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Colorado’s New HVAC Emissions Standards

January 16, 2026

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Tom Poeling

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Tom Poeling is Director of Energy & Sustainability at U.S. Engineering Service. For inquiries, please reach him at tom.poeling@usengineering.com.

New emissions standards in Colorado took effect January 1, 2026, related to the selection and installation of gas-fired HVAC and water heating equipment on commercial projects. Colorado House Bill 23-1161 introduces Ultra-Low NOₓ (ULN) requirements that will affect the choices project teams make.

Non-compliance can lead to project delays, redesigns, cost overruns, and regulatory risk. At U.S. Engineering, we believe early awareness and thoughtful planning are essential to delivering compliant, cost-effective systems that serve our clients for the long term.

Here’s what project teams need to know. 

What’s Changing for Gas-Fired Equipment

Under HB 23-1161, all newly manufactured gas-fired furnaces and water heaters installed in Colorado must meet ULN emissions thresholds.

Gas Furnaces

(≤175,000 BTU/hr)

  • Maximum emissions: ≤14 ng NOₓ per joule of heat output

Gas Water Heaters

  • ≤75,000 BTU/hr: ≤10 ng NOₓ/J
  • 75,000–2,000,000 BTU/hr: ≤14 ng NOₓ/J

ENERGY STAR-certified equipment meets these ULN requirements, simplifying compliance for many projects.

Energy Efficiency: What the Law Does and Doesn’t Require

HB 23-1611 is primarily an emissions-focused regulation, not a prescriptive energy efficiency mandate.

  • The bill does not introduce new AFUE or energy factor minimums.
  • Compliance is still required with existing state appliance efficiency standards.
  • ULM limits naturally drive manufacturers toward higher-quality, cleaner-burning, and more efficient designs with advanced combustion controls.

Importantly, this is not a mandate toward electrification. Gas-fired systems remain viable when they meet the emissions requirements.

What This Means for Commercial Projects

These requirements apply to new installations and retrofits involving covered equipment.

Project teams should plan for:

  • Limited availability of non-compliant equipment after 2025.
  • Higher upfront costs for ULN-compliant models.
  • Longer lead times as manufacturers and suppliers adjust.

Equipment manufactured before December 31, 2025, may still be installed, but availability is expected to tighten significantly.

To avoid delays and cost impacts, we recommend acting now:

  • Review all projects scheduled for 2026 and beyond.
  • Update specifications to require ULN-compliant or ENERGY STAR-certified equipment.
  • Coordinate early with procurement teams.
  • Require manufacturer documentation verifying NOₓ emissions compliance.

Confirm compliance during submittals and commissioning.

Frequently Asked Questions

Does this apply to existing equipment?

No. Existing systems are not required to be replaced unless they are part of a planned retrofit or upgrade.

Can non-compliant equipment still be installed after January 1, 2026?

Only if it was manufactured before December 31, 2025. Inventory is expected to be limited.

Does this affect all commercial buildings?

Yes. Any commercial project installing gas-fired furnaces or water heaters within the BTU ranges must comply.

Are ENERGY STAR units automatically compliant?

Yes. ENERGY STAR certification satisfies ULN emissions requirements.

Our Energy & Sustainability team is available to support specification updates, equipment reviews, and compliance planning. If you have questions or need guidance, we’re here to help.