Rising heat and humidity challenge energy-efficient data center cooling

Reliable operation of data centers has become essential to nearly all sectors of modern society, including healthcare, education, government services, power grid operation, banking, defense, and disaster relief. New research published in Scientific Reports and led by University of Hawai‘i (UH) at Mānoa atmospheric scientists revealed that future climate conditions may reduce the availability of one of the cheapest and most energy-efficient approaches to cooling data centers. 

The research team, led by Christina Karamperidou, atmospheric sciences professor in the UH Mānoa School of Ocean and Earth Science and Technology, assessed historical and projected temperatures and humidity levels around the world and compared them to the conditions required for “direct air free cooling”, wherein naturally cold outside air is brought in to cool a building or equipment. 

“We found that periods of time when temperature and humidity exceed recommended operating thresholds for direct air free cooling are becoming more frequent and lasting longer in many regions,” said Karamperidou. “This will reduce the availability of air free cooling for a growing number of data centers globally.”

Looking to the past and future

Karamperidou and co-authors combined high-resolution hourly weather observations with climate model simulations and a global database of data center locations. This allowed them to evaluate how often environmental conditions exceeded recommended operating limits for direct air free cooling, both historically and in future climate scenarios. By analyzing global datasets, they were able to identify large-scale patterns and trends that would not be visible from studies focused on individual facilities.

The researchers found over the past 45 years, the number of hours characterized by high temperature and humidity conditions that limit direct air cooling has increased significantly, particularly across the tropics and the southeastern United States. A site- and market-level analysis further showed that the share of data centers exposed to conditions that limit air free cooling availability for at least one quarter of the year is rising. Projections through mid-century indicate continued expansion of these constraints with sustained warming and increasing humidity. 

One of their key findings is that the largest changes are not always seen in average conditions. In several regions, worst-day conditions are intensifying more rapidly than average conditions, indicating that environmental stress is becoming increasingly concentrated in rare but consequential events.

“From an operational perspective, those worst-day conditions often drive contingency planning, system overrides, redundancy requirements, and reliability decisions,” Karamperidou shared.  “This suggests that infrastructure planning may need to account not only for average environmental conditions but also for how the most stressful days are changing over time.” 

Climate, computing, energy and water issues converge

A confluence of factors presents a substantial societal challenge: with the artificial intelligence boom, the demand for data centers is increasing, just as climate conditions are limiting an efficient approach to cooling these facilities. Understanding this change is critical for long-term resilience and sustainability. 

“Our study examined a question that sits at the intersection of climate, computing, energy, and water resources,” said Karamperidou. “We hope this work helps identify where emerging technologies and new cooling approaches may help address trade-offs among reliability, energy consumption, and water use.”

This work was developed in collaboration with researchers working on cyberinfrastructure and next-generation cooling technologies, including partners through the NSF ERC EARTH, where UH is a key partner institution.