Attics are among the least energy efficient parts of a typical home. They are generally not heated or cooled and often do not have sufficient ventilation or insulation. During colder months, the temperature in your attic will be approximately the same as the outdoor temperature. During the summer months, however, your attic can reach temperatures of 30 to 40 degrees hotter than the outside air.
Without the proper amount of insulation on the attic floor, a process known as heat transfer will cause the heated and cooled air inside the house to escape into the attic. This can result in significantly higher air conditioning and heating costs.
Insulation is relatively inexpensive and easy to install, and having the proper amount of insulation in your attic can save you thousands of dollars over the long term.
There are several types of insulation that can be used to reduce energy costs. Blown insulation is made from small pieces of fiberglass or cellulose and is blown into place using a compressor. Blown insulation is often made from recycled materials, and is fire resistant.
Rolled insulation, also known as batting, is made from fibreglass and is cut into various sized pieces which fit between the attic rafters. This type of insulation has a paper backing which allows it to be stapled into place as needed.
To determine how much insulation is needed in your attic it is necessary to understand R-values. The R-value of insulation is the resistance to temperature change, which is known as the thermal resistance factor.
The U.S. Department of Energy publishes guidelines for recommended R-values for different parts of the country. In general, the colder the climate the higher the R-value and the more insulation needed. For both heating and cooling the goal is to improve energy efficiency by keeping the air inside your home from escaping through small cracks, walls and ceilings. The amount of insulation put in your attic should be the amount needed to reach the recommended R-value for the region of the country where you live.
The map below shows recommended R-values for retrofitting existing wood-frame homes.
Measure the square footage (with X Length) of the attic. Then determine how thick the insulation should be to reach the recommended R-value. This will depend on the type of insulation used. For example, less rolled fibreglass insulation will be needed than blown insulation to reach a certain R-value.
Reaching the recommended R-value will make your home more energy efficiency and thereby reduce monthly energy costs. It will also place less of a demand on your HVAC system which help can prolong the life of your unit and help you avoid heating and A/C repairs.
An energy audit can tell you if you need more insulation in your attic and how much you need. An energy audit is the first step to making your home more energy efficient.
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