SYNOPSIS
Trade associations representing restaurants, home builders, hotels, apartments, and propane sued the City and County of Denver over its building codes, arguing that they are preempted by the federal Energy Policy and Conservation Act (“EPCA”).
WHY IT MATTERS FOR PUBLIC HEALTH
Buildings are one of the largest sources of greenhouse gas emissions in the United States. The combustion of natural gas also affects indoor air quality, emitting hazardous pollutants such as nitrogen dioxide, carbon monoxide, and benzene. It is understandable then that many state and local governments are seeking to curb emissions through building codes.
BACKGROUND
In 2021, Denver updated its building code to apply new requirements to existing commercial and multi-family buildings when space or water heating appliances are replaced.1 The requirements strengthen over time, so that by January 1, 2025 storage and instantaneous water heater replacements must be electric and for outdoor gas-fired warm air furnaces the primary replacement heating system must be electric with gas-fired furnaces providing at most supplementary heat.2 By January 1, 2027 replacements for gas-fired boilers used for space or water heating must meet 50% of the annual space or water heating needs through electric power.3 Exemptions are available for economic hardship or emergency replacement.4
The plaintiffs, many of which are large national trade associations, sued Denver arguing that these conditions on appliance replacement violate EPCA’s preemption of local regulation of covered products and do not qualify for an exception. EPCA generally preempts state or local governments from enacting energy efficiency or energy use standards for covered consumer products, like furnaces or water heaters.5 If a state or local building code would otherwise be preempted as an energy use or energy efficiency standard, there are seven criteria the code can meet to receive an exemption from preemption.6 The plaintiffs contend that Denver’s code does not qualify for the seven-factor exemption test. They also argue that Denver’s code violates EPCA’s industrial product preemption and fails to meet the exemption that the product not be required to exceed a specified minimum energy efficiency standard (ASHRAE/IES 90.1).7
A separate EPCA preemption challenge was filed against Denver and the State of Colorado in April 2024 by trade groups for landlords, hotels, and developers challenging the city’s building performance standard.
LITIGATION STATUS (Closed)
The case was filed on July 3, 2024 in the District of Colorado and has been assigned to Chief Judge Philip A. Brimmer. Denver filed an answer on July 29, 2024.
On May 1, 2025, the District of Colorado allowed Sierra Club to intervene in the case, in support of Denver’s regulations. The industry groups have until June 16, 2025 to oppose the Sierra Club’s motion to dismiss, which argues that the case has been brought too late to challenge the existing code changes, and too early to challenge the 2025 and 2027 changes. The Sierra Club filed its reply to the opposition on July 16, 2025, and the motion is now fully briefed.
On September 16, Chief Judge Brimmer filed an order on the motion to dismiss, granting Sierra Club's proposed motion to dismiss in part, and denying it in part. The order dismisses the complaint as to the requirements that have not yet been implemented into an enforceable law (the 2025 and 2027 requirements), but allows the complaint to move forward against the requirements that have been codified (the 2023 standards).
The plaintiffs filed an amended complaint on October 24, 2025. Denver filed a new motion to dismiss December 8, 2025, arguing that the challenged regulations are not preempted by EPCA and that plaintiffs don’t have standing. The briefing for that motion concluded on February 23, 2026.
On August 7, The Court granted granted the City and County of Denver’s Motion to Dismiss and Sierra Club’s Motion to Dismiss First Amended Complaint. The plaintiffs’ complaint is dismissed with prejudice and the case is closed.
1 Denver Mun. Code § 10-20 (2024).
2 Denver Mun. Code § 10-20(d) (2024).
3 Denver Mun. Code § 10-20(e) (2024).
4 Denver Mun. Code §§ 10-20(d)(8) & (e)(4) (2024).
5 42 U.S.C. § 6297(c).
6 42 U.S.C. § 6297(f)(3).
7 42 U.S.C. § 6316(b)(2)(B).