Peter Ellenbogen and Neal McCarty are local architects who got tired of having lunches with developers who keep their offices open but have nothing to build--no money, no customers. Last December, they opened Energy Works in Bethesda and began selling energy-saving items, from 6-for-59-cents insulation pads for electric switches to $6,000 passive-solar greenhouses. They wanted to put as many of these products as possible under the same roof and to offer customers expert advice in choosing what they need.

All the merchandise in the Energy Store promises to save money, at least in the long run. A "solar screen" fiberglass material to be stretched across windows reduces the need for air- conditioning; at 55 cents per square foot, Ellenbogen says, it pays for itself in two years. A $6.95 sheet of Mylar silver foil to be put under bedsheets reflects body heat and reduces the need for an electric blanket. Felt strips at 15 cents a yard stop the entry of cold air around doors and windows. And the efficiency of wood- burning stoves, priced between $250 and $900, was demonstrated last winter when a single stove heated the barnlike store.

"We spend our time talking to people," Ellenbogen says. He tells customers that "there is no one pill to cure their energy problems," but that they should consider "a whole bunch of small things"--such as caulking, weatherstripping, extra insulation, special threshholds--before they can expect "a collective improvement."

Ellenbogen says one day soon he wants to design and build a house that could be heated with a candle, "and I am not speaking metaphorically. I am talking about a combination of known details--not new inventions or exotic techniques. Most of energy-saving is just plain common sense, and a lot of it is plain good workmanship."

Ellenbogen, 47, is stocky, down-to-earth, solid. He is convinced that he is on to something big and exciting. McCarty, 27, is thin and tense, a fervent believer in energy conservation. The two have found that by capitalizing on the shortages of wood, metals and fossil fuels, they have hit on an ideal way to redirect their careers as architects. And they admit they enjoy dispensing advice to people who otherwise would not have consulted an architect about a drafty kitchen.

In addition, they are certain that scarcity is here to stay. "We are entering an era when the abundance of resources is over," Ellenbogen says. "Things we used to take for granted now have a value and a cost. We have to make careful decisions where we spend money."

Energy Works. 4915 Bethesda Ave., Bethesda. 656- 3670. Open 10 a.m. to 6 p.m. Monday through Saturday.