If you manage commercial or multifamily properties in Colorado, Regulation 28 is now one of your core compliance obligations. The Colorado Department of Public Health and Environment (CDPHE) began active enforcement cycles in 2025, and the next hard deadlines—December 2026 for Tier 1 buildings and December 2027 for Tier 2—are approaching faster than most property managers expect.
This checklist is designed for property managers who own or oversee multiple buildings and need a structured, repeatable process. It covers every stage from initial building classification through final reporting, with notes on documentation, contractor selection, and available financial incentives.
Before diving into the checklist, two things to understand about how Regulation 28 works: First, compliance is measured per building, not per ownership portfolio. Second, the regulation does not prescribe a single method—there are four compliance pathways available, and the right one depends heavily on your building type, current energy performance, and capital budget.
Phase 1: Building Classification and Deadline Mapping
Step 1: Identify All Buildings Over 25,000 Square Feet
Pull your portfolio and flag every building at or above 25,000 square feet of gross floor area. Buildings below that threshold are currently exempt from Regulation 28.
For mixed-use properties, calculate gross floor area across all uses—retail, office, residential, parking if conditioned. If a building was recently expanded or renovated, use the post-construction square footage.
Step 2: Assign Each Building to a Tier
| Tier | Gross Floor Area | Compliance Deadline |
|---|---|---|
| Tier 1 | 50,000 sq ft and above | December 31, 2026 |
| Tier 2 | 25,000–49,999 sq ft | December 31, 2027 |
For each building, document:
- Gross square footage (from certificate of occupancy or as-built drawings)
- Primary occupancy type (office, retail, warehouse, multifamily, hotel, etc.)
- Tier assignment and compliance deadline
- Current owner of record (the legal entity responsible for filing with CDPHE)
If you manage properties for third-party owners, confirm in writing who holds compliance responsibility. The regulation places obligations on the building owner, but owners frequently delegate operational responsibility to property managers. Get that delegation documented before CDPHE starts asking questions.
Step 3: Pull the Applicable EUI Target for Each Building
Energy Use Intensity (EUI) is measured in kBtu per square foot per year. Regulation 28 sets EUI targets by occupancy type. If your building meets or beats its target, it qualifies for the EUI compliance pathway—the most straightforward path for well-performing buildings.
Common EUI targets under Regulation 28:
| Building Type | EUI Target (kBtu/sq ft/yr) |
|---|---|
| Office | ~50 |
| Retail / Grocery | ~60 |
| Warehouse / Distribution | ~30 |
| Multifamily (residential) | ~40 |
| Hotel / Lodging | ~70 |
| K–12 School | ~50 |
| Healthcare (outpatient) | ~120 |
For a deeper breakdown of targets by building type and how EUI is calculated, see our full guide: EUI Targets Under Colorado Regulation 28.
Note that targets vary by climate zone and some occupancy subcategories. A 300,000 sq ft Class A office tower in Denver has a different baseline than a suburban flex office in Colorado Springs. Pull the specific target for each building, not a category average.
Phase 2: Baseline Energy Data Collection
Step 4: Establish a 12-Month Energy Consumption Baseline
CDPHE requires building owners to demonstrate current energy performance, which means you need 12 consecutive months of energy data for each building. That data typically comes from utility bills—electricity, natural gas, and any other fuels (propane, district steam, etc.).
For buildings you’ve managed for at least a year, pull all utility invoices for the most recent 12-month period. For recently acquired buildings, request 12-month billing history from Xcel Energy, Black Hills Energy, or whichever utility serves each property.
Document:
- Total electricity consumption (kWh)
- Total natural gas consumption (therms or ccf)
- Any other fuel types
- Gross conditioned square footage (not parking, not unconditioned storage)
- Primary occupancy category
Convert all fuel types to kBtu using standard conversion factors (1 kWh = 3.412 kBtu; 1 therm = 100 kBtu) and divide by gross conditioned square footage to calculate current EUI.
Step 5: Enter Building Data into ENERGY STAR Portfolio Manager
CDPHE’s reporting system is integrated with ENERGY STAR Portfolio Manager, the EPA’s free benchmarking platform. Every covered building needs a Portfolio Manager account with accurate energy data before you can file a compliance report.
