Whitepaper: IEER vs ISMRE

Commercial Ducted Systems Efficiency Rating Metrics 

IEER - Commercial Rooftop Units

The majority of commercial unit efficiencies are based upon ASHRAE Standard 90.1 minimum values (table 6.8.1) and AHRI-340/360 standard testing conditions. The intent of the standards is to provide an efficiency measurement for package and split systems air conditioning equipment used for space temperature conditioning applications.

ISMRE270 Dedicated Outside Air Systems

The industry created a new DOAS efficiency standard, AHIR 920, that better represents the product application which is dehumidification. ASHRAE 90.1 has adopted the standard and provides a minimum efficiency for the units.