# Relation between EER,SEER and COP : online converter

## Efficiency of cooling and heating systems :

When buying an air conditioner, look for a model with a high efficiency. Central air conditioners are rated according to their COP, SEER, and EER. The higher the ratio is, the more efficient is the system. They are used as the basis for determining the star rating of an air conditioner.

### What is COP : definition and formula

COP = Coefficient of Performance, ratio used to evaluate efficiency of heating or cooling systems.
COP = Output heating or cooling in Wh / input electrical energy in Wh
Note that for cooling system it is better to use EER coefficient. The relation between EER and COP is :
EER = COP * 3.41

### What is EER : definition and formula

EER = Energy Efficiency Ratio, ratio used to evaluate efficiency of cooling systems.
EER = Output cooling in BTUh / input electrical energy in Wh
EER = 1.12 * SEER - 0.02 * SEER2

### What is SEER : definition and formula

SEER = Seasonal Energy Efficiency Ratio, this ratio is also used to indicates the relative amount of energy needed to provide a specific cooling output. It is expressed in BTU/Whr
SEER represents the expected overall performance for a typical year's weather in a given location. It is calculated with the same indoor temperature, but over a range of outside temperatures from 65 °F (18 °C) to 104 °F (40 °C), with a certain specified percentage of time in each of 8 bins spanning 5 °F (2.8 °C). There is no allowance for different climates in this rating, which is intended to give an indication of how the EER is affected by a range of outside temperatures over the course of a cooling season.

SEER = (1.12-√(1.2544-0.08*EER)) / 0.04

In europe : before 2013 air conditionner and heating systems were rated according to EER and COP. These ratio were calculated for only one measurement at full charge.
Since 2013 the ErP directive set SEER and SCOP. They are calculated for 4 measurement In US : http://www.fsec.ucf.edu/en/publications/html/FSEC-PF-413-04/ For Heat Pump : http://energy.gov/energysaver/air-source-heat-pumps https://www.energystar.gov/products/heating_cooling/heat_pumps_air_source/key_product_criteria http://www.nrcan.gc.ca/energy/publications/efficiency/heating-heat-pump/6831