How to Ensure Optimal Relative Humidity in Data Centers?
In data centers, cooling and humidity control are complementary tasks: while excessively low humidity (below 20%) can lead to electrostatic discharges, excessively high humidity (above 80%) can cause corrosion, short circuits, and mold growth. Both extremes can lead to serious malfunctions and costly repairs, so the focus is not on achieving a fixed value, but on maintaining a constant, fluctuation-free environment.
Since 2008, ASHRAE has recommended a relative humidity of 20–80%, but emphasizes that modern IT equipment can operate in the 10–90% range. The most important thing is that the humidity does not fluctuate significantly, as critical components—especially A1-rated servers and infrastructure—are sensitive to sudden changes. The combination of temperature and humidity conditions must be selected to meet the operating requirements of each equipment class.
Dew point monitoring is becoming an increasingly popular solution: it monitors in real time at rack level when the air reaches the condensation threshold (optimal dew point: 5–15 °C). This allows not only the entire data center but also the moisture risk of individual server racks to be accurately monitored, enabling targeted intervention when necessary.
In liquid cooling systems, humidity control is less
critical, as the chips operate in a direct water-cooled environment.
Nevertheless, care must be taken to avoid condensation, mold growth due to high
humidity, and corrosion caused by acidic contaminants dissolved in the air
(e.g., chlorides, sulfides). Free cooling systems can be energy-intensive in
areas with particularly high external humidity, as the intake air must be
pre-dried.
Finally, humidity and temperature control is an
energy-intensive process, so the design must take into account the climatic
conditions of the site, the humidification and dehumidification capacity, and
sustainability considerations. A combination of strategic location,
energy-efficient equipment, and stable operating parameters ensures that the
data center will operate reliably, economically, and in an environmentally
friendly manner over the long term.