BTU, Kilowatts or Horsepower?

BTU, Kilowatts or Horsepower?

The Background
In Australia, it is known that manufacturers can express the output of their products in one of 3 different electrical measurements: Kilowatts, BTU's or Horsepower. This represents a problem for anyone researching air conditioning for the first time, as it is difficult to compare products when the electrical capacity is advertised in different ways.

Kilowatts:
In Australia, the metric system is used, so the correct expression of output of a split system air conditioner is Kilowatts.

BTU:
A British Thermal Unit (BTU) is the amount of energy (heat) required to raise the temperature of one pound of water by one degree Fahrenheit. (1 BTU = 1 lb. x 1°F).

As the US still use imperial measurements (such as feet, inches, yards and Fahrenheit) - you will find that some air conditioners slip into Australia with their American promotional material advertising their output in BTU.

It is the authors opinion that the distributors of products who express their output in BTU should be avoided, as it is clear that the distributor:

1. Isn't aware Australia changed to the metric system in 1970 (!)
2. OR: Hasn't bothered to update the promotional material before going to market (If this is the extent of their pre-sale preparation, imagine what their after sales service is like?! It will be ordinary). Best to avoid.

Horsepower:
Horsepower rating is actually the rated capacity of a motor. This is ambiguous as the figure does not translate to the Energy efficiency rating (EER) or co-efficiencies of performance (COP) that can be achieved through refrigerated air conditioning.

For example: A 2.5hp motor in one brand might have an output of 5.4kW, whereas another brand with a 2.5hp motor might give you an output of 6.4kW. (A difference of 1kW!). With one brand having the ability to have a higher EER over another, (but the same capacity motor) horsepower is an unreliable measurement to compare air conditioners.

How to calculate EER and COP

Please take a look at this page to understand how Energy Efficiency Ratings (EER) and Co-efficiencies of Performance (COP) can be calculated and compared.

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