Abstract: Temperature, humidity, and pressure control systems and methods for enclosed spaces, including data centers. In some embodiments, the rotational frequency of the air supply fans is controlled based on a pressure associated with the enclosed space. In some embodiments, the rotational frequency of the air supply fans is controlled based on a pressure differential between an inlet region and an exhaust region within the enclosed space. In some embodiments, air within the inlet region is segregated from air within the exhaust region. In some embodiments, the cooling capacity of the cooling equipment is controlled responsive to a temperature associated with the enclosed space. In some embodiments, the cooling capacity is controlled based on a temperature associated with the inlet region of the enclosed space. In some embodiments, the humidity within the enclosed space is controlled.