ASHRAE 90.1

ASHRAE 90.1 is the American Society of Heating, Refrigerating and Air-Conditioning Engineers' Energy Standard for Buildings Except Low-Rise Residential Buildings — the model energy code that sets minimum efficiency requirements for HVAC equipment, lighting, building envelope, and service water heating in commercial buildings. Most U.S. state energy codes adopt ASHRAE 90.1 by reference, often with a few years' lag — for example, a state on 90.1-2019 in 2026 has not yet adopted the 2022 revision.

For chiller specification, the relevant section is Table 6.8.1, which lists minimum full-load (EER, kW/ton) and part-load (IPLV) efficiency by equipment category, refrigerant type, and capacity range. The thresholds tighten with each revision. A 500-ton water-cooled centrifugal chiller that met 90.1-2010 may not meet 90.1-2019, which means a planned replacement in a jurisdiction on the 2019 cycle effectively forces an upgrade to a higher-efficiency unit.

The financing implication: when scoping a replacement, get the current ASHRAE 90.1 cycle adopted by your Authority Having Jurisdiction (AHJ) before you spec the equipment. A lender's underwriting may quote you a payment based on a standard-efficiency unit, but the AHJ may require a higher-efficiency unit at a higher price — adjust the loan amount upward and re-quote. Better to discover the gap during application than at plan review.