# Cooling Efficiency Ratio (CER)

Cooling Efficiency Ratio (CER) is a measurement paramenter used to assess the efficiency of the cooling system in removing heat in a data center. The parameter calculates the ratio between the amount of heat removed and the energy consumption of the cooling system.

CER is part of the EN 50600 standard.

### How is the Cooling Efficiency Ratio (CER) calculated?

CER is calculated by dividing the total amount of cooling efficiency (in kilowatts) the cooling system provides by the total amount of electrical energy that the cooling system uses (also measured in kilowatts).

CER is calculated using the following formula:

Example: A data center uses 50 kW/h for cooling. The total kW/h of heat that was removed is 100 kW/h. You then get a ratio of 0.5 kW/h used per 1 kW/h of heat that is removed. In this instance, it means that 50% of the energy in the form of electricity is used to remove the energy in the form of heat.

If you reverse the formula and use the total number of kW/h of heat divided by the number of kWh/ used for cooling, the bigger the pile the better. This is in accordance with EN 50600.

### The meaning of high and low CER

A high CER value implies that the cooling system removes heat efficiently from the data center with low power consumption. On the other hand, a low CER value uses a lot of electrical energy in the cooling system to remove heat, which leads to increased costs and reduced energy efficiency.