Server farms are increasingly important in keeping modern society running, but they’re massive energy hogs. Data centers’ energy use per square foot can be up to 100 times that of typical office buildings. But operating data centers at a higher temperature could save up to 56% of cooling energy worldwide, according to a new study.
Cooling accounts for over one-third of data center energy consumption. Lots of research has focused on how to make cooling more energy efficient. The new study flips the script and suggests redesigning servers so that less active cooling is needed.
Early servers overheated easily, and data centers were kept so cold that technicians had to wear parkas. That legacy has led to an assumption that colder is better when it comes to data center operation. Advances in technology have produced servers that are much more robust and can run at over 30 °C (86 °F), but most data centers currently operate at 20-25 °C (68-77 °F).
Data centers are kept cool by running air heated by the server operation over coils of water to cool it. The water in the coils is kept cold either using chillers or by taking advantage of colder outside air. Lots of data centers today are built in cold climates to enable the latter process, which is known as free-cooling and uses much less energy compared to chillers.
In the new study, researchers asked what it would take to push the use of free-cooling to the absolute maximum. They used weather data from 57 cities to model the operation and energy use of data center cooling systems across 19 climate zones worldwide.
With an operating temperature of 41 °C, data centers all over the world could rely almost entirely on free-cooling year-round, the researchers report in Cell Reports Physical Science. They dub this the ‘global free-cooling temperature.’
Data centers operated at 41 °C could use 13-56% less cooling energy compared to data centers kept at 22 °C, depending on the climate zone. Server farms in cold climates already make substantial use of free-cooling, so there’s less opportunity for energy savings.
The data center temperature that permits 100% use of free-cooling depends the temperature and humidity at a given location. For example, the local free-cooling temperatures are 39 °C (102.2 °F) for Beijing, 38 °C (100.4 °F) for Kunming, and 40 °C (104 °F) for Hong Kong.
In order for data centers to operate at 41 °C, engineers will have to develop servers that are reliable, don’t lose computational efficiency, and don’t show increased energy consumption due to activation of built-in cooling fans at that temperature.
Some of the most advanced servers available today can already operate at maximum temperatures of 40 °C or 45 °C. However, these machines are very expensive and are not in wide use.
The findings provide server engineers and data center designers a concrete goal to work towards in developing the next generations of servers and data centers, the researchers say.
Source: Zhang Y. et al. “The global energy impact of raising the space temperature for high-temperature data centers.” Cell Reports Physical Science 2023.
Image: ep_jhu via Flickr.
