You use a lot of energy – and money! – keeping your house at a comfortable temperature. But if there are holes in the “envelope” or “shell” of your home, air from the outside can get into your home and drive up your energy costs.

Sealing the envelope of your home is one of the most cost-effective ways to improve energy efficiency and comfort. Energy Star estimates that appropriate sealing can save up to 20% on heating and cooling costs.

There are three ways to seal the envelope of your home:

• Sealing air leaks to stop drafts
• Adding insulation
• Installing Energy Star windows when replacing windows

Sealing leaks. It may be easy to find some of the leaks in your home, because you can feel and sometimes even see them (for example, around windows and doors). You can seal these leaks with caulk, foam, and weather stripping.

Other leaks may be hidden in attics, basements, and crawl spaces. Common leak spots include:

• Recessed lights
• Outdoor faucets
• Dryer vents
• Attic hatches
• Around light switches and cable, phone, or power outlets
• Chimneys and furnace flues
• The tops of walls that lead up to attic space

To find and seal these hidden leaks, it may be advisable to hire a contractor who can use special diagnostic tools. The expense is often quickly paid back in increased comfort and reduced utility bills.

Adding insulation. There are several common types of insulation — fiberglass (in both batt and blown forms), cellulose, rigid foam board, and spray foam. Different types are appropriate for different places in your home.

The strength of insulation is measured by “R-value” – its ability to resist heat flow. The higher the R-value, the more insulating power. Different R-values are recommended for different parts of your house, depending upon where you live.

Insulating your attic may offer significant savings, and can be a good DIY project if you are handy. To see if your attic can benefit from more insulation, look across your uncovered attic floor. If your insulation is level with or below the attic floor joints, more would probably be helpful.

Remember, however, that even well-insulated attics need appropriate ventilation to prevent mold growth in the summer and ice buildup in the winter.

Installing Energy Star windows and doors. Replacing windows and doors is a big project and may not generate enough energy savings to justify the cost. However, if you are remodeling or building a new home, be sure to choose Energy Star windows and doors. Energy Star windows and doors will not only help seal and insulate your home – they will also act as a sunscreen to protect your pictures, furniture, and carpets.

After Sealing Your Home: Check Air Quality!

After any sealing or insulating project it’s very important to have a professional perform a Combustion Safety Test on your gas and oil burning appliances to ensure that they are still operating safely.

It’s rare that homeowners seal their homes too tightly – especially if it’s an older house. However, if you are concerned, you can hire a contractor to test your home’s ventilation. If your home is too tightly sealed, he or she may recommend that you install a fresh air ventilation system.