In a move that could prevent households across the country from saving billions of dollars in energy costs, the Department of Energy finalized a rule that prevents Obama-era efficiency standards for lightbulbs from taking effect early next year.

The efficiency standards, set to take effect on Jan. 1, 2020, sought to establish stricter energy efficiency regulations for some light bulbs, including a 45 lumen per watt minimum efficiency for incandescent light bulbs and higher efficiencies for LED and compact fluorescent bulbs.

By some estimates, the proposal could have saved individual households about $90 annually and reduced carbon dioxide emissions, a greenhouse gas that helps trap heat in the atmosphere, by 52 million metric tons.

“At a micro level, the Trump administration is hurting consumers,” said Jennifer Washburn, counsel on energy and environment for Citizens Action Coalition, a public policy advocacy group based in Indianapolis. “At a macro level, when we’re looking at systemwide cost and benefits of using less energy, he’s making it so that we’re going to have to be relying more from our power plants and produce more emissions.”

The standards fulfilled a requirement put in place by a 2007 law that would, among other regulations, ensure that light bulbs would meet the minimum efficacy standard of 45 lumens per watt by 2020.

The standards were introduced just a day before then President-elect Donald Trump was set to take office and were intended to fulfill that legal requirement.

“Lighting is a huge driver of greenhouse gas emissions in this country. Huge,” said Janet McCabe, director of the Environmental Resilience Institute at Indiana University. “We can make a big difference in terms of climate change pollution if we get more efficient in how we light our buildings.”

According to the Department of Energy, in 2018, the U.S. consumed 101.3 quadrillion British thermal units of energy, more than ever before. About 21% of that was due to residential use.

Nearly half of residential energy consumption, or 9.75 quadrillion Btu, is energy produced but lost during generation, transmission and distribution. That means companies must produce twice the amount of energy that will be used in order to meet demand.

More efficient light bulbs would reduce the amount of energy production required for residential use.

“(The rule) is keeping inefficient and inadequate technology on the marketplace,” Washburn told the Indiana Environmental Reporter. “Now they’re just going to prolong the inevitable and make it so that customers end up paying more on their bills rather than letting this new technology take hold.”

The Energy Department’s roll back already faces legal scrutiny.

The National Resources Defense Council, an environmental advocacy group, says the roll back is illegal because it violates “anti-backsliding” provisions of existing law that prevents the department from weakening existing standards.

“We will explore all options, including litigation, to stop this completely misguided and unlawful action,” said Noah Horowitz, director of the Center for Energy Efficiency Standards at the NRDC. “The Trump administration is illegally blocking the improved standards approved by a bipartisan Congress and supported by the lighting industry 12 years ago.”

In comments to the Department of Energy, the attorneys general of 15 states also said the Department of Energy would be violating the “anti-backsliding provisions” and added that the Trump administration would be violating the 2007 law that set the 2020 deadline.

The light bulb standard roll back is the latest attempt by the Trump administration to roll back efficiency standards.

The Trump administration has previously attempted to roll back efficiency standards for consumer products ranging from toasters to refrigerators.

The Department of Energy currently determines how companies test products for energy efficiency, energy use or estimated annual operating cost. But under the proposed 2019 Energy Conservation Program for Appliance Standards companies would be able to develop their own methods of testing for consumer products and submit their preferred testing procedure.

If the Department of Energy does not respond to the company’s proposal within 30 days, the company is allowed to operate using its testing procedure, no matter what it is, for up to 180 days.

Critics said the loophole could allow companies to claim their consumer products are more energy efficient than they are.

“Ultimately, the environment’s going to pay,” said Washburn. “We’re going to have more emissions because of this, and there’s uncertainty in the marketplace, which businesses and manufacturers certainly do not appreciate.“