Only about one-fifth of homes built before 1980 are well insulated. Is yours?

To get an idea of what insulation could do for your comfort, your pocketbook, and the climate crisis, consider what it's already doing: without existing residential insulation U.S. carbon dioxide emissions would increase 15%. That's 1.35 trillion pounds of carbon dioxide, and it would take a forest of 300 million acres, equivalent to all of our harvested cropland, to take it back up.

The savings for existing insulation are nearly $84 billion in avoided heating and cooling costs per year! So while insulation requires up front costs, it's also one of the most rewarding, and long-lasting, cost savings and climate benefits. The industry has calculated that if all U.S. homes met just the insulation standards in the Model Energy Code from 1992, total residential carbon dioxide emissions in the U.S. would fall nearly 30%.

Insulation even helps with creature comfort, making it cooler in the summer and warmer in the winter. Combined with a good house sealing effort it can also reduce persistent moisture-related problems such as floor squeaks, drywall cracks, and condensation damage.

The most cost-effective solution really depends on your house -- how much insulation you have already and how it's heated and cooled -- as well as your local climate. Insulation impact is measured according to its R-value. The R-value can range quite a bit; the higher the number, the better insulated your home will be. Different parts of the country and different parts of your home require insulation with different R-values. In general, ceilings (with attic or cathedral pitches) call for R-49 in most of the US, walls should be R-13 to R-18, basement interiors should be R-11 to R-19, and exteriors should be R-10 to R-15. To learn more about what's best for your situation check out this Department of Energy map, fact sheet , and calculator. Your local utility may have even more specialized help available on its web site.

While some insulation, particularly laying down fiberglass batts in an attic, can be done by you, it's worth considering professional help. Insulation materials can be quite messy, and to get the maximum conservation value they must be installed correctly. The North American Insulation Manufacturers Association has tips for both finding and getting the most out of a contractor and for doing it yourself.

Whether you get help from a professional contractor or do it yourself, state and local governments and your utilities provide financial incentives for insulation, so don't miss out on the savings. If a check from the government isn't enough, check out your potential return on investment, and compare it to any forays you might have had on the stock market. If energy prices continue their upward trend, insulation could be your most solid performer.

Reinsulating Your Home

  • How well insulated is your house? Unless you were there when it was installed, there is a good chance that your home wasn't properly insulated when it was built.
  • What are you looking for? Fiberglass insulation usually looks like a sheet of pink, white, or yellow fluff with a backing. There are also various types of blown-in cellulose insulation that might be white, brown, or grey. Insulation comes with an R-value that tells you how effective it is; the higher the R-value the better the insulation. Visit your local home store to see the various types of insulation.
  • Now that you have a sense of what you're seeking, the first place to look is your attic. Just like your body, homes lose the biggest chunk of energy off the top, so a well-insulated attic can save you 20 to 35% in energy bills. If there is bare space between all of the wall framing, you don't have insulation there. If there is insulation but it has been there a long time, ask a professional or get help at your home store to determine whether it should be replaced.
  • Also look at your walls and floors adjacent to unheated spaces such as basements, crawl spaces, and garages. Here the structural elements are usually exposed so, again, look to see if there is insulation in there. If not, it's an opportunity for improvement.
  • Exterior walls are the biggest detective challenge because it's not generally desirable to poke holes in drywall. If you're on top of your D.I.Y. skills, turn off the electricity at the fusebox, carefully remove an outlet face-plate, and look outside the box for signs of insulation. You may want to have a contractor do this for you.