THE WINTER Garden. The Orangerie. The Conservatory. The Sun Porch. The place in the sun for plants and people. Whatever you call them, rooms with masses of glass are becoming popular because they answer some of the major problems people face today.

Last winter's utility bills, not to mention this summer's, brought home to us the vital need to redesign our lives to collect or control the sun. From the White House to the housing development, solar energy is the word.But elaborate solar hardware is expensive. And the number of experienced, reliable and available solar designers and installers is limited.

While we're all standing first on one foot and then the other, waiting for government subsidies and advanced technology, there are other ways to plug in the sun. The first question to ask is: What did we do before - before cheap oil, before expensive equipment?

Bruce Anderson, Ron Alward and a number of other solar pioneers say that a greenhouse - call it the orangerie if it makes you feel posher - can make an effective passive solar collector. As effective, they say, as the elaborate solar heating systems with their fancy valves and pipes and whatcha-macallems. It is obvious to anyone who ever sat in a closed car in the sun how much heat comes through glass.

Unless you read mathematics and schematics, the concepts are easier to understand in the "soft" systems, as non-hardware unmechanical solar systems are sometimes called.

Here's the way it works. The basic necessity is a southern orientation. Due south is best, though some argue for slightly west of south. In any case, all the glass should be concentrated on the south wall. If there is a glass roof, it too should be sloped south. Because of the path of the sun, a south wall receives more light for a longer period of the day than any other direction. Not only that, because the winter sun is lower than the summer, it is possible by calculating the proper overhang to exclude sun from a south wall in summer, while admitting it in winter. The overhang could be an extension of the roof, or a trellis with a deciduous vine, or a canvas awning.

Now that you've let it in, how do you collect it? Back in the first two decades or so of this century, people built sun or sleeping porches: glass and wood extensions of the basic masonry house structure. They worked like a charm. Sun coming in the glass warmed the inside brick wall, the masonry acting like a heat sink. At night, the masonry re-radiated the collected warmth.

If the floor of the sunroom is a dark stone or brick or tile, there is more heat collected to warm the night. Don't put down rugs, they'll inside against the heat gain.

Here's the tricky part. On a cold but sunny winter day, not only can you bask in your solar heat trap, but by opening the door into the main house you can, without any more effort, duct in that warm air you've been collecting.

At night you close the door of the inner house to keep out the cold radiated from the glass. Another step that helps even more is to build insulated shutters to cover the glass wall at night.

With the proper positioning, adequate floor vapor barriers and other insulation, and a placement with good wind protection, such a room should not need auxiliary heat during the day, and be warm enough at night on that plants won't freeze. On very sunny winter days, in fact, it may be a bit too hot. And watch that your furniture doesn't fade.

A sunroom, of course, needs a large number of plants. Think not only of the cliche of coleus and the bounce of rubber trees, but also plants that are useful: patio tomatoes, edible peppers, dwarf orange and grapefruit trees, figs, and even, perhaps, bananas. Not only are the plants pretty, but their need for and ability to hold moisture will help humidify the room and make it more comfortable at a lower temperature.

A ceiling fan, one of the Casablanca kind, in winter will help send that hot air which always rises to the ceiling back down again where it's needed.

Cheerful colors on the furniture, and a white north wall will add to the apparent light and heat.

About those glass walls. Today there are a variety of combinations to help insulate the frames - some with metal outside and wood inside so the fram doesn't become a cold radiator. In every case, you must use at least double plan, insulated glass. Nothing else is economical today. Triple pane is better. If you already have double pane, think about adding storm windows as well. If the roof is to be glass or plexiglas, that must be doubled too. There are now even plastic insulated double wall and ceiling systems.

Ah but, you say, shaking your head, I can't afford oranges, much less an orangerie.

There are smaller answers.

Some of these solution are shown in the houses on the following pages, in great detail and full color. But here are the basic principles:

Any time you can, add windows to the south. (Where possible, close those on the eat and west in the summer or shad them with deciduous trees. Deciduous trees or vine-covered trellis can also be welcome shading devices for the south windows.)

Even a single window facing south can bring in a great deal of light and heat. Taller windows bring in more sun. Windows that go all the way to the floor are even better. Besides, with deep windows you don't miss seeing the cats go by or the early birds catching the worms.

Bay windows extending out, perhaps cantilevered, can work as mini-greenhouses, collecting morning and afternoon sun as well as midday if the center section faces south. Some very good looking contemporary bays have been designed with glass roofs.

Several greenhouse prefabricators, including Janco in Beltsville, Maryland, make window-sized greenhouses. Most home handypersons can install a prefabricated window greenhouse in an existing south wall. To make them really energy efficient, you should provide them with a double glazing, and if you can work out a way to leave in the original window as well, so much the better.

