Energy saving suddenly is the magic word in home appliances and equipment.

Although lofty abstractions about conservation for future generations haven't stirred many consumers to action, rising utility bills have. The high cost of electricity and gas is a tangible and painful inspiration to conserve.

The current consumption of energy for residential purposes is staggering. It is estimated that the American homeowner uses 17 quadrillion BTUs of energy annually, roughly equivalent to 8 1/2 barrels of oil per day. More than half of those British thermal units go for basic heating and cooling.

It follows, therefore, that anyone who wants to save on the cost of energy at home should look closely at furnace and air-conditioning equipment. They'll find that consumer demand coupled with new, stiffer government standards are revolutionizing the alternatives for keeping warm in winter and cool in summer.

"Every manufacturer of heating or air conditioning is bringing out new products," reports Harold Hollub, president of Mid-Lakes Distributing, Midwest agent for a number of major companies.

"I would say the industry is where the automobile manufacturers were a while back. They have done as much as they could with existing models, and now they're going to have to go into actual redesigning of equipment. The initial changes increase effciency about 10 to 15 percent. The next step will require much greater expenditures on the manufacturers' parts.

"I see a lot of equipment changes coming along, but it means big investments. Many of the small- and medium-size manufacturers will probably go out of business. Only the big guys with a lot of money to throw in will survive," Hollub said.

Thermostats offer a singular opportunity for controlling heat and cooling. The variety is enormous -- from simple, pared-down basic models to elaborate electronic jobs that do just about everything except wash the dishes and change the baby.

One from Honeywell has a "brain," a programmable memory store with setback-setup commands, plus a liquid-crystal "information center" serving as a digital clock and thermostat status indicator. Another, from Home-tech Energy, is billed as a Management-Security System. It is a mini-computer providing for seven separate temperature-control zones, security functions and 16 control timers for sun shades, sprinklers and your morning coffee. The homeowner establishes energy priority levels and consumption-value sequences to monitor rates of electrical usage. The system then distributes usage to maintain the predetermined levels.

"As in the past with transistor radios or calculators, technology steadily improved and costs were reduced," Qualified Remodeler magazine noted in its recent special energy issue. "From their initial introduction, the newest generation of energy-saving thermostats are now well within the reach of any homeowner, and the cost-efficiency payback potential is outstanding."

Although the future is promising;, consumers will have to do their homework and pay attention to details to get the most of either existing or new equipment.

The equipment that does wonders for a neighbor could be a disaster in your home. "Deciding what is best for your home in heating, cooling or other types of equipment involves a number of factors," Hollub cautions. "It depends in part on your own particular house and your individual fuel bills.

"If your heating equipment is bad, I would certainly say you should replace it with something that is more efficient. But tearing out a perfectly good piece just to replace it with a new energy-saving model would be foolish.

"The new government EnergyGuide labeling isn't perfect, but it does serve as a basis for some comparison. Start with that and then compute what the costs of installation are; look at your fuel bills and relate what the saving would be to those bills. Ask yourself, 'How much can I save in a year vs. what the payback period will be?'"

Using the EnergyGuide label requires a little practice, too. The Energy Department offers a three-page guide to interpreting the new ratings. Basically, the process requires answering all the following questions:

Are the appliances comparable in size and features?

What is the price of the energy-efficient model (model with lower yearly cost or higher energy-efficiency rating)? And what is the price of the standard model (model with higher yearly energy cost or lower energy-efficiency rating)?

How often will you use the product?

What is your local energy rate? And, based on your local energy rate, how much will each model cost you to run yearly?

How long do you expect to keep the appliance?

After answering those questions, you can figure whether you are better off buying the mopre energy-efficient appliance by calculating the price difference between the two; estimating your annual energy-cost savings with the more energy-efficient model; calculating your energy-cost savings over the life of the appliance, and finally by figuring out how soon you can expect to recover your investment.