If your buildings are already benchmarked under the Denver or other local benchmarking ordinances, this step may already be done. Check that:
- Building square footage is correct and matches your Regulation 28 records
- Occupancy type is correctly categorized (the ENERGY STAR category determines which EUI benchmark applies)
- Utility meters are connected (automated meter data pulls reduce manual entry errors)
- The reporting year aligns with what CDPHE expects
For multifamily buildings, note that whole-building energy data may require a data release agreement with Xcel Energy. Start this process early—utility data sharing agreements can take 4–6 weeks to activate.
Phase 3: Compliance Pathway Selection
Step 6: Evaluate Each Building Against the Four Pathways
With baseline EUI in hand, you can evaluate which compliance pathway is realistic for each building. The four options:
EUI Target Pathway: Building demonstrates its current EUI is at or below the CDPHE-published target for its occupancy type. No capital investment required if the building already performs well enough.
Prescriptive Measures Pathway: Building implements a defined set of energy efficiency measures regardless of resulting EUI. CDPHE publishes lists of qualifying measures by building type. This pathway works well when buildings are starting from a high EUI and owners prefer predictable scope over uncertain outcomes. See Regulation 28 prescriptive pathway requirements for the full measure list.
Performance Score Pathway: Building achieves a minimum ENERGY STAR score (typically 50 or higher, depending on occupancy). Useful for building types with well-established ENERGY STAR scoring models.
Custom Pathway: Owner develops a site-specific compliance plan with CDPHE approval. This pathway exists for buildings with unusual occupancy mixes, historic preservation constraints, or situations where standard measures are technically infeasible.
For each building in your portfolio, document:
- Current EUI and distance from target
- Most likely compliance pathway
- Estimated capital investment required
- Whether pathway requires CDPHE pre-approval (custom pathway does)
Step 7: Identify Buildings That Need an Energy Audit
If a building’s current EUI is well above its target and you’re uncertain which measures will deliver the required reductions, an ASHRAE Level 2 energy audit is the right starting point. The audit identifies specific energy conservation measures (ECMs), estimates their savings potential, and gives you the data to choose a pathway with confidence.
Buildings where an audit is typically necessary:
- Any building pursuing the EUI target pathway that is currently 20%+ above target
- Buildings over 100,000 sq ft where capital investments could be $500,000 or more
- Buildings with aging HVAC systems, no building automation system, or significant envelope deficiencies
- Buildings where the prescriptive pathway list doesn’t clearly apply
Buildings where an audit can sometimes be skipped:
- Already-benchmarked buildings with current EUI below or near target
- Buildings where recent capital improvements already meet the prescriptive list requirements
- Small Tier 2 buildings pursuing the prescriptive pathway with straightforward measure lists
Phase 4: Implementation and Documentation
Step 8: Prioritize Xcel Energy Rebates and Incentives
If your buildings are served by Xcel Energy (most of the Denver metro, Boulder, Fort Collins, Colorado Springs areas), the utility offers significant financial incentives for qualifying energy efficiency improvements. Xcel’s commercial rebate program offers up to $200,000 per building for qualifying measures including:
- HVAC equipment upgrades (chillers, boilers, rooftop units, variable frequency drives)
- Lighting retrofits (LED upgrades, lighting controls, daylight sensors)
- Building envelope improvements (insulation, window upgrades)
- Building automation and energy management systems
Key points for property managers:
- Rebates must be pre-approved before work begins—don’t install equipment and then apply
- Pre-approval applications can take 4–8 weeks to process
- Rebate amounts are tied to projected energy savings, not equipment cost
- Xcel’s Colorado Energy Office program also offers low-interest financing for measures that don’t fully qualify for rebates
For large portfolios, Xcel has account representatives who specialize in commercial customers with multiple buildings. Request a portfolio-level consultation rather than applying building-by-building.
Step 9: Sequence Work Across Your Portfolio by Deadline and ROI
With Tier 1 buildings due in December 2026 and Tier 2 in December 2027, construction sequencing matters. A few guidelines:
- HVAC replacements and major retrofits typically require 3–6 months from contractor award to commissioning. For Tier 1 buildings, any major HVAC work should be awarded by mid-2026 at the latest.
- Lighting retrofits and controls projects are faster (1–4 months) and can often be completed closer to the deadline.
- For buildings pursuing the EUI target pathway, improvements need to be in operation long enough to demonstrate the EUI in the compliance reporting period.
