ASHRAE Standard 211 defines three levels of commercial energy audit. Level I is a quick screening. The real choice for most owners is between Level II and Level III. Picking the wrong one either wastes money or leaves you without numbers you can act on.

Level II: energy survey and analysis

A Level II audit surveys every major energy-using system, breaks down energy use by end use, and calculates savings and costs for each recommended measure. It is the standard audit for capital planning and the level required by NYC Local Law 87.

  • Accuracy: savings estimates typically within ±20–30%.
  • Timeline: about 4 to 8 weeks.
  • Best for: LL87 compliance, building-wide capital plans, utility incentive applications, LL97 strategy.

Level III: investment-grade audit

A Level III audit takes selected capital-intensive measures from a Level II study and engineers them in detail. It adds data logging, trend analysis, a calibrated energy model and contractor-grade cost estimates.

  • Accuracy: savings estimates typically within ±10–15%.
  • Timeline: about 2 to 4 months.
  • Best for: energy performance contracts, NJ ESIP projects, projects that need lender or board approval, deep retrofits and electrification.
A simple rule: if someone is going to finance the project against the predicted savings, you need Level III. If you are deciding what to do and in what order, Level II is enough.

Can you do both?

Yes, and that is common. A Level II audit identifies the full list of opportunities. A Level III study then focuses only on the two or three large measures worth financing, so you don't pay for investment-grade detail on a lighting retrofit.

Compare all three levels on our energy audits page, or ask an engineer which level fits your building.