In scrapping most of the elements of a standby energy conservation plan, the Reagan administration not only managed to deep-six another Carter iniative, but also to demonstrate the ease with which it can change federal rules.

The Energy Conservation Act, passsed in 1979 at the urging of the former president, required the government to establish a standby federal emergency energy conservation plan short of gasoline rationing. All or part of the plan would be put into effect in the event of a severe shortfall of oil, such as followed the Arab embargo of 1973.

Last year, after holding hearings in eight states across the country, the Carter Department of Energy came up with interim and propoed rules for such a standby plan, which would include such measures as a shortened workweek, stickers to limit the days vehicles could be used, an odd day-even day program for gasoline purchases, office temperature restrictions, tougher speed limit restrictions and an extensive public relations effort to help get the nation to comply with all of this.

The Reagan administration, however, wants to let free-market forces handle energy shortages. According to the Feb. 23 Federal Register (page 13517), all except two of the Carter emergency conservation measures will be withdrawn. The public relations program will stay, as well as a minimum requirement for gasoline purchases, to prevent motorists from "topping off" their tanks.

The Reagan Department of Energy notice says that in light of the president's Jan. 28 decontrol of U.S. oil prices and production, "an unregulated market may now provide sufficient assurance of an orderly adjustment to any future energy supply interruptions."

During the public hearings on the proposed Carter plan, the new notice says, "many individuals and business representatives expressed their concern that several of the emergency energy conservation measures . . . would interfere excessively in their lives, were unnecessary restrictions and would impose costs far in excess of their benefits."

Those views didn't carry the day last year, but they clearly will now. No votes are taken in rulemaking.The views that prevail are the ones the rulemakers want, and the Reagan people are now the rulemakers.

Further evidence of that is in the questions DOE wants answered at an upcoming hearing on its withdrawal proposal:

"Is an unregulated market for petroleum and petroleum products the best approach to an energy supply interruption?"

"Would the various conservation measures . . . be counterproductive, imposing greater costs and administrative inconvenience than they may be worth?"

"Are there better approaches to handling any future energy emergencies . . . ?"

The new DOE leadership clearly still wants to be able to do something in a fuel crisis, for the notice says that "it wishes to note that any number of conservation measures might be activated if essential to managing any severe emergency supply shortfall."

The problem, DOE officials say, is that under the law those measures will have to be part of an already-approved, standby emergency conservation plan.

A hearing on the withdrawal proposal will be at 9:30 a.m. March 24 in Room 2105 at the Department of Energy, 2000 M St. NW, Washington, D.C. For more information call Kay Loomis, (202) 252-9319 .