Cooling system with indirect humidity determination

A cooling system for a data center having equipment racks disposed therein, the equipment racks having electronic equipment therein, the cooling system comprising:

• a cooling unit;
• a controller coupled to the cooling unit;
• a temperature sensor disposed near an air inlet of each equipment rack at which relative humidity is to be calculated by the controller (“Temp Sensor Location”), each temperature sensor coupled to the controller;
• a relative humidity sensor disposed to sense relative humidity at a location in the data center or near an air return inlet of the cooling unit and an associated temperature sensor disposed with the relative humidity sensor, the relative humidity sensor and associated temperature sensor coupled to the controller;
• the controller measuring with the relative humidity sensor relative humidity at the location at which the relative humidity sensor is disposed and measuring with the associated temperature sensor disposed with the relative humidity sensor a temperature of air thereat;
• the controller calculating a dew point based on the measured relative humidity and temperature of air measured at the relative humidity sensor;
• the controller measuring with the temperature sensor at each Temp Sensor Location a temperature of air at each Temp Sensor Location and indirectly determining a relative humidity thereat by calculating the relative humidity thereat based on the temperature of air measured at that Temp Sensor Location and the calculated dew point.