Method and apparatus for ventilating an interior space, such as a large industrial structure with at least one bay opening. A ventilation system includes an array of M by N fans stacked into a two dimensional (2D) array. A rigid frame supports the array. A seal assembly provides a nominally fluid-tight seal between an outer perimeter of the array and the bay opening. A locking assembly mechanically couples the frame to the bay opening. In some cases, a bay door can be partially retracted and attached to a top of the frame. In other cases, the bay door may be fluidically permeable (e.g., a chain, a screen, etc.) and the array is secured behind a fully closed door. Cooling air is directed out the bay opening at a suitable time, such as overnight. A soft-start motor capability can be used to initiate operation of the array.