A container (10) for transporting a load in conditioned space air (14), where the container includes a number of walls (16, 18, 20, 22, 24, 26) defining a closed conditioned space with an ambient air intake opening (54) and a conditioned space air exhaust opening (56) provided on one of the container walls; a temperature control system (28) for controlling the temperature of the conditioned space air; an ambient air exchange system (12) having a door (74) movable relative to the exhaust and intake openings to thereby change the rate that conditioned space air is exchanged with ambient air, and a motor (62) for repositioning the ambient air exchange door. The container also including a container controller (30) in signal transmitting relation with the air exchange door repositioning motor. The controller sends signals to the repositioning motor to move the ambient air exchanged door to a position which produces the required ambient air exchange rate to preserve the load.