Cooling is often one of the largest non-IT energy uses in a data center. Measuring cooling performance separately from total facility efficiency helps operators identify where cooling energy is being consumed and where improvements are possible.
Use the CER KPI
ISO/IEC 30134-7:2023 specifies Cooling Efficiency Ratio (CER) as a KPI for quantifying efficient use of energy to control data-center environmental conditions.
Define included cooling energy
Measurement should consistently account for the cooling components within the selected boundary, such as chillers, pumps, heat-rejection equipment and air-moving systems where applicable.
Correlate with load and ambient conditions
Cooling efficiency changes with IT load, outdoor conditions, supply temperatures, flow rates and equipment staging. Trend analysis should therefore include operating context.
Optimize control sequences
Improvement opportunities can include chilled-water temperature optimization, variable-speed control, equipment sequencing, airflow management, containment and reducing unnecessary bypass or recirculation.
Do not sacrifice thermal compliance
Energy reduction is only useful when IT inlet conditions and equipment requirements remain within the approved operating envelope. Efficiency changes should be validated by monitoring and testing.
References
- ISO/IEC 30134-7:2023, Cooling efficiency ratio (CER).
- ISO/IEC 30134-1:2016, Overview and general requirements.
