Net energy impact of raising server inlet temperatures beyond 27 °C

Determine whether increasing server inlet temperatures beyond 27 °C yields additional overall energy benefits for entire data centers by reducing cooling infrastructure energy more than the associated increase in server-fan energy, ideally via controlled experiments.

Background

The report investigates the trade-off between data center cooling infrastructure energy savings from higher server inlet temperatures and the concomitant rise in server-fan energy consumption. Using primary data from two colocation data centers, the authors confirmed a positive correlation between inlet temperature and server power on room level (approximately 0.35–0.5% per °C in the 23–30 °C range), but building-level analyses produced conflicting results.

Because the cumulative building-wide effect was ambiguous—with some temperature changes correlating with higher total energy and others with lower—the authors conclude that it remains unresolved whether pushing inlet temperatures beyond the ASHRAE upper limit of 27 °C delivers net energy benefits. They suggest that controlled experiments would be the most effective way to isolate the temperature effect from confounders such as variable computing loads.