An ASHRAE energy audit is a commercial building audit performed to one of three levels defined by ASHRAE: Level 1 (walk-through), Level 2 (energy survey and analysis) and Level 3 (detailed analysis of capital projects). The levels build on each other, and the one you need depends on your goals and on any city energy audit requirement that applies to your building. This guide explains what each level includes, how they compare, and which level cities usually require.
ASHRAE, the professional society for heating, ventilation and air-conditioning engineers, publishes the most widely used framework for commercial energy audits. Its Standard 211, Standard for Commercial Building Energy Audits (2018, reaffirmed in 2023), sets minimum requirements for each audit level so that owners, cities and utilities can compare reports.
Standard 211 starts with a Preliminary Energy-Use Analysis (PEA): a desk review of 12 months or more of utility bills that calculates the building’s energy use intensity (EUI) and compares it with similar buildings, often using ENERGY STAR Portfolio Manager. The three audit levels build from there.
A Level 1 audit adds a site visit to the preliminary analysis. The auditor walks the building, talks with operating staff and looks for obvious waste.
A Level 2 audit is the level most energy audit laws require. It goes system by system and puts numbers on every recommended measure.
A Level 3 audit, often called an investment-grade audit, focuses on major capital projects that need a high level of confidence before an owner commits funds.
| Level | Depth | Most often used for |
|---|---|---|
| Level 1Walk-through | Site walk-through and utility analysis; low-cost and no-cost measures | Screening and quick wins |
| Level 2Energy survey and analysis | System-by-system survey with savings and cost estimates for each measure | City audit ordinances and capital planning |
| Level 3Detailed analysis | Investment-grade engineering, metering and modeling of capital projects | Major retrofits and project financing |
Most city and state rules that require an audit ask for ASHRAE Level 2, often by name:
Some programs accept a lighter review: Orlando’s low scorers can complete an ASHRAE Level 1 audit or retro-commissioning. For the full list of cities, frequencies and deadlines, see our energy audit compliance guide.
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A Level 1 audit is a walk-through that identifies low-cost and no-cost measures. A Level 2 audit surveys each system in detail and estimates savings, cost and payback for every recommended measure.
It is the Standard for Commercial Building Energy Audits, published in 2018 and reaffirmed in 2023. It sets minimum requirements for the Preliminary Energy-Use Analysis and for Level 1, 2 and 3 audits.
Local Law 87 requires an ASHRAE Level 2 energy audit, together with retro-commissioning, for buildings over 50,000 sq ft.
They are closely related. A Level 3 audit provides the detailed, investment-grade analysis of capital projects that lenders and energy performance contracts usually require.
For a typical commercial building, plan on several weeks from the site visit to the final report, plus time to gather utility data and building documents.
Related guides: energy audit compliance by city, third-party verification of benchmarking data and our full energy benchmarking compliance guide.
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