What are EER and COP?
EER (Energy Efficiency Ratio) and COP (Coefficient of Performance) are standardized metrics that measure how much cooling or heating output an air conditioning system produces per unit of energy consumed.
EER and COP are the two main ways the air conditioning industry quantifies system efficiency in Australia. EER measures cooling output in BTU per watt of electricity used, while COP expresses the same relationship as a simple ratio, making it the standard metric used on most Perth air conditioning units today. Both numbers tell you how much cooling power you get for each unit of electrical energy consumed.
The higher the EER or COP rating, the less energy your system wastes. A system with an EER of 10 delivers twice the cooling of a system rated EER 5 using the same power. For heat pump systems that provide both cooling and heating, manufacturers list separate COP values for each function, since heating efficiency often differs from cooling efficiency. This distinction matters in Perth's climate where some systems run year-round.
These ratings become practical when comparing running costs and environmental impact across different models and brands. A high-efficiency unit costs more upfront but delivers lower utility bills and reduced carbon footprint over its lifespan. When selecting an air conditioning system or evaluating quotes from contractors, checking the EER or COP rating helps you understand the true operating cost beyond the purchase price. Building standards and rebate programs in Western Australia often reference minimum efficiency thresholds based on these metrics, so contractors typically reference them when recommending equipment for residential and commercial installations.