Systems, devices, and methods including: a fresh air damper configured to receive outside air via an input plenum； a mixing chamber configured to receive the outside air from the fresh air damper and exhaust from one or more chillers, where the outside air and the exhaust are mixed in the mixing chamber； a blower section comprising a blower, where the blower section is configured to receive mixed air from the mixing chamber, and where the mixed air from the mixing chamber is received through a mixing damper； and a relief damper connected to at least one of: the mixing chamber and the blower section via a relief ducting, where the relief damper allows a release of at least one of: the fresh air, the exhaust, and the mixed air to an ambient environment
