Most home-maintenance projects will save you money over time. But, only a few of them will produce an immediate and measurable return. Maintaining your home's energy envelope is one. The floors, walls, ceilings, exterior doors and windows of your home combine to make up its energy envelope. When it is properly maintained, your personal comfort level will increase. Finite control of heat and cold is achieved with insulation in walls, ceilings and floors and with infiltration control (sealing air leaks and making all exterior surfaces airtight).

If your home isn't well insulated, take care of it now. High winter fuel bills are on their way. Sealing gaps at windows and doors is an annual must do task. Weatherstripping comes in many of the following forms or in several combinations thereof: Vinyl, rubber, metal, foam and wood.

It doesn't take a workshop full of tools to install most types of weatherstripping. All you will need to install most are a screwdriver, razor knife and possibly a hacksaw. Depending on usage and financial limitations you can select from several weatherstripping configurations:

Metal V-strip, vinyl V-strip, integral vinyl V-strip, adhesive-backed foam (for doors and windows that don't get much use), hollow rubber beading on a metal flange, interlocking metal (should be professionally installed).

Metal V-strip weatherstripping is durable, long-lasting and easy to install. It comes with a pressure-sensitive adhesive backing that, except for cutting to length, allows for a tool-free installation. The V-strip is mounted on the doorframe at the location where it comes into contact with the face of the door when the door is in the closed position. The V-strip is flattened when the door is closed. Be that as it may, the built-in spring tension that causes the V-shape closes the gap between the door and the frame, keeping air from passing through.

V-stripping also is available in vinyl which is as good as the metal type. Vinyl V-stripping also is available in a type that is built directly into the door frame. The weatherstripping snaps into a groove in the doorframe. Press to lock it in place - no adhesive needed.

Adhesive-backed foam is installed in the same way and in the same location as V-style weatherstripping. Although adhesive-backed foam is inexpensive, it isn't durable. You won't be able to count on it to last an entire winter if you install it on a frequently used door.

Interlocking-metal weatherstripping is the most expensive and the best. Small metal flashings are placed at the door and frame. When the door is closed the metal flashings interlock. Interlocking weatherstripping is usually only installed at doors and casement windows. Both door and frame must be notched with a router. The special tools and the associated tedious installation make interlocking metal a number-one candidate for installation by a pro. Interlocking weatherstripping is installed completely around the perimeter of the door - top, sides and bottom. A special threshold is installed which interlocks with the metal flashing at the bottom of the door.

With the other types of weatherstripping that we mentioned, a door shoe is used at the bottom of the door. Here, the shoe is adjusted to close snugly against the threshold. Sometimes rubber weatherstripping is mounted on the door shoe and other times on the threshold. We like it when the rubber is on the door bottom. Mounted on the threshold, it tends to wear out more quickly as a result of foot traffic.

Regardless of the type of weatherstripping you use, you should check every opening to determine whether a problem exists. A lot of air passes through walls, ceilings and floors. There are easy ways to test for leaks: The candle or incense method, the wet finger method and the flashlight method. These tests are easy to undertake. Use them around:

Light switches; electric plugs; drain pipes; water pipes; heat registers; thermostats; wall and ceiling light fixtures; smoke detectors; floor plugs; door bell chimes; doors and windows.

The candle or incense method.

This is our favorite. It works every time. All you have to do is light a candle or some incense and hold it next to a suspect leak point. If a leak exists, the flame will flicker. If it is a calm day turn on all of the exhaust fans in your home. The negative pressure created will draw air in through gaps causing flame and smoke to flicker.

The wet finger method.

When air passes over water it causes the water to evaporate. Water cools as it evaporates. A wet finger will get cold when placed near a flow of air.

The flashlight method.

The flashlight method is used only at night. You'll need a friend to help one person outside, the other inside. A light is shined onto exterior walls, windows and doors. The person on the other side of the wall looks for traces of light passing through. Where there's light, there's leaks.