What Does the Term Horsepower Mean?

29 June, 2022

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Q: What does the term horsepower mean in terms of an air conditioner capacity?

A: The ongoing use of horsepower by retailers is of concern to energy regulators in Australia. This term bears no relation to the output capacity of the unit. The only valid capacity measure is the kW output under AS/NZS3823 condition T1 for cooling or H1 for heating. The term horsepower came from a time when airconditioner compressors where driven with mechanical motors. The output of an airconditioner depends on the motor efficiency, the compressor efficiency, the evaporator and condenser design and heat transfer properties, relative size of the evaporator and condenser, air flow design over the evaporator and condenser, fan efficiency and size, control system etc. Defining the input or output power of the electric motor in such a system as a proxy for capacity is completely misleading in all cases.

At Factory Direct Home Air Conditioning we quote the capacity of a unit in kW.  If another retailer quotes you horsepower, please ask them to give you the capacity in kW so that you can make an accurate comparison.

A unit with poor efficiency may have an output of 2.0kW but is marketed at 1 Horsepower and a unit with a high efficiency with an output of 2.7kW may also be marketed at 1 Horsepower, so it is difficult to compare based on horsepower but easy to compare based on kilowatts.