Insulation

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Introduction

Insulation can reduce energy usage in your home and business by up to 20%. Insulation provides a continuous thermal barrier minimizing heat flow through the walls, ceiling and floor. The result is increased comfort and reduced heating and cooling costs.

Technology Options

Ratings
Insulation is rated in terms of its thermal resistance, which indicates its resistance to heat flow. The higher the "R-value", the more effective the insulation. R-values of thermal insulation vary depending on the type of material, its thickness and its density. For multi-layered installation, the R-values of the different layers are simply added up. In short, installing more insulation on your building increases the R-value and the resistance to heat flow.

Types of Insulation
Although insulation can be made from a variety of materials, it usually comes in four types — batts, rolls, loose-fill and rigid foam boards.

  • Batts are made to fit between the studs in walls or between the joists of ceilings or floors. Batts are usually made of fiberglass or rock wool. Fiberglass is manufactured from sand and recycled glass, and rock wool is made from basaltic rock and recycled material from steel mill wastes. Batts are generally rated at R-3.2/inch.
  • Rolls or blankets are also usually made of fiberglass and can be laid over the floor in the attic. Their R values are similar to that of batts.
  • Loose-fill insulation (usually made of fiber glass, rock wool or cellulose) is blown into the attic or walls. Because it is blown in, loose fill can more effectively seal the area around wires, pipes or other obstacles that batts and rolls must be cut around, often leaving uninsulated spaces. Cellulose is usually made from recycled newsprint treated with fire-retardant chemicals. R-values range from R-2.2 to R-3.2/inch of loose-fill insulation. Watch video »
  • Rigid foam boards are made of poly-isocyanurate, extruded polystyrene (XPS or blueboard), expanded polystyrene (EPS or beadboard) or other materials. These boards are lightweight, provide structural support and generally have an R-value of R-4 to R-7/inch. Rigid board insulation is used in confined spaces, such as exterior walls, basements, foundation and crawl space walls, concrete slabs and cathedral ceilings. Foam insulation, like loose fill, can also be blown in. Foam insulation is generally more expensive than fiber-based insulations.

Where to Insulate
The easiest and most cost-effective way to insulate a home is to add insulation in the attic. To find out if you have enough attic insulation, measure the thickness of insulation. If there is less than R-22 (seven inches of fiber glass or rock wool, or six inches of cellulose) you could probably benefit by adding more insulation. Most U.S. homes should have between R-22 and R-49 insulation in the attic, depending on climate. If the attic has ample insulation and the home still feels drafty and cold in the winter or too warm in the summer, chances are you need to add insulation to the exterior walls. Wall insulation usually requires a contractor, but it may be worth the cost if you live in a very hot or cold climate. You may also need to add insulation to the walls or the floor above the crawl space.

To find the optimum levels recommended by the U.S. Department of Energy (DOE) for your general location, check the Energy Savers R-Value map. You can also determine optimum insulation for your specific needs, using DOE's interactive ZIP Code Insulation tool.

For more technical information on insulation, see:
  • The U.S. DOE Oak Ridge National Laboratory's Insulation fact sheet
  • The North American Insulation Manufacturers Association (NAIMA)'s website

Efficiency Benefits

A good insulating system includes a combination of products and construction techniques that improve a building's thermal performance, protects it against air infiltration and controls moisture. According to the U.S. Environmental Protection Agency (EPA), improving your insulation, combined with proper air sealing, can yield savings of up to 20% on your next energy bill. Exact money and energy savings depend on the previous level of insulation, your climate and the type of insulation you install.

Manufacturers

Advanced Fiber Technology , CertainTeed, Dow Chemical and Owens Corning are some of the manufacturers of ENERGY STAR qualified insulation. For a complete list, visit the ENERGY STAR website.

Purchasing Tips

  • Evaluate your climate. Use the U.S. Department of Energy's Energy Savers R-Value map and ZIP Code Insulation tool.
  • Evaluate your space. The type of insulation you use will be determined by the nature of the spaces in your home or building that you plan to insulate.
  • Check the label before you buy. A good insulation label should include:
    • type of insulation material
    • R-value (measured at 75°F)
    • types of spaces that can be insulated
    • safety precautions in application and use, including any fire hazard related restrictions
    • quantity in the package
    • name and address of the manufacturer or distributor
  • Conduct an energy audit. Consider hiring a contractor to do an energy audit of your building. An audit can identify the amount of insulation that needs to be installed. Many utilities also provide this service, often at no charge.
  • Hire a contractor. To make sure you insulate your home or building correctly, hire a contractor to do the work, especially if you are installing wall insulation in existing walls. Visit California Building Performance Contractors Association for help in finding a home improvement contractor.