As fuel prices keep skyrocketing, talk keeps turning to ways of saving energy. The focus tends to be on heating costs, but a well-insulated house in which air leaks are sealed means money saved on summer cooling costs, as well.

What kind of insulation should you use? That depends on your house and all sorts of other factors.

First things first: Insulation material has pockets of trapped air that prevent heat from penetrating it. How well the material resists heat transfer is known as its R-value. The higher the R-value, the better the resistance.

Need to know: Some types of insulation are relatively simple for a do-it-yourselfer to install. Insulating blankets come as batts (precut pieces) or in rolls, and may have a paper or aluminum-foil facing that acts as a vapor retardant. Blankets are made of fiberglass (spun from molten sand and glass); rock wool, made of natural minerals; or slag wool, made from iron-ore blast-furnace slag, an industrial waste product. These types can be used in unfinished walls, floors and ceilings where the spacing is standard (studs or joists 16 inches or 25 inches on center), and where there are no obstructions such as water pipes, electrical wires or gas lines.

Reflective insulation includes foil-faced paper, polyethylene bubbles, and plastic film. It, too, fits well between studs and joists in unfinished spaces; foil-faced polyethylene bubbles are most suitable for places with obstructions.

How much is enough? The U.S. Department of Energy suggests measuring the thickness of the insulation. If it’s less than R-22 (7 inches of fiberglass or rock wool, or 6 inches of cellulose), you could probably benefit from more. Most U.S. homes should have between R-22 and R-49 insulation in the attic, for example.

Options, options: Increasingly popular is foam insulation. It’s typically made of polyurethane, has high R-values, doesn’t shrink or settle once in place, blocks air infiltration because it conforms to every nook and cranny, and offers a barrier to moisture. Rigid foam insulation, commonly made from fiberglass, polystyrene or polyurethane, comes in a variety of thicknesses with insulating values of R-4 to R-8 per inch. Indoors, it has to be covered with 1/2-inch gypsum board or other building-code-approved material for fire safety.

What will it cost? R-19 fiberglass batts are running about 55 cents a square foot; R-38 batts are $1.10, judging from an extensive Internet search. Cellulose insulation is running 12 cents a square foot, uninstalled.

An ounce of prevention: If you do the job yourself, dress appropriately. Wear a long-sleeved shirt and long pants, safety glasses, and a mask. Fiberglass in the eye can be painful; inhaled fibers can give you a sore throat or worse.

Don’t do this: Don’t use unfaced fiberglass insulation to seal air pockets, such as the spaces around plumbing and chimneys – the air will only pass through it. To act as a sealant, insulation has to be enclosed in something, such as a black or white plastic bag. The latter is better because it decomposes more slowly.