Record Heat Puts Data Centers under Pressure

Stuttgart, Germany, August 31, 2026. Digital infrastructure is facing severe strain from record heat. Cooling requirements of data centers – the backbone of cloud services, payment transactions and communication – increase significantly during hot weather. “For a long time, heat was an issue of secondary importance for data centers. Now, many of them are becoming heat traps: outdoor temperatures are rising, while the heat inside is increasing as a result of artificial intelligence (AI) applications and higher-capacity chips. If cooling capacities are not adjusted in time, there is a risk of failures and possibly expensive outages. At the same time, digital infrastructure is becoming increasingly vulnerable to extreme weather,” commented Mathias Franke, head of data center consulting at the advisory firm Drees & Sommer SE.

The tech boom is increasingly posing challenges: in Germany, data center capacity has more than doubled since 2010, and reached more than 2,730 megawatts in 2024. The Federal Ministry for Economic Affairs and Energy (BMWE) expects a further growth acceleration to 4,800 MW by 2030. This corresponds to a plus of around 75 percent within just six years.[i] In March 2026, the Federal Government adopted the first national data center strategy[ii] with the goal of at least doubling Germany’s data center capacity by 2030. 

Growth is predominantly driven by cloud and artificial intelligence (AI) applications. At the same time, digital infrastructure is becoming increasingly vulnerable to extreme weather. An analysis by First Street, published in June 2026, reveals that 54 percent of global data center capacity operates in markets facing elevated chronic heat or drought stress. The company specializes in specializes in climate risk financial modeling. [iii] 

Data Heat Island Effect: Data Centers Push Up Temperatures in the Immediate Vicinity

Mathias Franke explained: “AI is fundamentally changing the demands on data centers. The facilities are not only consuming more energy, but are also discharging more heat into their surroundings. Operators will have to give greater consideration to this problem when designing and operating data centers in the future. According to a study, conducted together with the University of Cambridge and published in March 2026, the land surface temperature (LST) increases by two degrees Celsius on average in the vicinity of AI data centers. In extreme cases, the temperature can rise by up to 9.1 degrees Celsius. Hence, more than 340 million people could be affected by the impact of the data heat island effect worldwide.[i]

Outages due to heat are not unavoidable. Risks can be significantly reduced by adapting cooling systems, energy supply and operations to extreme weather events at an early stage. Drees & Sommer’s experts say that operators have to plan ahead in terms of location and technology, and clear measures have to be defined for data center operations during extreme heatwaves.

Knowing Cooling Limits and Reserves before the Heat Event

Cooling systems are pushed to their limits more quickly during spells of extreme heat than had previously been assumed. Researchers of Google and the University of Pennsylvania show in their study entitled ‘Prometheus’ that data centers are required to upgrade their cooling capacity by eleven percent on average to maintain the current outage risk level. At the most challenged sites, cooling capacity could need to be increased by up to 48 percent. For this study, the research team analyzed historical climate data and combined these observations with forward climate simulations for the sites studied. “Operators need to investigate what outside temperatures their cooling systems tolerate and what impact several days of heat will have on their reserves,” Mathias Franke pointed out.[i]

Forward planning is of utmost importance in the design of the cooling system. Franke suggests that operators should use forecast simulations, such as the ‘Extreme Annual Design Conditions’ of ASHRAE Meteo[ii], to enable this. Based on the data from 2025, the recommendation is to plan for the extreme temperatures expected over the next twenty years, adding a temperature increment of four kelvin for safety. The expert said: “Heatwaves are becoming more extreme, last longer and are occurring more often. Future forecasts could therefore be based on even higher temperatures.”

To face extreme heat challenges, operators not only have to upgrade their IT systems. The emergency power system must also function reliably in high temperatures. If its cooling system fails, it can no longer be relied on to supply the data center with electricity. In this case the entire plant is at risk.

Preparing Operations for Heatwaves 

Not every computationally intensive task has to be done when temperatures are at their highest. Backups, data analyses and major data migrations can be postponed until the temperature falls at night. This relieves the burden on the cooling system when its reserves are particularly low. If a cooling system fails, a second one has to take over without delay. The emergency power system has to safeguard the cooling system in addition to the servers. Otherwise, it will often only postpone the outage by a few minutes. Where there are interruptions in the public supply, local micro electricity grids with own energy sources and storage capacities can also continue to supply critical facilities.

Cooling with Water instead of Air

Where individual server racks are using around 50 kilowatts of electricity or more, no air cooling system is likely to be sufficient. Many data centers were originally designed for significantly lower power densities. For a long time, server racks were operated on five to ten kilowatts of electricity, but AI applications are currently pushing up the demand significantly. ”Water can absorb and remove considerably more heat than air. The cooling capacity of water is much higher. For this reason, more and more of our clients are choosing water-based cooling systems where power densities are high,” commented Drees & Sommer’s data center expert. This applies in particular to artificial intelligence and other high-performance applications. 

For moderate power densities, air cooling remains as a more simple and cost-effective solution. Hybrid systems allow only particularly high-capacity areas to be converted to liquid cooling initially. This enables these areas to be cooled reliably even where outdoor temperatures are high. 

Higher Efficiency Is a Must

The German Energy Efficiency Act (EnEfG) provides for higher requirements on new data centers starting operations on or after July 1, 2026. Benchmark is the power usage effectiveness. PUE is the total power consumption of a data center in relation to the energy required to run the servers and storage devices. In simple terms, a PUE value of 1.2 means that, if power consumption to run the IT equipment is 100 kilowatt-hours, for cooling, electricity supply and other technical infrastructure, the total consumption is at most 20 kilowatt-hours. New data centers are required to have a maximum PUE of 1.2. Facilities that went into operation before July 2026 have to achieve a maximum PUE of 1.3 by July 2030.[i]

Mathias Franke pointed out: “Efficient cooling concepts are no longer only a matter of ensuring operational reliability – they are increasingly also a legal requirement. Businesses still relying solely on air cooling are creating a cooling problem for the next ten years. Water-based systems make it easier to plan ahead, especially if temperatures continue to rise and statutory efficiency requirements become stricter.” At the same time, there is currently much discussion regarding an amendment to the German Energy Efficiency Act (EnEfG). If it comes into effect in the coming months, thresholds and limits could be adjusted.[ii]

When Cooling Water Becomes Scarce

Plans for data centers have to allow for future hot spells right from the start, in the choice of a location and in their cooling concept. This applies particularly to water-based cooling systems: in regions where water resources are becoming scarcer, cooling systems themselves can pose a risk. Closed cooling systems reduce water consumption, which eases this problem. The cooling agent circulates continuously between the servers and the cooling system instead of being lost through evaporation (as in adiabatic cooling). After the first fill, they need hardly any additional water during the cooling cycle. It is not so much the large, professionally operated plants with redundant cooling and emergency power that are particularly at risk during hot spells, but the many server rooms within individual companies, often in repurposed basement or plant rooms without appropriate air conditioning systems.

Outages Are No Longer a Future Scenario

The heatwave in the United Kingdom in the summer of 2022 demonstrated how quickly high temperatures can knock out data centers. As temperatures in London passed the 40-degree mark for the first time ever, several cooling systems in the Google Cloud data center failed at the same time. Engineers had to shut down parts of the servers to avoid technical damage. An Oracle data center in the south of London was also affected: the cooling units were working at maximum capacity and ultimately failed. The outage lasted around 19 hours and impacted cloud services worldwide. According to the German Datacenter Association, there were no wide-scale outages during the record high temperatures in Germany in June this year. However, the association has not ruled out shutdowns as a last resort if technical incidents and power shortages occur simultaneously [i].