatives control costs, increase productivity and enhance service to their members.

“It comes down to finding quality installers,” Criscione says.

Understanding air infiltration is only half the battle. You have to find and stop the invaders.

Because heated air rises and will work its way out of the living space, capping the home is important to prevent heat loss.

If your electric utility offers home-energy audits, take advantage of them. Your co-op’s energy adviser will determine if your home needs a blower-door test—one of the best ways to find out how much air goes in and out of your residence every hour.

If a thermal imaging camera is available, the auditor can pinpoint exactly where your home loses air. Typical culprits include the roof, around doors and windows, recessed can lights, attic hatches and pull-down stairs, and unfinished basements or crawl spaces.

Don’t overlook the obvious. Check where ceilings and floors meet the walls, too. Do you routinely have to clean a cobwebby corner? That’s a good indication of air infiltration because insects like fresh air.

Caulk, weather stripping and expanding spray foam should take care of problem areas listed above. You also can make a box of rigid foam board for the attic pull-down stairs.

But insulation does no good if you don’t have proper air barriers—if your house jacket isn’t zipped. While loose-fill fiberglass or fiberglass batts keep heat from moving in or out of your house, they do little to stop air flow.

In fact, if every single joint and crack is not sealed with caulk or expanding foam, your fiberglass batt insulation does little more than catch dust.

Insulation that is discolored or has blackening around the edges indicates there is air infiltration—dust being blown through the fiberglass and getting trapped.

Cellulose, made from recycled newspapers and blown in, provides good attic insulation because it does more to stop air flow. Foam insulation, while the most expensive, also boasts the highest R-value—the effectiveness rating given to insulation—and completely blocks air.

The information box above will help you determine what type of insulation is right for your home. Your utility’s energy professionals can help.

Check the website EnergySavers.gov for more information about insulation. It has tools for making smart decisions about insulation and other topics related to energy efficiency.

Magen Howard writes on consumer and cooperative affairs for the National Rural Electric Cooperative Association.

Choose the Right Insulation for Your Home

  • Your home generally has one of three types of insulation: material fibers such as fiberglass or rock wool, cellulose or foam. Each has a different R-value—the rating system for insulation’s effectiveness. The higher the R-value, the better the insulation will prevent heat transfer between indoors and out.
  • Foam has the highest R-value and creates an air barrier, but it is also the most expensive. Cellulose is behind foam in R-value, followed by fiberglass and rock wool. If you create an air barrier with fiberglass or cellulose, that increases the R-value.
  • How much insulation and what kind you choose largely depends on where you live and whether you have a newly built home or an existing home you want to retrofit. The right insulation also depends on your payback period.

Here’s a general primer on insulation:

  • Batts or rolls: These are the fiberglass or rock wool types. They are generally made to fit between wall studs.
  • Loose fill: Fiberglass, rock wool or cellulose can be blown in, which makes it ideal for attics and other cavities, like walls. Fiberglass and rock wool require an air barrier before insulation installation, which means the cavity needs to be filled with caulk and foam. Cellulose does a better job of blocking air flow by itself.
  • Rigid foam board: This works for placement against exterior walls and shared walls with attics, and must be sealed into place with caulk or foam. It is typically more expensive, but good for colder climates.
  • Foam in place: This foam insulation is sprayed in and is ideal for cracks and gaps, such as spaces around windows and doors. Use low-expansion foam in these narrow spaces.

See the insulation zip code calculator on http://www.EnergySavers.gov to find out how much insulation is right for your area.
Source: http://www.EnergySavers.gov