What it is about
Part 4‑7 establishes the CER as an indicator for the cooling infrastructure, describes measurement, calculation, and reporting, and explains how to read the value. It is aimed at data center managers, operations managers, ICT managers, and general contractors.
The CER assesses cooling as a subsystem within the data center boundaries; the standard does not set a limit or target value, and individual indicators are not combined into an overall score (EN 50600‑4‑7:2020, Introduction, Clauses 1 and 4).
Core requirements in our own words
The CER is an annual value in kilowatt-hours per kilowatt-hour.
The numerator is the total quantity of heat removed, the denominator the energy consumption of the cooling systems, both for the same twelve months. The standard leaves the measurement frequency open; it only determines when the next rolling annual value is available. Clauses 5.1 and 6.1.
The heat is measured in the cooling medium, not taken as the cooling capacity from the data sheet.
Volume and heat capacity of the coolant must be recorded; with direct free cooling, humidity as well. Redundant pipes are measured individually. Clause 6.2.
The denominator includes the entire cooling chain.
Pumps, valves, and all other components of the cooling infrastructure count; energy is measured in kilowatt-hours, not power in kilowatts. Clause 6.2.
A report states the data center with its system boundary, the value, and the end date.
Externally, the CER is only communicated together with the cooling conditions, such as direct free cooling or water use; for these conditions, the associated indicators should be reported as well. Clauses 7.1 and 7.2.
Shorter periods are called iCER, snapshot values CPR.
The interim CER carries the measurement period in its name; the cooling performance ratio (CPR) relates heat load and electrical power at the same point in time and is used for capacity management. Annex D.1 and D.2.
The reciprocal, CEF, shows the effort per subsystem.
Expressed as a percentage of the heat removed, the cooling efficiency factor can be applied individually to computer room air conditioning units, chiller, and dry cooler and shows which link in the chain consumes the electricity. Annex D.3.
From our seminars: two misconceptions
“The CER is the COP of our chiller.”
The coefficient of performance (COP) describes a machine under fixed test conditions, the CER the entire cooling infrastructure over one year under real outdoor temperatures and part loads. From seminar practice: the comparison helps as an introduction, but the annual value follows the share of free cooling, not the catalog value of the machine (Annex A.2, D.2).
“The nameplates of the cooling equipment are enough to size the power supply.”
The peak load of the cooling depends on IT load and outdoor air temperature, and manufacturer data deviate in real operation. In projects, we often see that the minimum of the CPR shows the actual peak demand better than the sum of the nameplates (Annex D.2.3.2, D.2.4).
Where Part 4‑7 applies in a project
Planning
Site and temperature concept determine the hours of free cooling and thus the annual CER; higher coolant temperatures extend free cooling operation, from seminar practice roughly by two weeks per kelvin (Annex C.1).
Law
The EnEfG requires operators to submit information for the energy efficiency register annually by 31 March, including the efficiency of the cooling system according to DIN EN 50600‑4‑7 (Section 13(1), Annex 3).
Operation
The iCER, plotted against the outdoor temperature, makes the effect of an optimization visible; meters with remote reading and data history are the prerequisite (Clauses 6.3 and 7.3).
This protects you from a cooling system that is efficient on paper and delivers a different value in the register (Clause 6.2).
Status and revision
- Current edition
DIN EN 50600‑4‑7:2020‑11, German edition of EN 50600‑4‑7:2020, approved by CENELEC on 10 February 2020.
- International
ISO/IEC 30134‑7; the correspondence is stated in the national annexes of the German editions of Parts 4‑8 and 4‑9, not in a legal source.
- Revision
No ongoing revision known. Committee CLC/TC 215, nationally DKE/GK 719.
- Last reviewed
EN 50600‑4‑7
Frequently asked questions
The ratio of the heat removed from the data center per year to the annual electricity consumption of the cooling systems, both in kilowatt-hours (Clause 5.1).
No. The partial PUE always lies between 1 and the PUE of the data center and responds little to improvements; the CER directly measures the heat removed per kilowatt-hour used (Annex A.1).
Operators of data centers within the meaning of the EnEfG report the efficiency of the cooling system according to DIN EN 50600‑4‑7 annually to the energy efficiency register; the act covers data centers with a non-redundant rated connected load of 300 kW or more (Sections 3 and 13(1), Annex 3, as of 13 November 2023).
Energy needed to transport heat across the data center boundary counts in the denominator of the CER; distribution in the building beyond it does not. The reuse itself is assessed by the ERF under Part 4‑6 (Annex B.2).
Yes, approximately. With a shared cooling infrastructure, the CER can be used to calculate the cooling share per room; the standard names the uncertainties of this method (Clause 5.2, Annex B.1).
Seminars
Related seminars
- DC-21008
Data Center Sustainability & Efficiency
5 days · In person
All indicators of the 4-x series with formulas, system boundaries, and a comparison with the EnEfG; this saves you a register entry with the wrong reference value.
Next date: 7–11 Jun 2027, Munich · GermanPrice plus VAT: €6,990 Training path 4/4
DC-21004Deep Dive – Power Supply & Cooling
according to EN 50600
5 days · In person · Live webinar
Thermodynamics, free cooling, and adiabatic cooling over the course of the year, that is, the variables that determine the CER.
Next date: 23–27 Nov 2026, onlinePrice plus VAT: €6,990
All prices plus VAT; the price is the same in every format.
- DIN EN 50600‑4‑7:2020‑11 (German edition of EN 50600‑4‑7:2020), Introduction, Clauses 1, 3.1, 4, 5.1, 5.2, 6.1 to 6.3, 7.1 to 7.3, Annexes A, B, C, D
- DIN EN 50600‑4‑8:2023‑08 and DIN EN 50600‑4‑9:2023‑08, national Annex NC of the German edition (relationship with ISO/IEC 30134)
- ISO/IEC 30134‑7
- German Energy Efficiency Act (Gesetz zur Steigerung der Energieeffizienz in Deutschland, EnEfG) of 13 November 2023, Section 13, Section 20, Annex 3
- DCE academy seminar practice: Data Center Sustainability & Efficiency (session November 2025), Data Center – General Principles (session April 2026), Deep Dive – Power Supply & Cooling (session November 2023)
Glossary terms
- Cooling Efficiency Ratio (CER)
- Cooling Performance Ratio (CPR)
- Cooling Efficiency Factor (CEF)
- interim CER (iCER)
- coefficient of performance (COP)
- free cooling
- cooling infrastructure
- German energy efficiency register for data centers (Energieeffizienzregister)
