The time to find drafts in your home is when it's drafty

Don't think that just because the weather is cold you have to wait for next spring or summer to tighten up the energy efficiency of your house. The fact is, you can find drafts, cold spots, and air leaks much more easily when the weather is cold than in the warmer months of the year.

Not only can you save money immediately on every bit of insulation you add, every bead of caulking you apply, and every piece of weatherstripping you install, but you're also eligible for a credit on your federal income tax. The tax credit may expire in 1982. Insulation

Sheathing: For new homes and additions, insulating sheathing is like a fiberboard and sometimes replaces plywood on the walls. Styrofoam-brand sheathing, or its equal, is even more efficient.

Batts: More familiar is the blanket or batt insulation, which is stapled between the wall studs and floor and ceiling joists. Use a non-vapor-barrier type of insulation when adding more layers. If the insulation is installed with the vapor barrier on the wrong side, you can help to correct the mistake by slashing the vapor barrier so as to allow any moisture to pass through the insulation and dissipate through the roof vents.

Loose fill: Fiber glass, rock wool, and vermiculite are poured from bags to fill the space between the floor joists as well as the walls that have openings from the attic. Machines blow cellulose into wall and floor cavities.

Reflective: Aluminum foil sheets are also vapor barriers between studs and flooring. Reflective foil usually backs plasterboard sheeting.

Foam: This type of ureaformaldehyde insulation has received a bad name and is banned in some areas of the country because of problems with odor, shrinkage, and moisture.

Rigid: A sheet of rigid insulation already fixed to the back of sheets of wallboard can be nailed or glued easily to wall studs or basement wall furring strips. Uninsulated basement walls above the frost line are the same temperature as the outside air. If rigid insulation covers these walls, 11/2-inch floor joists on top of the sill plate and along the last joist on the foundation wall keep warm air in, cold air out. Caulking

Caulking also reduces drafts between the sill plate and the foundation of the house. Outside caulking is possible when the sun warms the surfaces on mild days.

Silicone: expensive, but it will last for years and adheres to most surfaces.

Latex: fast drying, smooths out better on painted surfaces than silicone, and cleans up with soap and water.

Polyvinyl acetate (PVA): good for painted and other surfaces.

Oil-based: poor because replacement is yearly.

Foam: fills large openings and acts as an insulation, but it's expensive.

Rope: easily fills cracks around basement windows and holds them in place. Furnace

Have a professional clean and check the furnace every year. On your own, clean out dust and debris with a shop vacuum, and change the filters to increase furnace efficiency for heating and cooling.

Oil or gas burners also need a professional service person. Making the flame too high or low may decrease the efficiency or even cause a fire. A soapy solution brushed around the joints reveals a good or poor connection; bubbles indicate leaks. Pipe wrenches used to tighten loose joints solve the problem of lost gas and a potential explosion.

Dirty thermostat contact points could mean furnace malfunction. A careful soft-bristled brushing prevents problems.

Most furnace blowers and motors have sealed bearings, but some require oil in cups or grease to fittings. Avoid overoiling and check all belts for snugness and slippage.

Duct tape applied to heating ducts reduces lost hot air. Rigid insulation fitted around ducts, cold and hot, becomes permanent.

Also, a special insulation wrapping for hot-water tanks and pipes can save up to 50 percent heat loss in one season. Fireplace

A fireplace with glass doors and special blowers becomes more efficient by as much as 30 percent. A glass door, for example, seals the opening, while a blower puts the warm air into the room instead of letting most of the heat go up the chimney.

When the fireplace is not in use, a tightly closed damper keeps the cold air out of the house, at least from this source.

A tight house saves money and energy.

Check with your local utility company for a low-cost, or even free, energy audit and find out what will give you the biggest payback for any money you decide to spend.