Washington's most famous house is white. Otherwise the city's touted white monuments in green parks are varying shades of buff or pink or gray. Elsewhere in town the predominant building colors come mainly from natural bricks or, in sections of the new downtown, precast concrete panels in hues that run from the innocuous to the dismal.

It takes a certain foolhardy courage or sense of humor, or both, to design and build a really white structure in this (mostly) fair city. Even so, two such buildings have appeared like eye-stopping apparitions this spring, and in places where they are sure to be noticed.

One of these, a little comercial building given a coat of Mediterranean white stucco, is located not too far from the real White House and, indeed, is referred to playfully by its arreverent architect as the "second 'white house' on Pennsylvania Avenue." The other, a low office-cumcondo building with an elegant covering of cloudy white Vermont marble, has landed like an improbable blimp on upper Wisconsin Avenue.

To say that these two unapologetically late modernist buildings depart from the norm of contemporary Washington architecture, and not only because they are white, is tt understate the case. This is not altogether a bad thing, although I certainly hope it is simply a trendlet, and not a geniune trend.

On the one hand the architects of these buildings thumb their noses at current speculative practice, stylistically mired in a bastardized International Style-Brutalist idiom. On the other, they make fun of the contextural politesse being practiced with great skill by many of the more design-oriented local firms.

The renewed interest in context--which can be roughly defined as the existing architectural character of a given place--is the healthiest aspect of the body of theory being advanced under the loose heading of post-moderism. Although it does not guarantee buildings of high esthetic quality (no formula does that), it prevents the kind of mindless destruction of the urban fabric begot by moderism's emphasis on the unique and the new.

By emphasizing the spirit of preservation and a special consciousness of place and history, it makes the street or the neighborhood or the city the focus of attention. The individual building and the personality of its architect become less important. By contrast our new white buildings stand out. The question is, should they?

It is haad to make this case for the commercial building at 2423 Pennsylvania Ave. NW, designed by Alfred H. Liu, except that, despite everything else, it is a little building and there's some fun in it. Most of its fancifulness clearly was intended; some, I suspect, was not.

The structure occupies a type of semiprominent position common in Washington, a curiously shaped corner formed by the angled intersection of L Street with Pennsylvania Avenue. Directly at the intersection there is a tiny triangular garden-park and then-bang--Liu's tight, blistering white, vaguely nautical little building, 5 1/2 stories high, constructed in part from the walls of two 3 1/2-story row houses.

In style, materials and color it is as shamelessly different as could be from everything else in the neighborhood, which consists almost entirely of larger, rather reticent apartment buildings of various colors of brick, a '50sstyle modern church and the cleverly massed, vaguely southern Californian Columbia Hospital for Women.

Liu says the style of the building is "high tech," and thus the double bands of white-sheathed oriel windows on two sides, the curved skylights that make something of an event out of the squeaky-tight setbacks of the upper floors, the punctuation points of exposed air ducts, painted brilliant red. Each of the facades is different--the park side of the building appropriately is the most playful, while the L Street side is a quiet curtain wall.

Still, the design as a whole is disjointed and excessively nervous. The architect tried to pack too much into his little building, pehaps because it is so self-consciously his, and the result is jarringly discordant. The white-white color needs toning down; as is it is simply, blatantly wrong for this location. I should say, however, that the building is not intended to be a free-standing structure; its ultimate effect will depend a lot upon what goes up on the parking lot next door. Liu certainly has created a challenge for that architect who, willy-nilly, must deal with Liu's new piece of the urban puzzle.

Except for its whiteness, which if anything is even more pronounced (in spite of the marble's gray veining), the building at 5025 Wisconsin Ave. NW, designed by the Washington office of Hellmuth, Obata and Kassabaum for the Amalgamated Transit Union, is almost as different from Liu's building as it is from its own immediate, undistinguished neighbors. (Architectural issues aside, the building, with two residential floors stacked atop three office levels, is urbanistically apt. That's the way it used to be along commercial strips. In this case, it took an incentive zone to get things back to normal.)

If there is excess here, it is an excess of consistency. with its heavy rounded spandrels, its rounded cornice, the teardrop curve of its entranceway and its tubular aluminum railing, the building is almost too much of a piece: a bulb, a blimp, an iceberg that looks like the ocean liner it sank. Still, it's a sleek design, neatly detailed. The building's none-toogentle upstaging of its neighbors on the strip is not upsetting because it is an area that can stand the ribbing.

But if the ATU building is an elegant oddity, it's no model for building in the city. One is enough. Perhaps the moral is that in Washington white houses belong in green pastures.