At 41 degrees, nearly all land could run data centers without chillers all year

Why data centers need so much power

Data centers are hungry for electricity because they do two things at once: they run computers that never sleep, and they keep those computers from overheating. The first job is obvious, while the second is less visible but can still add a lot to the bill. In a conventional room set near 22 C, air must be cooled by machines called chillers whenever outside weather cannot provide cold enough air for free. Those chillers draw power even when the servers themselves are not changing.

A global calculation built from worldwide weather records and server performance measurements put a number on that hidden cost. It compared the cooling energy needed in a typical 22 C room with what would be required if the space ran at 41 C. The calculation calls that warmer setting the global free-cooling temperature. At that level, nearly all land area could rely on outside air for cooling throughout the year. Compared with a current typical room at 22 C, it found savings of up to 56 percent in cooling energy.

That does not mean every data center can simply turn off its chillers tomorrow. The proposal is aimed at the cooling side of the bill, where weather, room temperature and equipment design all interact. It points to a reason why power demand keeps climbing: much of it is spent moving heat out of buildings that could sometimes be kept warm enough for nature to do that work.

What happens when server rooms run at 41 degrees

Server rooms are usually kept near 22 degrees, but a hotter room can change the cooling bill. A model built from worldwide weather readings and server performance measurements found that 41 degrees is a useful threshold. At that space temperature, nearly all land areas could use outside air to remove heat all year long. The phrase global free-cooling temperature is used to capture this threshold. It means chillers, machines that pump heat out with refrigeration, could stop being needed in most places. The possible saving is large for many sites compared with a typical 22 degree room. Operating at 41 degrees could cut cooling energy use by up to 56 percent. That figure is an upper bound, not a promise that every site will save exactly that much. It depends on local weather, building design, and how the servers respond to heat. The result matters because cooling is one of the main ways data centers draw power from the grid. If rooms can stay warm enough for outside air to do the work, the need for mechanical refrigeration falls sharply. This does not mean every server room should be set to 41 degrees without care. The same analysis also looks at how servers behave in that heat and sets targets for equipment that can tolerate it. For a reader, the main point is simple: hotter rooms can turn cooling from an energy cost into a seasonal advantage.

The trade-off between cooler air and hotter servers

A global analysis of weather records and server performance found that hotter rooms can cut chiller use sharply. The saving comes from free cooling, which uses outside air instead of mechanical refrigeration. At a typical room temperature of 22 degrees Celsius, many sites still need chillers for part of the year. Raise the space to 41 degrees, the global free-cooling temperature. Nearly all land can then use free cooling year round. In that case, cooling energy could fall by up to 56 percent compared with operation at 22 degrees. That figure is a ceiling, not a promise for every building. The gain depends on climate, equipment age, and how much the servers themselves change their power draw. Warmer rooms were paired with higher server power, so some saved chiller energy returns to the racks. The net benefit appears when cooling demand falls more than server load rises. That balance explains the targets for ideal and recommendable servers, which should keep performance steady in heat. Those machines should not demand much extra electricity as temperatures climb. A cooler room protects components, but it also burns energy to remove heat from a small space. A hotter room shifts the burden toward equipment, yet outside air can do most of the work. The trade-off is therefore about which side saves more power over a year.

A warmer room as a global cooling strategy

The central finding is simple enough to state without any special equipment: if server rooms are allowed to run at 41 degrees Celsius instead of the usual 22 degrees, most land areas on Earth could rely entirely on outside air for cooling all year long. A comparison built from worldwide weather records and server performance data puts a number on that possibility. Cooling energy savings could reach up to 56 percent compared with today’s cooler rooms.

That is an opportunity because the biggest saving comes not from one clever machine but from changing the target temperature itself. Data centers can stop treating heat as waste and start designing around it, using free air when climate allows and reducing dependence on chillers that consume power in their own right. The same logic points toward servers built for hotter rooms, with performance targets that make high-temperature operation practical rather than exceptional.

The obstacle is that the saving is not automatic. Hotter air can raise server power draw, so a data center must gain more from cooling savings than it loses through less efficient hardware. That trade-off varies by location, workload and equipment age, which means the global average hides local decisions. The path forward is therefore both technical and commercial: better thermal design, clearer performance standards, and incentives that reward total energy use rather than cold air alone.

If a room can be warm without failing its machines, then the next question is not whether data centers should run hotter, but how quickly the industry will accept heat as part of the solution.