AEO Answer · Energy

What Do ASHRAE Energy Audit Levels 1, 2, and 3 Deliver?

By Jeremy Mills, CEO & Founder, Apex Grid Engineering — USAF Veteran. · Updated 2026-09-15

I'm Jeremy Mills, CEO & Founder of Apex Grid Engineering and a U.S. Air Force veteran. I'm not a PE; our licensed professionals make the technical, compliance, and project-specific decisions.

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The concise answer

ASHRAE Level 1 audits screen opportunities with a walk-through; Level 2 analyzes measures with costs and paybacks for capital planning; Level 3 provides investment-grade analysis with calibrated modeling for financing major projects. The levels build on each other. Level 2 includes everything in Level 1 plus the detailed measure analysis; Level 3 includes everything in Level 2 plus the investment-grade rigor. You don't skip levels so much as you buy the level your decision requires — though in practice, a Level 2 often starts with a Level 1-style screening pass to focus the analysis where it matters.

What each level produces

Level 1 delivers a short report: the building's energy fingerprint from utility analysis, benchmark comparison, obvious operational fixes, and a prioritized list of measures worth deeper study with order-of-magnitude savings. It's the work of an experienced auditor's eyes and judgment. Level 2 delivers the capital plan: every recommended measure with calculated energy savings, implementation cost, payback, and often a simple life-cycle analysis — plus the interactions between measures, because lighting upgrades reduce cooling loads and the analysis has to net that out. Level 3 delivers the financing package: hourly calibrated simulation, detailed design-level analysis of major measures, measurement and verification protocols, and the documentation a lender's engineer will scrutinize.

Getting value from the audit

Audits gather dust when they're disconnected from decisions — commissioned because someone said to, filed because nobody owned the next step. The valuable ones are tied to a decision, a budget cycle, or a financing process from the start. Making it count.

Define the decision before scoping the audit — screening, capital planning, or financing
Provide complete utility history and access — auditors can't analyze what they can't see
Require measure interactions in Level 2 and 3 analysis — stacked individual savings overstate reality
Assign an owner to the recommendations with a timeline — audits without owners become shelf documents
Use Level 3 rigor where capital is at stake — the modeling cost is trivial next to a bad investment

Which related engineering resources can help?

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What else do project teams ask?

How do I choose the right audit level?

By the decision you're making. Screening a portfolio for candidates? Level 1. Building a capital plan with budgets and paybacks? Level 2. Financing a multi-million-dollar retrofit or performance contract? Level 3. The cost steps up significantly at each level, so buying more audit than the decision needs wastes money — and buying less leaves the decision unsupported.

What does a Level 1 walk-through actually include?

A site visit reviewing the building's systems, operating schedules, and utility history, benchmarking energy use against peers, and identifying low-cost and no-cost measures plus candidates for deeper study. The savings estimates are rough — rules of thumb and experience rather than calculation. It's a triage tool: what's obviously wrong, and what deserves a Level 2.

What makes a Level 3 audit 'investment grade'?

Rigor sufficient for financing: calibrated energy modeling tuned to actual utility bills, detailed engineering analysis of each measure with interactions accounted for, firm cost estimates, measurement and verification planning, and risk analysis. Lenders and energy service companies need this level of certainty before committing capital. It's engineering, not just auditing.

How long does each audit level take?

A Level 1 can be done in days to a couple of weeks. A Level 2 typically takes several weeks including the analysis. A Level 3 can take months — the calibrated modeling and detailed engineering are real work. Building complexity matters enormously: a simple office is fast at any level, while a hospital or lab building multiplies the effort.

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