An ordinary energy-efficient commercial building property analysis creates two digital versions of the same building. One represents proposed or as-installed systems; the other follows the applicable American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) reference rules.
Qualified software calculates covered annual energy and power costs under a consistent comparison. Utility bills can provide context, but they do not replace this statutory modeling test.
Two models
Hold comparison assumptions consistent
Geometry, occupancy, schedules, climate, and other prescribed assumptions must follow the applicable method. System inputs change where the rules require the proposed and reference buildings to differ.
The model is not a free-form forecast. Preserve the software name and version, input files, output reports, and reviewer decisions.
Illustrative covered annual costs
HVAC/hot water and lighting combine into the modeled totals.
$150,000 HVAC/hot water + $50,000 lighting
$110,000 HVAC/hot water + $30,000 lighting
| Item | Value | Note |
|---|---|---|
| Reference building | $200,000 | $150,000 HVAC/hot water + $50,000 lighting |
| Proposed building | $140,000 | $110,000 HVAC/hot water + $30,000 lighting |
Reference edition
Choose the federal baseline from project dates
Announcement 2024-24 identifies ASHRAE 90.1-2007 for 2015-2026 service dates, 90.1-2019 for 2027-2028, and 90.1-2022 after 2028, with a rule allowing 90.1-2007 for property whose construction began before 2023.
Local code compliance and the federal tax baseline are related engineering contexts but not automatic substitutes.
Covered costs
Convert modeled energy into the defined annual-cost comparison
Assume reference HVAC/hot water costs of $150,000 and lighting costs of $50,000, totaling $200,000. Proposed costs of $110,000 and $30,000 total $140,000. The illustrative reduction is ($200,000 − $140,000) ÷ $200,000 = 30%.
At 30% for a tax year beginning in 2026, preliminary rates are $0.69 base or $3.57 increased. Those rates remain subject to every path and amount requirement.
Input-to-certification path
Installed facts can require a model update before certification.
Plans
Systems and schedules
Qualified software
Reference comparison
Field inspection
Observe installation
Signed evidence
Reconcile and certify
Installed building
Field evidence feeds back into the final model
Substituted equipment, revised controls, changed glazing, and actual operating details can alter model inputs. The ordinary-route field inspection occurs after the property is placed in service and supports reconciliation to installed conditions.
A modeler, designer, and certifier need not be the same person. The applicable guidance requires an unrelated, appropriately licensed engineer or contractor for ordinary-route certification.
Model record
A reviewer should be able to reproduce the comparison logic.
| Review point | Evidence or measure | Why it matters |
|---|---|---|
| Reference selection | Edition + reason | Service and construction dates support the choice. |
| Software | Name + version | Confirm the version on the DOE list. |
| Installed inputs | Source record | Tie schedules, submittals, and observations to assumptions. |
Prepare the review
Organize model-ready records
- Construction-start and service dates
- Applicable ASHRAE edition
- Qualified software and version
- Geometry and area source
- HVAC/hot-water inputs
- Lighting and controls inputs
- Envelope assemblies
- Schedules and operating assumptions
- Field changes and inspection support
- Signed certification and tax limits
Common questions
Practical answers before the review
Is the reference building the old building?
No. It is a prescribed comparison model under the applicable federal method.
Can utility bills replace the ordinary model?
No. Existing utility bills alone do not establish the ordinary reference-building test.
Why does software version matter?
The analysis must use qualified software and an applicable version and method.