How does insulation work?

To understand how insulation works, let's review how heat enters or leaves your home.
With utility rates soaring, one of the best ways to save money is by reducing the amount of energy needed to heat and/or cool your home. The U.S. Department of Energy estimates that proper insulation can save you 20% on your heating and cooling bills.

To understand how insulation works, let's review how heat enters or leaves your home.

Heat naturally flows from warmer to cooler spaces. Whenever there is an imbalance between the temperatures in adjacent spaces, the warmer air attempts to move toward the cooler air. In the summer, the hot air outside attempts to move to the cooler air inside your home. In the winter, the warm air inside your home tries to move outside. In addition to moving inside/outside, warm air will move through unheated areas of your home, such as attics, garages, and basements.

Now we understand that heat flows from warmer to cooler places. The most obvious sources of heat include the sun and burning fuel, but heat in your home is also produced by people, animals, lights, and appliances. There are three ways that heat moves:
  • Radiation: heat transfer through invisible light waves. An example of radiated heat is the heat you feel when you stand near a campfire.

  • Conduction: transfers heat through objects that are in direct contact. Boiling water is an example ? the stove burner heats the pan, which then heats the water.

  • Convection: heat transfer via the flow of fluid. Cooking vegetables in boiling water or a steamer is an example of convection heat.
Insulation slows down the transfer of heat inside/outside your home. It forms a barrier that absorbs heat, but it cannot block the flow completely.

The better the insulation, the less your furnace or air conditioning will have to work, which in turn lowers your monthly home energy bill. Insulation is rated in terms of its thermal resistance, or resistance to heat flow. This rating, called its R-value, is based on the type of material, thickness, and density. The higher the R-value, the greater the level of insulation.

In addition to saving on your heating and cooling bills, insulation also reduces the amount of noise that transfers between rooms. This noise-reducing benefit is especially desirable when little Johnny, your aspiring drummer, decides to perfect his technique through hours of determined practice.

Different situations ? climates, rooms, structure of home ? require different types of insulation. For more information on where to install insulation, how much insulation you need, and the different types of insulation, please read "What Kinds of Insulation Are Available?" and contact a recommended insulation pro in your area.

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