A hundreds years ago, 75 per cent of all our energy came from wood. Now, wood provides only a small fraction of 1 per cent of our energy supply.

But, that fraction shows signs of growing fast. With the rising costs of traditional energy, sources and with the threat of gas shortages in certain parts of the country, more and more home owners (and some building owners) are investigating wood-burning stoves and central furnaces.

In New England, it's estimated that at least 30 per cent of the homes now use supplementary wood-burning stoves of furnaces for 50 per cent or more of their heating. And, in the Southwest, experiments are underway to use wood-burning devices with solar energy to power air conditioners.

For people who live in New England or the cold, North Central states, having a wood-burning supplementary or standby beating system can make a lot of sense. According to John Rummler, an architect and designer of wood-burning heating systems, "burning wood can cut your energy bill in half."

A lot depends on where you live - the availability and price of wood and the cost of regular energy supplies.

A heating stove can cost from $200 to $300 and, if you need an extra chimney for it, you can spend $200 to $300 more. A central wood-burning furnace that couples with your current heating system can cost anywhere from $1,200 to $2,200 installed. But this cost includes your hot water system as well.

If you live in a moderate climate area such as northern Florida or the Southwest, you can use a small, inexpensive stove. It's only used infrequently during cold snaps. Rummler warns that any stove has to be properly installed by an expert. Otherwise, you could create a fire hazard.

For colder climate areas where you want to use wood as an alternate fuel supply to bring down your overal heating costs, you can either install one or two larger stoves or install a central furnace.

You can get airtight, thermostatically controlled stoves that provide steady heat for 10 to 12 hours without reloading. But, long, slow fuel burns can create dangerous residue buildup. By using less wood, more oxygen and shorter burn time, you can get efficient heating with little or no residue. If you can store the heat in a hot water boiler system, you can also get less frequent refueling.

Central systems coupled with boilers can now use combinations of wood, solar and other fuels for a balanced energy supply. In some areas, wood suppliers are forming companies that keep you supplied on a contract basis (like the oil suppliers).

BOOKS AND BOOKLETS: Remember, "Your (energy) Meter is Running." That's the catchy title for a new booklet on how to save on your energy bills. It's written by the National Association of Realtors and can be picked up free at any of the 1,700 local boards of relators or at an individual realtor's office. According to one of the booklet's tips: If you see smoke in an oil burner, too much orange in the flame of a gas burner or hear your forced-air blower switching on and off, your furnace needs servicing. You could be wasting a lost of money.

Q. Are store and product coupons which we don't use worth money to some charitable organization? F.R., Burbank, Calif.

A. Many non-profit organizations can put coupons and bonus offers to work in various way. Some organizations help the elderly or handicapped with their shopping and use donated coupons to save money.

In some communities, the libraries or schools serve as clearing houses for stamps and coupons. You have to search. A good place to start s your local United Way or Red Feather headquarters.