Colorado’s Regulation 28 went into effect in 2022, and yet a surprisingly large number of commercial building owners in the state still haven’t started benchmarking, haven’t selected a compliance pathway, and aren’t sure what the December 2026 and 2027 deadlines actually require of them.
This guide covers the regulation clearly: who it applies to, what compliance actually means, how the four compliance pathways work, and what the real penalty exposure looks like for non-compliant buildings starting in 2030.
What Is Colorado Regulation 28?
Regulation 28 — formally titled “Building Benchmarking and Performance Standards” and codified as 5 CCR 1001-32 — is Colorado’s mandatory building performance standard for large commercial and multifamily properties. It was created by the Colorado General Assembly through HB 21-1286 (passed in 2021) and subsequently updated by HB 25-1269 (passed in 2025).
The regulation is enforced by the Colorado Department of Public Health and Environment (CDPHE) through the Air Quality Control Commission (AQCC). The Colorado Energy Office (CEO) provides technical assistance and administers complementary incentive programs.
In plain terms: if you own or manage a qualifying commercial building in Colorado, you must annually measure and report your building’s energy use and greenhouse gas emissions, and you must demonstrate by specific deadlines that your building meets defined performance targets.
Which Buildings Does Regulation 28 Cover?
Regulation 28 applies to commercial, multifamily residential, and public buildings at or above 50,000 gross square feet. This threshold applies to individual buildings, not portfolios — so a property owner with ten 40,000 sq ft buildings does not have ten covered buildings.
The following are covered:
- Commercial office buildings
- Retail and mixed-use buildings
- Multifamily residential buildings (apartments, condominiums)
- Hotels and hospitality properties
- Healthcare facilities and hospitals
- Educational buildings (private institutions; most state-owned buildings have separate requirements)
- Industrial and warehouse buildings above the threshold
- Municipal and government buildings (state-level requirements separate from Regulation 28)
Exempt categories include single-family homes, buildings under 50,000 sq ft, and federally owned properties (which have their own EPA energy mandates).
The Two Compliance Deadlines: 2026 and 2027
Regulation 28 establishes two performance compliance dates, based on building size:
| Building Size | Annual Benchmarking Deadline | Performance Compliance Deadline |
|---|---|---|
| 100,000+ sq ft | November 1 (annually) | December 31, 2026 |
| 50,000–99,999 sq ft | November 1 (annually) | December 31, 2027 |
These are hard deadlines. CDPHE is not telegraphing extensions, and HB 25-1269 refined rather than relaxed the program. Building owners waiting for the regulation to be modified or repealed are taking on substantial risk.
The annual benchmarking deadline (November 1) requires submitting your building’s energy use data through ENERGY STAR Portfolio Manager or another CDPHE-approved tool. This is separate from — and a prerequisite to — demonstrating performance compliance.
The Four Regulation 28 Compliance Pathways
This is where most building owners get confused. Regulation 28 doesn’t mandate a single approach. It offers four compliance options, and you choose the one that best fits your building.
Pathway 1 — Meet a Prescribed EUI Target
Your building’s Energy Use Intensity (site EUI, measured in kBtu per square foot per year) must fall at or below a threshold set by CDPHE based on your building’s primary use type. These targets are derived from ASHRAE Standard 100 benchmarks. If your building already performs well — especially newer construction or buildings with recent major upgrades — this is the simplest pathway. An audit confirms whether you meet it without any additional investment.
Pathway 2 — Achieve a Percent Reduction in Site EUI
Starting from your building’s 2021 benchmarked EUI as a baseline, you must reduce site EUI by 13% by the 2026/2027 deadline and by 29% by December 31, 2030. This pathway works well for buildings that have improved since 2021 or for which practical ECMs (lighting, HVAC, controls) can achieve the required reduction.
Pathway 3 — Meet a GHG Intensity Target
Similar to Pathway 1, but based on greenhouse gas emissions intensity (metric tons CO₂e per square foot per year) rather than EUI. CDPHE sets the target by building type. This pathway is often advantageous for buildings with on-site renewable generation or those on utility clean energy rate programs, where physical energy consumption may be high but carbon-attributed emissions are lower.
Pathway 4 — Achieve a Percent Reduction in GHG Emissions
Reduce your building’s total GHG emissions by 13% by your performance deadline and by 29% by December 31, 2030, compared to your 2021 baseline. Xcel Energy’s grid has been decarbonizing steadily — meaning some buildings are already achieving GHG reductions through utility grid improvements even without physical building changes. An audit models this.
What Does the Audit Actually Involve?
Many building owners ask whether the regulation requires a formal audit or whether benchmarking data alone is sufficient to declare a pathway.
The honest answer: benchmarking data alone is sufficient to select and initially declare a pathway. But demonstrating that your building will actually achieve compliance — especially under Pathways 2 or 4 where you’re projecting reductions from a baseline — requires an energy assessment to identify which measures will deliver those reductions and how.
An ASHRAE Standard 211-compliant energy audit:
- Establishes your current EUI and GHG baseline precisely
- Identifies specific Energy Conservation Measures (ECMs) with estimated energy and emissions savings
- Models all four pathways and recommends the most achievable one
- Produces the documentation CDPHE reviewers look for when evaluating compliance claims
We’ve seen buildings try to navigate Regulation 28 with Portfolio Manager data alone and hit compliance gaps they didn’t anticipate. The audit is the map.
What Are the Penalties for Non-Compliance?
Regulation 28 enforcement ramps up significantly starting January 1, 2030. Until then, CDPHE is focused primarily on benchmarking compliance and pathway selection.
Here’s the full penalty structure:
| Violation Type | First Offense | Subsequent Offenses |
|---|---|---|
| Benchmarking failure | Up to $577 | Up to $2,300 |
| Performance standard violation (2030+) | Up to $2,300 per 30-day period | Up to $5,800 per 30-day period |
| Annual Building Decarbonization Enterprise Fee | Required from all covered buildings starting 2025 | N/A |
The per-30-day structure for performance violations means a building that remains non-compliant through 2030 accumulates fines quickly. A building that misses the deadline and remains uncorrected for 12 months faces potential exposure of $27,600–$69,600 in fines before any remediation.
Colorado Energy Incentives That Reduce Your Compliance Cost
One underappreciated aspect of Regulation 28 compliance: the energy improvements that reduce your EUI and GHG profile often generate significant utility incentives that offset both audit and improvement costs.
Xcel Energy (the primary utility across most of Colorado) offers commercial rebates through its Energy Efficiency Programs for lighting retrofits, HVAC upgrades, variable frequency drives, building automation, and other qualifying measures.
Black Hills Energy serves commercial customers in southern and southeastern Colorado and offers parallel commercial efficiency programs.
Colorado C-PACE (Commercial Property Assessed Clean Energy), administered through the Colorado New Energy Improvement District, allows building owners to finance qualifying improvements through a property assessment — meaning no upfront capital required, and the obligation transfers with the property at sale.
In many cases, the combined value of utility rebates and C-PACE financing available for audit-identified improvements substantially exceeds the audit cost itself.
Next Steps for Colorado Building Owners
If your building is 50,000 sq ft or larger and you haven’t started benchmarking, that’s the first priority — you need 2021 baseline data established before you can declare a compliance pathway.
If you’re already benchmarking but haven’t selected a pathway or commissioned an audit, your next step is an energy assessment. Audit timelines typically run 6–10 weeks from engagement to final report.
We provide flat-fee audits for Colorado buildings statewide. See pricing → or request a quote for your specific building →.
For a deeper look at the four compliance pathways and how to choose between them, see our Compliance Pathways Guide →.