In any case, the new windows should have some form of night insulation. Wood shutters are trendy currently, but that's all right because they're about the best you can do. The ones with solid panels keep in much more air. Where possible, make them yourself with an insulating core between two panels. They can be stained, so they don't need much maintenance, or even painted with a picture or a design. To be inspired, go look at the ones by James Whistler in the Peacock Room of the Freer Gallery.

If you have enough wall on either side of the windows, you might consider having sliding shutters built. They can be designed to lap over each other where they meet for a better air seal. They will need a frame. If you're being fancy they can slide into pockets. The Victorian sliding doors that disappeared into the walls (usually between the parlor and the hall) are, without doubt, the world's most perfect doors.

There are, I admit reluctantly, other solutions to cold night windows.Quilts, for instance, don't work only on beds. Quilted curtains can be very effective, provided they are set within lambrequins or some other frame or method of holding them tight against the window on all sides. The more fiberfill or batting you put between the layers the better. Not as effective, but better than nothing, are lined curtains, or combinations of glass curtains and draperies. Shades, especially the kind with a reflective backing, can keep in a great deal of warmth. Bamboo blinds woven with fabric are not bad. Reflective transparent film, applied to east and west windows helps to some extent, but shouldn't go on the south windows because it excludes the heat rays.

Some of the best windows aren't in the wall at all, they're in the ceiling. Skylights are emerging as the most popular solar heating devices in Washington. In row houses, skylights are the best, and sometimes the only way to bring the sun's light and heat to the center of the house.

It has become almost an architectural cliche in Washington to use skylit atriums in the center of rowhouses. The center section, sometimes open even from the basement level, soars up to the roof's skylight - the larger the better. And of course, you have to have plants swinging down as sort of miniature hanging gardesn of Babylon. Such great light wells are very dramatic, turning dark scary row houses into sparkling spectacular indoor gardens, especially when they form the central court or plaza for the house. (Furnishings for such spaces seem to work best with a great deal of glass and chrome. Wicker and bamboo are good also, but they lack the glitter of glass.)

Skylights needn't be as big as all outdoors. Even the smallest skylights can go a long way toward brightening the corner where you are. Skylights in bathrooms, for instance, are the most satisfactory way of giving light without sight. Skylights over the bed are as romantic as the moon and as sexy as the stars. Skylights over the kitchen not only make your work easier but much more cheerful (See page 27/. Skylights in the study might even make you want to study. And then there is the Victorian necessity: the skylit staircase, an obvious but elegant solution.

Words of warning: skylights bring in more than light. They are a prime collector of solar heat. That's great in winter. Not so hot, or rather cool, in summer. The best skylights come with a shade that can be manipulated from below. The fancy skylights can also be opened to let out heat and vent the whole house with a chimney effect. Some skylights are also available with varying degrees of bronzing to cut down on the radiation.

There are other things to think about in climate-controlling your house:

White sand or gravel outside windows will help reflect light into the house.

Mirrors set just right will reflect not only good views but capture light.

Fountains, inside and out, will help cool hot summer days and in winter add welcome humidity.

Hanging plants can make a living curtain a window.

Closets, bookcases and other storage walls set against the north wall of the house are splendid insulation.

The old-fashioned vestibules, as so many Victorian houses had, are magnificent ways to keep the outside out in the winter. By closing the outside door before you open the inside one, you effectively keep the cold out. Ideally, all outside doors should open into this sort of air lock, and if they can be mini-greenhouses, well so much the better.

Ivy grown on the north wall, tall trees or hedges planted to the north, or even huddling your house in the lee of a neighbor's will help reduce the cruel north wind.

If you're buing a lot, look for a slope facing south so the house can be set down on the slope to protect if from the north.

Roofs should be white, for maximum reflectivity.

Decks, if they are actually roof gardens, can be covered with sod (provided your roof coating is impermeable so it won't leak.) John Wiebenson, an enterprising architect, once made a splendid roof garden and garden room in a rented apartment by stretching a plastic tent (actually sheet building plastic) up around and over, guyed with cables.

When you're planning to go south for your window, think about poking through the junk and wrecking yards to see if you can find handsome old French doors or workable sizes of tall two-over-two paned double-hung windows. If you find a stained glass section you can't live without, consider making it energy-efficient, as well as safer, by screwing a skin of the plexiglass over it.

If you have windows you especially like, the wavy old panes for instance, or just feel the need of more insulation, sheets of acrylic can be screwed into you wooden window frames. Or you can mount sliding track on the sill and put in sheets of sliding plexiglass.

It goes without saying but we'll say it anyway that all these openings should be heavily weatherstripped or you'll be sorry. Infiltration, as they call drafts these days, is a major cause of heat loss.

Let the solar energy be with you. Sunny days.