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Seal air leaks

Wed, 12/26/2007 - 1:05am — efadmin

"Heat naturally flows from warmer spaces to cooler ones until the temperatures both in and between the two spaces are equal. Inside the home, warm air rises and leaks out the attic and roof while drawing cold air in through the basement. Your home’s shell (walls, windows, doors, foundation, roof, attic, etc.) determines its rate of heat loss, and leaky shells can be responsible for 25-40 percent of the load on your heating system. You can prevent this heat loss by implementing passive heating measures such as improving insulation, sealing air leaks, and replacing or reglazing your windows to minimize heat transfer."

"Air leaks around doors, windows, and electrical outlets; through the fireplace; in basements (between the foundation and the frame); and especially in attics lose as much heat, in the typical home, as leaving an average-size window open all winter long. The extra heating fuel required to compensate for these energy leaks represents up to 800 pounds of CO2 emissions annually."

Making sure your home is properly insulated is one of the easiest and most cost-effective ways to reduce energy waste, save money and reduce your carbon dioxide footprint. "You can increase the comfort of your home while reducing your heating and cooling needs by up to 30% by investing just a few hundred dollars in proper insulation and sealing air leaks."

  • Making sure your home meets recommended levels of insulation for your region should start with checking areas where significant air leakage, and hence unnecessary cost, can occur. These include your attic, ceilings, exterior and basement walls, floors and crawl spaces.

  • Insulation is measured in R-values, a measure of a material’s resistance to heat transfer by conduction (conduction refers to the transfer of heat through a solid object, from its warmer side to its cooler side). The higher the R-value, the better your floors, walls and roof will resist the transfer of heat.

  • The U.S. Department of Energy (DOE) recommends ranges of R-values based on local heating and cooling costs and climate conditions in different areas of the nation. The DOE produces maps and charts detailing these recommendations, found at http://www1.eere.energy.gov/consumer/tips/insulation.html. The DOE also has a zip code insulation calculator for insulation recommendations tailored to your home, found at http://www.ornl.gov/~roofs/Zip/ZipHome.html.

Insulation can be made from a variety of materials. Four main types of insulation include:

  • Rolls and batts — or blankets — flexible products made from mineral fibers, such as fiberglass and rock wool. They are available in widths suited to standard spacings of wall studs and attic or floor joists: 2x4 walls can hold R-13 or R-15 batts; 2x6 walls can have R-19 or R-21 products.
  • Loose-fill insulation — usually made of fiberglass, rock wool, or cellulose — comes in shreds, granules, or nodules. These small particles are blown into spaces using special pneumatic equipment. The blown-in material conforms readily to building cavities and attics. Loose-fill insulation is well suited for places where it is difficult to install other types of insulation.
  • Rigid foam insulation — typically more expensive than fiber insulation. Rigid foam insulation is very effective in buildings with space limitations and where higher R-values are needed. Foam insulation R-values range from R-4 to R-6.5 per inch of thickness, which is up to 2 times greater than most other insulating materials of the same thickness.
  • Foam-in-place insulation — can be blown into walls to reduce air leakage.

Adding insulation to your attic is one of the easiest and most cost-effective ways to make your home more comfortable year-round. "To find out if you have enough attic insulation, measure the thickness of the insulation. If it is less than R-22 (7 inches of fiber glass or rock wool or 6 inches of cellulose), you could probably benefit by adding more. Most U.S. homes should have between R-22 and R-49 insulation in the attic."

New products on today’s market provide both insulation and structural support, and should be considered for new home construction or additions. "Structural insulated panels, known as SIPS, and masonry products like insulating concrete forms are among these."

An old building technique that is regaining popularity is straw bale construction. Straw bale homes are constructed by stacking rectangular bales of straw and covering them with a plaster shell. "Straw bale walls are at least twice efficient as those from conventional stick-frame construction and will save you money on heating and cooling bills."

According to the DOE, only 20% of homes built before 1980 are well insulated. Accordingly, adding insulation may be the best way to improve your home’s energy efficiency. It can create a more uniform temperature year round, muffle sound from outside, save on your energy bills and help to further reduce your CO2 footprint.


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