Dear Jim: My older house is chilly and I know it needs insulation throughout. Will adding insulation make me feel more comfortable as well as cut my utility bills? What’s the best type of insulation to use? – Marge S.

Dear Marge: It is generally understood that adding insulation to the walls or ceiling of a house will reduce monthly utility bills. The actual amount of savings for each home depend on the current level of insulation, your climate, efficiency of your heating-cooling system, and your utility rates.

You must have been doing your research on insulation because it will also make you feel more comfortable. If you are in a room at 70 degrees with no wall insulation, you may still feel chilly. This is because the exterior walls are cold and your body is losing its warmth by radiant heat transfer to the walls. During the summer, a hot wall makes you feel uncomfortably warm.

There really is not one “best” insulation to use in all locations in your house. For example, some effective attic insulation will settle if it is used in vertical walls. If there is just a slight amount of settling, the relatively small uninsulated void in a wall will waste a lot of energy.

What is important when selecting insulation is its installed R-value, not just its thickness. Some types of insulation have twice the R-value per inch thickness as others. Also, blown-in insulation can be fluffed up when installed, not necessarily intentionally, resulting in less true R-value.

Since you are planning to insulate your house to save money and conserve energy, you might consider an environmentally friendly insulation made of recycled materials. One good insulation is made from scrap bluejean material production. It looks similar to chopped up bluejeans in batt form. It is treated for fire safety and has an insulating R-value similar to fiberglass batts.

Fiberglass is made basically from sand so there is plenty supply. Some manufacturers use 25 percent recycled glass, so check the packaging if you prefer recycled products. Rock wool insulation is made from mostly waste products. It and fiberglass have an insulation value of about R-3 per inch thickness.

If the amount of space available for the insulation is limited, as in a masonry wall, injected foam is a good option. Some polyurethane foams have an R-value twice that of fiberglass, so only half the thickness is needed. The closed cell foam also creates its own vapor barrier and stops air leaks. Look for foam that uses no ozone-layer-damaging foaming agents.

Another option to minimize voids is called a blown-in-blanket method. This uses a blowing type of insulation, similar to attic insulation. An adhesive is mixed with it so it sets up in the wall quickly and will not settle.

Write for (instantly download – www.dulley.com) Update Bulletin No. 602 – buyer’s guide of 10 insulation manufacturers listing R-values, sizes, features, insulation selector guide, and a U.S. map showing recommended insulation levels. Include $3 and a business-size SASE, and send to James Dulley, 6906 Royalgreen Drive, Cincinnati, OH 45244.