AT A TIME when the exploding costs of imported energy are leading inflation, and when energy experts are in near-unanimous agreement that conservation offers the largest and lowest-cost near-term energy supply, the House of Representatives has agreed to fight in a House-Senate conference for a provision that will prevent the states from adopting one of the most promising conservation opportunities available.

The House set out, as did the Senate, repair an acknowledged mistake in the Energy Conservation Act of 1978: a provision that prohibits utilities from financing energy-conserving improvements in their customers' homes. The Senate simply deleted the offending provision. The House replaced it with pages of new language that make matters worse.

An aggressive program to improve the energy efficiency of existing homes and businesses could save the country the equivalent of 2.5 million barrels of oil a day by the mid- to late-1980s -- an amount equal to two-thirds of the oil now imported from the Persian Gulf states. But if individual homeowners can cut so much of their energy use by making energy efficiency improvements, why aren't more of them doing it? The answer is simple: the relatively high capital cost of the improvements; the time, hassle and difficulty of finding a bank loan; and, perhaps most important, the uncertainty of finding a contractor who knows what to do and who will do a quality job.

Utility financing is one way of solving all three problems. It is not the only way, but until an independent conservation service industry is built up, it is the only way now available. A properly regulated utility financing program does something else equally important -- it gives utilities a stake in energy conservation. Instead of seeing conservation as a threat, utilities can, under such a program, turn conservation into another way of making a profit.

The key to the feasibility of utility financing is that the necessary home improvements cost much less than the cost of providing new energy to meet growing demand. Specifically, the cost is equivalent to $20 per barrel of oil saved, while the average cost of new oil is already about $36 per barrel. The difference is so great that a utility can finance the home improvements with low-interest loans, and make a profit, and keep all its customers' bills lower than they would otherwise be -- and save engergy.

Such programs are not merely wishful thinking; they already exist -- in Oregon, California and elsewhere. But if the House position prevails, new programs like them would be illegal. None of the programs now in existence may be the best possible conservation program, but the best way cannot be found by forbidding experimentation in the states. Utility regulation should be left where it has traditionally been -- with the individual state public utility commissions. All Congress has to do is lift its previous prohibition and let the utilities help with the job.