Shao W. Yuan has turned his expertise from heating to cooling.

Three years ago, the George Washington University engineering professor patented a method of collecting and storing summertime solar energy for winter heating.

Now Yuan has moved to the other end of the thermometer and patented something he calls NICE: a Natural Ice for Cooling Energy system that collects and stores wintertime ice for summertime cooling that he says could cut $500 from the cost of air-conditioning an average home in this area.

NICE and similar systems at Princeton, Argonne National Laboratory and Union Oil Co. of California use the same general principles, but each has its own twist.

Yuan first devised a system of water-filled solar collectors to capture the sun's heat in summer and transfer it to the earth surrounding plastic piping coiled underground. By the beginning of November, the temperature of the earth around the pipes has risen to 175 to 180 degrees Fahrenheit, warm enough to heat the water pumped through it all winter for heating and a source of hot water until spring.

He soon realized that underground storage and heat pipes could be used to cool instead of to heat and developed his NICE system.

Heat pipes filled with a medium such as liquid ammonia protrude above ground and extend into an underground container of coolant. This container, in turn, surrounds a reservoir of water. The warm coolant vaporizes the ammonia, and the vapor flows to the top of the heat pipe, where the winter air condenses it, creating a closed system.

The water reservoir's walls are insulated and flexible, permitting the expansion in volume as the water turns to ice.

During the summer, the ice in the container chills the coolant. A small, inexpensive pump circulates it through the household cooling system, replacing a conventional air conditioner compressor system.

Yuan estimates that, if his system were to become commercially available, it would cost about $3,000 to outfit the average home, with a savings in electricity use of about $500 a summer at current rates.

Right now a foil-covered tank about the size of a large barrel is connected with pipes and coils in the basement of one of GWU's laboratories, but Yuan hopes to put it outside next year to make ice during the winter of 1983-'84 so it can cool a test area the following summer.

The professor actually is developing two cooling systems. The NICE system is for areas cold enough to produce ice during the winter. His WISER (Winter Ice for Summer Energy Relief) system for warmer southern areas uses a refrigeration unit to produce ice during the winter for summertime cooling. Yuan says that this would cost less than standard air conditioning, partly because most of the electricity would be consumed during off-peak periods when rates are lower.

Argonne National Laboratory is using a system that reportedly differs from Yuan's NICE system mainly in the specific design of the heat pipes, while a cooling system developed by a former Princeton University physicist has similarities with both of Yuan's units. Theodore Taylor, now a consultant to Princeton and chairman of Taylor Kirkpatrick Inc., uses machines similar to the snow-makers at ski resorts to produce an ice pile in the winter from which ice-cold water will be extracted in the summer for cooling.

The first use of this system will be in an office building in Princeton's Forrestal Center complex owned by Prudential Insurance Co., which is financing the building. The ice will be made from December through the first of March in a plastic-lined earth berm reservoir. The reservoir is covered by an insulated building with open sides that is raised 20 feet above ground in the winter to let the cool air in.

Taylor Kirkpatrick has just started a project at the Kutter Cheese Factory in western New York about 20 miles east of Buffalo, Taylor said in a telephone interview from his home in Damascus. "The New York State Research and Development Authority is sharing the project's costs," Taylor said. "That project's first phase is completed -- the design of an ice pond."

He added that, although the system could be installed in an average home for about $1,000, "At the moment at least we have no detailed plans" to sell the system to homeowners or provide instructions for constructing one. "It's not automatic enough for most people," he said, noting that the machinery must be started at the proper time and the ice-making sprayer monitored, including rotating the sprayer head to keep the ice pile even.

Taylor sees the system as more valuable for commercial and industrial use, including dairy farms and plants that process frozen food.

Union Oil Co. of California produces ice at night to cool a new research center, and the Southern California Edison Co. is encouraging other customers to shift their electricity use to off-peak hours through this and similar projects, a spokesman for the utility said.