What new Washington office building has no hot and cold running water, but has two waterfalls, an ice-skating rink almost as large as Rockefeller Plaza in New York and soon will have a sibling of the Rive Gauche Resturant and the largest outdoor cafe in the Nation's Capital?

If you haven' guessed, take a stroll over to the corner of 17th and G streets NW, opposite the Old Executive Office Building and the White House. There, you will find the six-story, $41-million Federal Home Loan Bank Board building which opens next month, one of a newfangled breed of federal office buildings going up here and across the country.

The new Bank Board building and its ice rink - which opens within two weeks, before employees start arriving - is the first of a half dozen innovative federal office buildings being constructed or restored under the Living Buildings program of the General Services Administration, builder and manager of more than 10,000 of the nation's federal structures.

The new government-issue buildings, which will have boutiques, book stores, restaurants and dozens of shoops on their ground floors and will remain open at night, are designed to be livelier and more "public," says GSA administrator Jay Solomon.

Although the GSA innovations started quietly several years ago, the Living Buildings program officially was inaugurated only this week with the public opening of a dozen existing federal buildings around the nation, such as the Department of Commerce building at Pennsylvania Avenue and 14th Street. There were pottery and art shows in the Commerce lobby, Blue Grass groups in the cafeteria and music and theatrical shows in the auditorium, and GSA now has the welcome mat out for community events in federal buildings everywhere.

But new GSA buildings, such as the Home Loan Bank Board, will have a different look -inside and out - from the frab cement-glass boxes that now line many downtown Washington streets.

The overhanging balconies of the bank board building are designed not only to blend with the historic Winder office building next door, now being restored by GSA, but to break up the canyon walls of nearby office buildings. The overhanging ledges will have the added advantage of conserving energy, by allowing in low-angled winter sunlight and shading offices from the hot, high-flying summer sun. In warm weather, the ice rink will be converted to a pool with floating "duck boards" to sit and eat lunch on, with courtyard trees and two waterfalls to cool and calm those picnicking or sipping aperitifs nearby at the 200-seat outdoor cafe.

The cafe (an underground restaurant with a view of the bottom of one waterfall), a French restaurant overlooking the top of the waterfall and the courtyard will be operated by Georgetown's Rive Gauche Restaurant, or at least by the people who own the Rive Gauche. Tony Greco, a major shareholder in the well-knonw Rive Gauche, expects the food and wine to begin flowing next spring. The new restaurant, not yet named, will provide a companion for the Sans Souci, the only other major Frenceh restaurant near the White House.

Inside, the Bank Board itself, which regulates federally chartered savings and loan associations, has designed numerous ways to save energy and add variety to its employee's working habitat. The restrooms have one tepid water tap instead of hot and cold faucets (drinking fountains will continue to offer cold water) and there is task lighting, desk lights instead of endless banks of overhead fluorescent lights.

One reason GSA created the innovative bank board design is because it apparently wanted to make amends for hastily tearing down several historic buildings on the site, which the Department of Interior, several congressmen and the Advisory Council on Historic Preservation had hoped to preserve.

"We wanted to build something that didn't close at 5 p.m., something that contributed to the community . . . so we wouldn't be tearing down old and historic buildings like the Riggs Bank and replacing them with just another office building," said J. Wayne Kulig, GSA manager for the Bank Board project.

The 1829 Nichols Cafe, the 19th Century Winder annex and the 20th century Italian Renaissance-style Riggs Bank were razed in March, 1973, despite GSA assurances they wouldn't be and just one week after the Secretary of the Interior had declared them eligible for the National Register of Historic Places.

At the time, Rep. Fortney H. (Pete) Committee, belatedly filed suit in U.S. District Court here to block the demolition and called GSA's action "unthinkable . . . to destroy something that's really intended to be part of our national heritage . . . "

Judge Oliver Gasch asked GSA officials at the 1973 hearing, "Why did GSA go forward where there was such a determination by the Secretary of Interior?" and was told that GSA had determined it would take two months for the Advisory Council on Historic Preservation to decide on the buildings, creating a costly delay.

Because of what Kulig calls "the problems with the Riggs Bank," the bank board building was redesigned, the ice rink and courtyard proposed and the building's design changed to blend better with the 1848 Winder Building, where Lincoln came often to hear telegraph reports on Civil War battle s and to review troops from its balcony, GSA is now completing exterior restoration of the five-story Winder building, the largest office building in Washington in its day, and White House staff are expected to occupy the building when the interior is refurbished next spring.

Forgetting the "problems" with the demolition of historic buildings, GSA is pleased with its first new Living Building, partly because it has been finished ahead of schedule and almost $1 million under budget, but mostly because of its new design. "This is new for GSA," says Solomon, "our first building with out-leasing (ground-floor shops, restaurants, etc.), and there's a lot more coming."

Washington's old Post Office on Pennsylvania Avenue is to have shops and restaurants as well as government offices after its restorationby GSA, as is the old St. Louis Post Office and the old Custom House in New York City, all part of the Living Buildings program. CAPTION: Picture, Ice skating rink in courtyard of the new Bank Board building is partially completed. By Linda Wheeler - The Washington Post; Picture 2, The new $41-million Federal Home Loan Bank Board building at 17th and G Streets, NW, will have an ice rink and an outdoor cafe. By Linda Wheeler - The Washington Post