Condensation risk in a partially air side economized data center

Air side economization minimizes the usage of Air Conditioning Units (ACU) and water chiller when outside temperature falls below the operating set point of data centers. In many data centers, the relative humidity is less controlled compared to temperature; humidification or de-humidification are used only when upper (80%) or lower limits (10%) thresholds are exceeded. We present a case study of a data center where high humidity combined with abrupt cooling leads to condensation. Since servers racks cannot respond to instant decrease in temperature, the thermal lag time to reach equilibrium can create a transient condition when condensation can appear in locations where the temperature of the servers falls below the dew point within the data center. A new control algorithm is discussed based on dew point control to improve Information Technology (IT) equipment safety by minimizing corrosion and/or reducing condensation risks.