Create a project schedule that maps each building’s required actions to the available construction window, contractor capacity, and rebate application timelines.
Step 10: Maintain a Compliance Documentation File for Each Building
CDPHE’s enforcement approach relies on owner-submitted compliance reports, but enforcement audits can request supporting documentation. For each building, maintain a file that includes:
- Building profile (address, square footage, occupancy, owner of record)
- 12 months of utility bills used for baseline calculation
- ENERGY STAR Portfolio Manager account information and data sharing agreements
- Energy audit report (if applicable)
- Contractor invoices and completion certificates for all ECMs installed
- Equipment submittals and warranty documents for replaced equipment
- Any CDPHE pre-approval letters (required for custom pathway)
- Xcel Energy rebate application and approval letters
Keep this file organized and accessible. If you manage properties for third-party owners, provide them with a copy and retain one yourself.
Phase 5: Reporting and Filing
Step 11: Know the CDPHE Reporting Process
Regulation 28 compliance is demonstrated through CDPHE’s online reporting portal, which pulls energy data from ENERGY STAR Portfolio Manager. The filing covers:
- Building identification and ownership information
- Selected compliance pathway
- Current energy performance data (EUI or ENERGY STAR score)
- Documentation of completed measures (for prescriptive and custom pathways)
- Attestation by building owner or authorized representative
Property managers who are authorized to file on behalf of building owners need written authorization on file with CDPHE. Set this up before the filing deadline, not the week of.
Step 12: File Before the Deadline—Not On It
CDPHE’s online portal historically experiences traffic spikes at deadline. Submit reports at least 30 days before the December deadline for your tier.
More importantly, if you discover a compliance problem—a building that won’t meet its pathway requirements by the deadline—you need time to engage CDPHE about options. CDPHE has provisions for good-faith compliance efforts and can sometimes grant extensions for buildings with documented progress. Those conversations go much better when you initiate them before the deadline, not after.
Penalties for Non-Compliance
The penalties for Regulation 28 non-compliance are significant. CDPHE can assess up to $2,000 per day for each day a covered building remains out of compliance after the deadline. For a Tier 1 building that misses the December 2026 deadline and doesn’t come into compliance until March 2027, that’s roughly 90 days × $2,000 = $180,000 in potential penalties.
Penalties accrue per building. For property managers with five non-compliant Tier 1 buildings, exposure is up to $900,000 for the same 90-day window. That’s not a theoretical risk—CDPHE’s enforcement capacity has grown substantially with the addition of BPS enforcement staff.
Common Mistakes Property Managers Make
Waiting for tenants to act: In multi-tenant buildings, tenants control their own energy use but the building owner holds the compliance obligation. Don’t wait for tenants to change behavior—focus on base building systems (HVAC, lighting in common areas, envelope) that you directly control.
Confusing Portfolio Manager benchmarking with Regulation 28 compliance: Entering data in Portfolio Manager satisfies benchmarking requirements but is not the same as filing a Regulation 28 compliance report. They are separate filings through different processes.
Underestimating audit-to-implementation timelines: An ASHRAE Level 2 audit takes 4–8 weeks. Rebate pre-approval takes 4–8 weeks. Construction takes 1–6 months. A building that starts the audit process in January 2026 can make December 2026—but a building that starts in July 2026 almost certainly cannot.
Applying the wrong EUI target: Building type categorization in Portfolio Manager affects which ENERGY STAR score and EUI benchmark applies. An office building with significant retail on the ground floor may need to be filed as mixed-use, with a blended target. Get the occupancy classification right before calculating compliance.
Your Next Step: Get an ASHRAE Level 2 Audit Scheduled
For most buildings over 50,000 square feet that aren’t already below their EUI target, an ASHRAE Level 2 energy audit is the critical first step. It identifies what’s achievable, quantifies the cost of each improvement, and gives you the basis to select the right compliance pathway with confidence.
The audit takes 4–8 weeks from site visit to final report. If your Tier 1 buildings haven’t been audited yet, the window to complete that work, implement improvements, and file before December 2026 is narrowing.
Colorado Building Compliance provides ASHRAE Standard 211 Level 2 audits for commercial and multifamily buildings across the Front Range and statewide. Schedule a consultation to discuss your portfolio, get a scope and fee estimate, and confirm which buildings need audits before the deadline closes in.