CASE46 · Data centers · PUE diagnosis and cooling improvements
Tracing a floor-level PUE anomaly to fan operation and staged cooling improvements
A multi-center program links weekly analysis and operator action to PUE, cooling states and measurement quality. Pilot EC-fan results, rollout estimates and ongoing tower tests remain separate.
01 · CASE ANALYSIS
PUE starts the investigation
On 16 August 2017 at 13:00, a room/floor PUE of 1.848 exceeded the center average of 1.576. Inspection found cooling units operating fans without active cooling.
The observed gap of 0.272 is not itself a savings claim; it identifies the equipment states that require operational review.
02 · CASE ANALYSIS
Weekly analysis and measurement quality
After June metering/data integration and UPOS construction, weekly Monday–Sunday operating records were analyzed, discussed in task-force meetings and converted into center-specific actions.
Only one center had adequate measurement consistency at the time; several others were still undergoing validation/calibration. Cross-center benchmarking waited for comparable data.
| Time | Room/floor PUE | Center PUE | Observed gap |
|---|---|---|---|
| 16 August 2017, 13:00 | 1.848 | 1.576 | 0.272 |
03 · CASE ANALYSIS
Pilot fan replacement and scaling
Two centers piloted EC-fan replacement and reported 63.5% lower fan power from before/after comparison: saving = (Pbefore − Pafter) / Pbefore × 100.
A later expansion estimate covered approximately 400 cooling units, with 55% fan-power reduction, KRW 1.1 billion/year benefit and approximately two-year payback. Individual pilot kW values are not available in the public source.
04 · CASE ANALYSIS
Free cooling and tower-test status
Free-cooling expansion was evaluated at KRW 426 million/year potential, KRW 1.757 billion investment and approximately 4.13-year simple payback.
Cooling-tower seasonal setpoint tests were still in progress at the intermediate-report date. No completed temperature-change or tower-energy result is invented.
| Measure | Reported quantity | Evidence status |
|---|---|---|
| EC-fan pilot | 63.5% fan-power reduction | Two-center pilot result |
| Approximately 400-unit expansion | 55%; KRW 1.1 billion/year; KRW 2.2 billion investment | Estimated rollout |
| Free-cooling expansion | KRW 426 million/year; 4.13-year payback | Investment-study potential |
| Tower seasonal settings | Tests in progress | No completed saving quantified |
05 · CASE ANALYSIS
Continuous improvement lesson
Move from PUE anomaly to cooling/system diagnosis, equipment cause, small-scale tests, economics and M&V. Balance tower fan electricity against downstream cooling effects.
The broader program also reviewed pumps, chiller/cooling-unit COP, service temperatures and support loads. CASE38 presents a related program overview; its figures should not be added again.
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