One of the things we hear often from facilities managers who’ve read Regulation 28 for the first time: “What exactly is a pathway, and how do I pick one?”
The regulation is genuinely flexible — four distinct compliance options, each designed for different building situations. The problem is that the flexibility creates decision paralysis. This guide cuts through that.
Why Four Pathways Exist
Colorado’s building stock is extremely diverse. A 1960s-era warehouse in Pueblo has a fundamentally different energy profile than a 2022-built Class A office tower in Denver’s Union Station district. A pathway that’s achievable for one building may be economically or technically impossible for another.
CDPHE designed the four-pathway structure so that building owners can select the compliance approach most appropriate to their building’s current performance, its physical constraints, and the capital they’re willing to invest.
Each pathway achieves the same underlying policy goal — reducing Colorado commercial buildings’ collective GHG emissions by 7% by 2026 and 20% by 2030 — but through different measurement and compliance mechanisms.
Pathway 1: Meet a Prescribed EUI Target
What it requires: Your building’s site Energy Use Intensity (EUI) — measured in kBtu per square foot per year — must be at or below a threshold set by CDPHE based on your building’s primary use type.
How CDPHE sets the target: The prescribed EUI targets are derived from national commercial building energy use data and adjusted for Colorado’s climate zones. The specific target for your building depends primarily on how ENERGY STAR Portfolio Manager categorizes your building’s primary use.
Who this works for:
- Newer buildings (2010+) with modern mechanical systems
- Buildings that have undergone major retrofits in the past 5–7 years
- Building types that are inherently low-energy by nature (certain warehouse and storage uses, for example)
- Buildings where the current benchmarked EUI already falls near or below the prescribed target
Sample scenario: A 75,000 sq ft Class A office building in Denver’s Cherry Creek neighborhood, built in 2018 with LED throughout, high-efficiency VRF HVAC, and an EMS. Current benchmarked EUI: 38 kBtu/sq ft/year. CDPHE’s prescribed EUI target for this building type in Colorado’s climate zone: 42 kBtu/sq ft/year. This building complies under Pathway 1 without any additional investment. The audit confirms and documents this.
The risk: If your building’s actual EUI turns out to be higher than the prescribed target, you’ve selected a pathway you can’t satisfy. An audit verifies this before you file a pathway declaration.
Pathway 2: Reduce Site EUI from a 2021 Baseline
What it requires: Reduce your building’s site EUI by 13% by your compliance deadline (Dec 31, 2026 for 100k+ sq ft, Dec 31, 2027 for smaller buildings), and by 29% by December 31, 2030. Both targets are measured against your building’s 2021 benchmarked EUI.
How the baseline is established: Your 2021 Portfolio Manager data serves as the baseline. If your building wasn’t benchmarked in 2021, CDPHE has guidance on establishing an alternate baseline year — but this requires documentation and CDPHE approval.
Who this works for:
- Buildings that were higher than average EUI in 2021 (meaning the 13% reduction target is reachable through practical improvements)
- Buildings where ECMs are cost-effective: aging lighting systems ripe for LED retrofit, older rooftop units approaching end of life, buildings without economizers
- Buildings where occupancy or operational changes between 2021 and compliance date will naturally reduce EUI
Sample scenario: A 90,000 sq ft retail power center in Aurora, built in 2002. Current EUI: 78 kBtu/sq ft/year. 2021 baseline EUI: 82 kBtu/sq ft/year. Target for 2027: 71.3 kBtu/sq ft/year (13% reduction). The audit identifies an LED retrofit (full Xcel rebate available) and economizer installation on 6 rooftop units that together reduce EUI to approximately 68 kBtu/sq ft/year — compliance with margin to spare, and a payback period of roughly 3.5 years on the improvements.
The nuance: If your building improved significantly between 2021 and today, your 13% reduction target may already be partially or fully met. Alternatively, if your 2021 EUI was already low, the 13% reduction may require substantial capital. The audit quantifies this before you commit to the pathway.
Pathway 3: Meet a Prescribed GHG Intensity Target
What it requires: Your building’s greenhouse gas emissions intensity — measured in metric tons of CO₂ equivalent (CO₂e) per square foot per year — must fall at or below a target set by CDPHE for your building type.
