Stanley Knock was fed up with paying high utility bills for his drafty, cold house at 1821 Redwood Ter. in Northwest Washington.

So, five years ago he began a campaign of making his 30-year-old house more energy efficient. Since then, he's invested a lot of sweat, had a lot of backaches and spent thousands of dollars, but Knock figures it was well worth it. Today, he figures his house is more valuable, costs less to heat and cool and is more livable.

"I have done everything that could be done," said Knock, who added that the measures he's taken have cut his energy consumption by one-third.

He did much of the work himself, from installing insulation in the attic to weatherstripping doors and putting an insulating blanket around his hot-water heater. But he's also had some major expenditures, such as $11,000 for 20 new, high-technology double-paned windows.

"Instantly, the comfort was better," said Knock of his house after the renovations. He said that his tighter house is now warmer with the thermostat set at 66 degrees during the winter than in the past when it was set between 70 and 72 degrees.

But he stressed that increasing the comfort level of his house was not the main reason for all his work and money. "It's an economic issue more than a comfort issue," Knock said. "It's whether you're going to invest money in your property to keep the utilities' bills down."

Knock's advice to other homeowners: Get to know your house, have an energy audit performed and beware of energy salesmen. "Cheaper is not the worst, and the most expensive is not the best," he said.

For many homeowners who are reminded that they have a leaky house every time their utility bill arrives, knowing where to begin to solve the problem is a problem in itself.

Ironically, thousands of Washington-area homeowners in the last several years have sought help in cutting their energy bills by turning to the very people that make the money supplying energy -- the utility companies.

"[Homeowners] want to do something about cutting energy costs , but they're not sure what the best thing is," said Duane Gautier, Potomac Electric Power Co.'s energy conservation manager, whose division offers free home-energy audits for all Pepco customers.

The Pepco energy-audit program, similar to one offered by Washington Gas & Light, helps consumers decide exactly what energy-saving steps they can take and how cost-effective those measures will be. Virginia Power "effectively ended" its audit program Jan. 1 to concentrate on lowering new-home energy costs, according to VP's senior energy services representative, John Oyhenart. The Pepco program, which has served 18,000 customers since 1978, provides for either sending a professional to a home for the audit or sending homeowners a detailed questionnaire, which is then run through a computer to come up with specific recommendations.

The audits evaluate an entire house, and make suggestions on everything from thickness of attic insulation to correcting leaky windows.

Gautier, who said that energy audits are still popular despite the stabilizing of energy costs, explained that most steps taken by homeowners are cost-effective and relatively inexpensive.

Joseph Anderson, conservation manager for Washington Gas, agreed and noted that the public's interest in cutting energy costs has been maintained through the constant bombardment of ads "by energy-equipment companies."

Washington Gas has conducted 9,000 audits since its program began in Maryland in 1981 and in the District and Virginia in 1984. Audits are free to District residents, but cost $15 for Virginia and Maryland customers.

Audits also are offered by so-called house doctors, but are generally more expensive, although many firms offer more comprehensive services than the utility companies.

So where does a homeowner begin? "Start with tightening air leaks," said Tom Feliu, producer of the Public Broadcasting Service show "A House for All Seasons," which is shown Saturdays on WETA and WHMM. Feliu, the former director of Denver's Energy Resource Center, said that while air leaks around doors and windows are important, homeowners should be most concerned with the area where the floor meets the exterior of a house.

Such leaks can be solved quickly by using a tube of silicon or acrylic caulk, he said.

Feliu, who believes that consumer interest in energy conservation is not as high as during the mid-1970s energy crisis, said weatherstripping hatch doors that lead to an attic is another simple yet important solution for preventing air leaks.

All of the experts contacted said most of the low-cost steps to conserve home energy can be performed by the homeowner.

Everyone agreed that double-paned or storm windows are essential for keeping the heat in and the cold out.

But for those on a limited budget, there are various alternatives. For example, consumers can buy a semi-rigid plastic product, costing about $6 per window, that can be removed in the spring and reused the following winter. Caulking around the window frames can be as important as the storm window itself, most experts added.

Other low-cost measures include weather-stripping under doors, cleaning and tuning furnaces yearly, installing water-flow controllers on shower heads that can save $15 to $40 annually, and installing insulation around the gap of a fireplace damper that can prevent precious hot air in the winter and cold in the summer from literally going up the chimney. (Such insulation must be removed before starting a fire.) Glass doors also make fireplaces tighter, but most experts agreed that fireplaces rob more heat than they supply.

For those who forget to lower their furnace thermostat before going to bed or heading off to work, experts recommend installing a $100 device that automatically will perform the chore. The timer unit also can be set to turn on at a specific hour each day.

Keeping window shades drawn at night to prevent heat loss is also urged, as is raising them during the day, especially for windows on the south side of a house. This turns windows into passive solar collectors by allowing the warm rays of the sun to heat a room.

Major home-energy renovations can be expensive, but well worth the investment, according to most experts.

Insulating ceilings and walls, replacing furnace systems, and installing storm windows might take longer for the money to be returned through energy savings, but they can add to a home's value and comfort level.

Many older homes in the Washington area have little or no insulation, according to the experts, who claim that the cost to add insulation usually can be paid back through lower energy bills in about five years.

Insulating the attic is the best place to begin, most agreed. Insulation can be blown in by a contractor or laid down by the homeowner, who generally can do it more cheaply and just as effectively. It will cost about 1 1/2 cents a square foot for every increase in the R-value, which measures how well a structure holds its heat. The higher the number, the better insulated the house.

Most experts said an R-30 rating is ideal for ceilings in the Washington area. Using the 1 1/2-cents formula, it would cost about $450 to insulate a 1,000-square-foot attic to an R-30 rating, said Feliu.

Wall insulation for wood-frame homes has a payback of about four years, said Feliu, who added that it's best to have a contractor blow in the insulation, which will cost about $1 per square foot of wall area. Feliu said that insulating walls of brick homes is hard to justify because of the added construction expense involved.

Another essential area for cutting energy costs is making sure appliances and heating equipment run efficiently, according to Henry Kelly, executive director of the Washington-based American Council for an Energy Efficient Economy.

"Even if your house is highly efficient, it doesn't do much good if your furnace is only 10 percent efficient," said Kelly. He explained that some new furnaces run 95 percent efficiently, which means that 95 percent of the heat generated in the furnace actually goes into the heating ducts, and is not lost up the chimney.

New furnaces can start at $750 plus insulation, and most experts advise buyers to select systems that have Annual Fuel Utilization Equivalency (AFUE) ratings in the 80 percent level. The AFUE rating is a label found on most furnaces or can be obtained from hardware stores or the dealer.

A recent booklet from the energy council on cutting costs by using appliances efficiently gives a number of simple tips for water heaters. For example, installing a $30 valve that helps prevent heat loss through the pipes can save $15 to $30 a year. A $30 automatic timer for electric water heaters that shuts off the heater at night can pay for itself in a year, as will spending $10 at a hardware store to wrap the tank with a special insulation blanket.

Pepco's Gautier said that the tank blanket will save $23 annually for homeowners with gas water heaters and $35 for electric heaters.