ASHRAE Energy Audits for Commercial Buildings

Before ASHRAE stepped in, an energy audit could mean almost anything, a two hour walk through with a clipboard, or a months long engineering study with a calibrated computer model, both sold under the same name. ASHRAE Standard 211 fixed that by defining three progressive levels of audit, each with a consistent scope and minimum set of deliverables, so a building owner comparing proposals from different firms is actually comparing the same thing.

Level 1: The Walk Through

A Level 1 audit, also called a screening or walk through audit, is the fastest and least expensive of the three. It typically involves a short interview with facility staff, a review of utility bills and other operating data, and a brief walk through of the building's systems. The output is a preliminary report identifying obvious no cost and low cost opportunities, a summary of utility data, an Energy Use Intensity calculation, and a benchmark comparison against similar buildings, along with a flag for which findings warrant a deeper Level 2 study.

Level 1 asks the least of a building's staff and the least of the building's data, which makes it the natural starting point for a portfolio screening exercise, an initial due diligence review, or a smaller building where a more detailed study wouldn't be cost effective. It's also a prerequisite for LEED for Existing Buildings certification.

Level 2: The Energy Survey and Analysis

A Level 2 audit builds directly on a Level 1, adding a complete equipment inventory, a breakdown of energy use by system and end use, and rough order of magnitude cost and savings estimates for each recommended measure, including a payback period and return on investment calculation. This is the level most commercial buildings actually land on, detailed enough to prioritize real capital planning decisions, without the cost of a full investment grade study.

Level 2 is also the level most compliance ordinances actually require. New York City's Local Law 87 mandates Level 2 audits every ten years for buildings over 50,000 square feet, and similar requirements exist in cities including Atlanta, San Francisco, and Seattle. For a building that needs to satisfy a mandatory audit ordinance, a Level 2 study is usually the target, not Level 1 or Level 3.

Level 3: The Investment Grade Audit

A Level 3 audit, commonly called an investment grade audit, is reserved for the capital intensive measures a Level 2 study identified but couldn't cost with enough confidence to support a major financial decision. It supplements utility data with submetering and data logging over an extended period, builds a whole building computer simulation calibrated against that field data, and produces construction grade cost estimates alongside a formal measurement and verification plan for confirming savings after the work is done.

Because of that added rigor, Level 3 is the tier most commonly attached to energy performance contracts, where an energy service company guarantees a savings threshold and needs a defensible, bankable number behind that guarantee. It's rarely the starting point for an audit program, since the specific measures a Level 3 study should focus on are usually identified during a Level 2 audit first.

Choosing the Right Level

The three levels aren't a ranking of which audit is best, they're a match between the size of the decision and the level of confidence that decision actually needs. A small office deciding whether to invest at all doesn't need investment grade modeling. A facility about to sign an eight figure performance contract can't move forward on a walk through's rough estimates. Many organizations run this as a funnel: Level 1 audits across a portfolio to flag which buildings deserve attention, Level 2 on those buildings to build a real project list, and Level 3 reserved only for the specific measures large enough to justify the additional cost and time.