NOM-023 test tolerances: how much margin you really have

When the laboratory tests your mini-split, the efficiency it measures almost never matches the one you declared exactly. NOM-023-ENER-2018 accepts a difference of up to 5 %, but with a limit many people overlook: Table 1.

NOM-023 covers split-type air conditioners (mini-split and multi-split), free-discharge and ductless, with a capacity of up to 19 050 W and a single-speed compressor. Inverter units fall under NOM-026-ENER-2015; two-speed units and units designed for ducts are out of scope.

The Table 1 minimum EER

The energy efficiency ratio (EER, «REEE» in the standard) you declare on the label has to be equal to or greater than the Table 1 minimum for your unit's capacity:

The 5 % tolerance

The EER and the capacity the laboratory measures can be up to 5 % below what you declared. But the measured EER can never be below the Table 1 minimum, even if it is within the 5 %.

Your real margin may be smaller

A unit of up to 5 859 W declares an EER of 3.45. The 5 % would let it drop to 3.28, but the Table 1 minimum is 3.37. The real floor is 3.37: its margin is only 2.3 %, not 5 %.

To use the full 5 % in that bracket, the declared EER has to be 3.55 or more.

• Declare with marginThe closer to the minimum, the less real tolerance
• Check the capacityIt can also drop only 5 %
• Confirm the bracketThe capacity decides which minimum applies
• Compare with the marketThe validator shows similar certified units

Frequently asked questions