According to the Energy Star program, you should add more insulation if the existing insulation is just level with or below the floor joists of your attic. If you cannot see any of the floor joists because the insulation is well above them, you probably have enough and adding more may not be cost-effective.

In addition, check to see if the insulation is an even thickness across the entire attic. Sometimes it can be thicker in the middle and then peter out toward the eaves. Attic insulation is measured according to its R-Value, which measures the insulation’s ability to resist heat flow. The higher the R-Value, the better the thermal performance of the insulation.

In many climates, the recommended level for homes is R-38. If you prefer more insulation, increase the R-Value. Insulation is made from different materials, including fiberglass, cellulose and rock wool. It comes in different forms.

Rolls and batts are some of the more commonly used types of insulation. Loose-fill insulation is a loose insulation with no backing that is usually blown into a space. Rigid foam and foam-in-place insulation are additional types of insulation.

The type of insulation used depends on where the insulation is needed and your budget. Certain materials are not applicable for particular uses, and typically insulation that provides a higher R-Value tends to be more expensive.

Examine the cost-effectiveness of the type of insulation being considered before application. You also can mix and match insulations depending on the application. The U.S. Department of Energy offers these additional tips with regard to insulation.

* Consider factors such as your climate, home design and budget when selecting insulation for your home.

* Use higher R-Value insulation, such as spray foam, on exterior walls and in cathedral ceilings to get more insulation with less thickness.

* Install attic air barriers, such as wind baffles, along the entire attic eave to help ensure proper airflow from the soffit to the attic. Ventilation helps with moisture control and reduces summer cooling bills, but don’t ventilate your attic if you have insulation on the underside of the roof. Ask a qualified contractor for recommendations.

* Be careful how close you place insulation next to a recessed light fixture — unless it is insulation contact rated — to avoid a fire hazard.

* Follow the manufacturer’s installation instructions, and wear the proper protective gear when installing insulation.

In addition to making a home more comfortable, insulation also can buffer noise, making the home more peaceful. Insulation can reduce noises from outside the home as well as absorb sounds from inside.

For insulation recommendations tailored to your home, visit the DOE Zip Code Insulation Calculator at http://http://web.ornl.gov/~roofs/Zip/ZipHome.html.