Colorado’s New Furnace Law (2026): What Denver–Boulder Homeowners Need to Know
Starting in 2026, new regulations in Colorado will change which types of gas furnaces can be sold and installed in homes. The goal of these updates is to reduce harmful emissions and improve air quality across the state.
If you’re a homeowner in the Denver–Boulder metro area, the key takeaway is simple: there’s no need to panic, but it is smart to stay informed and plan ahead.
Here’s what’s changing and what it means for your home.
What’s Changing in Colorado in 2026
Beginning January 1, 2026, all new gas furnaces sold or installed in Colorado must meet one of the following standards:
Ultra-Low NOx (ULN) certification
ENERGY STAR® certification
ULN furnaces are designed to produce significantly lower nitrogen oxide (NOx) emissions, helping improve local air quality. These furnaces emit 14 nanograms per joule (ng/J) or less of NOx, a major reduction compared to older models.
State agencies will enforce these standards, and installing non-compliant equipment after the deadline could result in penalties of up to $2,000.
The Good News: Existing Furnace Inventory Will Still Be Available
For Denver–Boulder area homeowners, this transition is expected to be gradual. Manufacturers anticipate that existing furnace inventory already in Colorado will last several months after the law takes effect, depending on demand.
That means:
You won’t be forced to replace your furnace immediately
Homeowners will still have options during the transition period
Planning ahead gives you more flexibility and peace of mind
What This Means for Homeowners
If your furnace is newer and working well, there’s likely nothing you need to do right now.
However, if your system is:
Over 10–15 years old
Requiring frequent repairs
Struggling to keep your home warm efficiently
…it may be worth starting the conversation sooner rather than later.
Planning ahead allows you to:
Understand new efficiency standards
Compare furnace options without pressure
Take advantage of rebates and incentives while they’re available
Important Timeline to Know
January 1, 2026:
All furnaces installed in Colorado must meet ULN or ENERGY STAR® standards with a minimum 95% AFUE (Annual Fuel Utilization Efficiency).July 31, 2026:
ENERGY STAR® Version 5.0 takes effect, increasing the minimum AFUE requirement to 97% for Colorado and other northern regions.
In addition, rebate programs through Xcel Energy and other state or federal agencies may change around this time, which could impact savings opportunities.
Why Colorado Is Making These Changes
Gas furnaces are one of the largest contributors to nitrogen oxide emissions in Colorado. These emissions affect air quality and public health, particularly in urban and high-traffic areas.
The updated standards are part of a broader effort to reduce pollution while encouraging more efficient home heating systems. Colorado will continue reviewing emissions standards through 2030, meaning additional changes are possible in the future.
Key Takeaways for Homeowners
There’s no immediate need to replace your furnace
Existing inventory should allow for a smooth transition
Early planning offers more flexibility and potential savings
Rebates and incentives may change after 2026
Replacing a furnace is a big decision — and it’s one that should be made with clear information, not pressure.
What’s Next for Denver–Boulder Homeowners
If you think you may need a furnace replacement in the next year or two — or you simply want to understand how the new law affects your options — our team at 1st Pro Services is here to help.
We’ll walk you through:
How ULN furnaces differ from older models
What efficiency levels make sense for your home
How to plan ahead based on your comfort needs and budget
👉 Have questions about the 2026 furnace law? Reach out anytime — we’re happy to explain your options.
