A federal judge on Tuesday narrowed the challenge to Denver’s recent restrictions on certain natural gas appliances from a collection of industry groups, noting some of the complained-about regulations were not in effect.

Last summer, trade associations representing homebuilders, restaurants, apartment buildings, hotels, manufacturers and fuel suppliers sued the city. They took aim at a portion of Denver’s municipal and energy codes generally aimed at replacing gas furnaces and boilers with electric equipment for commercial and multifamily buildings.

The plaintiffs broadly asserted Denver’s regulations would raise costs or reduce sales for their members. They argued the federal Energy Policy and Conservation Act, which enables the federal government to establish energy standards for covered appliances, overrode Denver’s local measures.

The Sierra Club moved to intervene in the litigation, citing its participation in crafting the energy regulations and its contention that Denver would not be exclusively focused on defending the environmental and health interests at stake. In May, U.S. Magistrate Judge Kathryn A. Starnella permitted the group to intervene.

The Sierra Club argued in favor of dismissing the lawsuit. It noted the plaintiffs were challenging three areas of regulation:

• 2023 standards related to fossil fuel, warm-air furnaces
• 2025 standards about exterior, gas-fired furnaces
• 2027 standards for gas-fired boilers

However, to date, only the 2023 policy was in effect.

“Unless and until Denver takes additional actions in the future to add the 2025 and 2027 standards to the Energy Code, those standards are not final and have no effect on the Industry Groups’ members,” wrote the Sierra Club’s attorneys.

The plaintiffs countered that a “Sword of Damocles” was hanging over them and, at “any moment,” the standards could take effect.

But in a Sept. 16 order, U.S. District Court Chief Judge Philip A. Brimmer agreed with the Sierra Club.

The 2025 and 2027 standards “do not represent a final action. A subsequent law must be passed before the standards become an enforceable part of the Energy Code, and there is no reason that the standards could not be modified before being placed into the Energy Code,” he wrote. “The Court finds that to rule on a standard that Denver has not yet made enforceable would entangle the Court in an abstract disagreement and would interfere with the deliberations of a government body that has not yet made a formalized decision.”

He acknowledged the plaintiffs may have to consider the possibility of additional gas appliance standards in their future planning, “but that alone is not a sufficient hardship,” Brimmer added.

Consequently, he dismissed the portions of the complaint challenging the not-yet-in-effect regulations. Brimmer otherwise found the plaintiffs brought their challenge to the 2023 standards within the required statute of limitations.

The case is Restaurant Law Center et al. v. The City and County of Denver.