The General Services Administration is putting the squeeze on federal employes in an effort to save up to $100 million in office rental costs.

For most government workers, an order sent out Friday from GSA Administrator Gerald P. Carmen will mean a little less elbowroom the next time the agency shuffles its workspace.

On average, federal workers will be asked to work in 135 square feet of space instead of 175 square feet.

Few will actually get the average, of course. Lower-grade employes will get considerably less, and higher-grade employes considerably more. GS grades 1 through 6, which are now supposed to get 60 square feet of space, will be afforded 45 square feet in new office layouts. Theoretically, that means 10 typists--desks, tables and all--would fit in a room 21 feet by 21 feet. Supervisors in the Senior Executive Service would be alloted 200 square feet, or an office slightly larger than 14 by 14 feet.

Carmen's order jumps the gun on a directive from the Senate Appropriations Committee, expected to be issued later this year, telling GSA and the Office of Management and Budget to establish a new space standard of 135 square feet per person.

"The establishment of a per-employe space utilization standard is a responsible way to reduce office space government-wide without seriously jeopardizing the mission of the affected agencies," a committee report said. "It is estimated that as much as $100 million per year could be saved if the more rigid space utilization standard were implemented and used as the basic criteria for assigning office space to federal agencies."

The panel, which said agency directors should make "tough management decisions" on office space allocation, commended Carmen for space reductions at GSA.

GSA has dropped from an average of 203 to 155 square feet per person over the past fiscal year. That's tighter than the Labor Department, where the average employe gets 183 square feet, but more spacious than the Defense and Treasury departments, where the average is 140 square feet.

Agency heads aren't subject to the space standards. Carmen, however, taking a tip from his Carter administration predecessor, has elected to use a 500-square-foot office down the hall from a 1,245-square-foot space used by other GSA administrators. The larger room is now used as an agency conference room.

With the help of a new branch of utilization experts, GSA this year has studied more than 400,000 square feet held by 15 agencies in the Washington metropolitan area and suggested reductions of 109,150 square feet. The biggest cuts were 24,000 square feet at the Consumer Product Safety Commission's offices at Westwood Towers in Bethesda and 22,000 square feet at the Federal Maritime Commission's offices at 1020 11st St. NW.

"We'll be very happy if we get one-third of the suggested reductions in each instance," GSA Public Buildings Commissioner Richard O. Haase said, noting that the changes must be carefully crafted so that they don't involve alterations to a building, which increases costs.

"This is a selling job," Haase said. "If we can convince agencies that we're serious, that we can save them and the government money, then they'll cooperate. In these times of tight budgets, agency managers just can't throw money away on unneeded space."