Understanding Air Conditioner Ratings: What Do They Mean?

When considering having a new air conditioning unit installed in Essex, it’s easy to become overwhelmed by the array of ratings and numbers. But understanding these ratings is crucial to making an informed decision. In this blog, we’ll break down the most important air conditioner ratings and what they mean for your comfort and energy efficiency.

Seasonal Energy Efficiency Ratio (SEER)

The SEER rating measures the cooling efficiency of an air conditioner over an entire cooling season. It is calculated by dividing the total cooling output during a typical cooling season by the total electric energy input during the same period. A higher SEER rating indicates a more energy-efficient unit. For example, a unit with a SEER rating of 16 is more efficient than one with a SEER rating of 13. Modern units generally range from 13 to 21 SEER.

Energy Efficiency Ratio (EER)

The EER rating measures the cooling efficiency of an air conditioner at a specific temperature (usually 35°C). This rating provides a snapshot of efficiency under peak conditions, rather than over a season like SEER. Higher EER ratings mean greater efficiency, which is particularly important in hot climates where the air conditioner runs constantly.

British Thermal Units (BTU)

BTU measures the cooling capacity of an air conditioner. It indicates the amount of heat the unit can remove from a room per hour. The higher the BTU rating, the more powerful the air conditioner. However, bigger isn’t always better – a unit that’s too powerful for your space will cycle on and off frequently, leading to inefficiency and uneven cooling.

Annual Fuel Utilisation Efficiency (AFUE)

Though more commonly associated with heating systems, AFUE ratings can also apply to heat pumps that provide both heating and cooling. The AFUE rating indicates how efficiently the unit converts fuel into heat over a heating season. A higher AFUE rating means higher efficiency.

Coefficient of Performance (COP)

COP is a ratio of useful heating or cooling provided to work required. A higher COP means the air conditioner is more efficient. For cooling, a COP above 3 is generally considered good.


Understanding air conditioner ratings is essential for choosing the right unit for your home. Pay attention to SEER and EER for energy efficiency, BTU for capacity, and AFUE and COP for overall performance. Making an informed choice not only ensures comfort but also helps in reducing energy bills and environmental impact.

For more detailed advice on selecting the right air conditioner, get in touch today for honest advice and a free no-obligation quote.