How GHG intensity is calculated: GHG intensity is derived from your building’s fuel consumption (electricity, natural gas, district steam, etc.) multiplied by the emission factors for each fuel. For electricity, the emission factor depends on your utility’s grid mix. Xcel Energy’s grid factor has been declining as coal plants retire and renewables come online.
Who this works for:
- Buildings with on-site solar or other renewable generation that reduces Scope 2 emissions
- Buildings on utility clean energy rate programs (Xcel’s Renewable*Connect or similar)
- Buildings in utility territories with clean grid mixes
- Buildings where the GHG intensity target is lower relative difficulty than the EUI target
The grid factor advantage: Xcel Energy’s annual emission factor for electricity has decreased significantly over the past decade. A building that runs the same amount of electricity as it did in 2021 but whose utility has added renewables to the grid will show lower GHG intensity in 2026 — even without physical building changes. This “free compliance” from grid decarbonization is real and worth quantifying.
Sample scenario: A 120,000 sq ft office campus in Fort Collins with 400kW of rooftop solar installed in 2023. Despite a relatively high site EUI, the on-site generation and Xcel’s clean grid factor combine to bring the building’s GHG intensity below the Pathway 3 target. An audit documents this with the precise calculation required for CDPHE compliance.
Pathway 4: Reduce GHG Emissions from a 2021 Baseline
What it requires: Reduce your building’s total GHG emissions by 13% by your performance deadline and by 29% by December 31, 2030, compared to the building’s 2021 GHG baseline.
How the baseline is established: Your 2021 fuel consumption data from Portfolio Manager, multiplied by 2021 emission factors for each fuel type, establishes the baseline in metric tons CO₂e.
Who this works for:
- Buildings with naturally high EUI profiles (healthcare, labs, hospitality) where hitting an EUI target is impractical
- Buildings that have added renewable energy since 2021
- Mixed-use buildings with multiple fuel types where the GHG reduction pathway is more achievable than EUI reduction
- Portfolio owners who can demonstrate aggregate GHG reductions across a portfolio of covered buildings
Sample scenario: A 180,000 sq ft hospital wing at Anschutz Medical Campus. EUI of 220+ kBtu/sq ft/year is effectively irreducible given 24/7 clinical operations. However, the hospital has enrolled in Xcel’s renewable energy program and installed co-generation, reducing its carbon-attributed emissions by 19% from 2021 levels. Under Pathway 4, this building complies — without any physical building improvements beyond the existing renewable agreements.
Choosing the Right Pathway: A Decision Framework
| If your building… | Consider… |
|---|---|
| Built post-2015, well-maintained, LED throughout | Pathway 1 first — you may already be below the EUI target |
| High EUI due to age, has obvious retrofit opportunities | Pathway 2 — ECMs should achieve the 13% reduction |
| Has on-site renewables or is on a clean utility rate | Pathway 3 — calculate whether grid decarbonization covers you |
| Healthcare, lab, or process facility with operational constraints | Pathway 4 — renewable procurement and grid factors may be your best option |
| Not sure | Get an audit — we model all four before recommending |
What the Audit Determines That Benchmarking Can’t
Benchmarking tells you where your building is today. An audit tells you which pathway you can actually achieve, what it will cost, and how to document it for CDPHE.
Specifically, the audit:
- Establishes precise 2021 baseline EUI and GHG data (not estimates)
- Calculates your current position against all four pathway targets
- Identifies specific ECMs with costs, savings, and implementation timelines
- Models each pathway’s achievability given your building’s physical constraints
- Produces the documentation CDPHE expects when reviewing pathway declarations
We’ve worked with building owners who selected Pathway 2 based on intuition, only to find during the audit that their building’s 2021 EUI was already so close to the Pathway 1 target that a small lighting upgrade made Pathway 1 simpler. The audit prevented them from over-investing in a compliance approach they didn’t need.
When Do You Need to Declare a Pathway?
CDPHE expects building owners to have a pathway selected and documented as part of the compliance reporting process. The specific reporting requirements for your compliance period will be outlined in CDPHE’s Regulation 28 reporting forms.
For most buildings, the practical answer is: you should have a pathway selected well before your compliance deadline — ideally at least 12–18 months prior, to allow time for any ECMs to be implemented and verified.
View our flat-fee audit pricing → or request a quote for your building →.
For more on Regulation 28 basics, see Colorado Regulation 28 Explained →.