Changes

In this case, we could put a 5- x 5-inch intake vent at one end of the salon and a vent of the same size at the other end with an exhaust fan driving 2 ft/s.

A water-based chiller provides air conditioning. The chiller circulates chilled water through a water distribution system to the cabins, to cool them in summer. All pipes should be insulated to prevent condensation. (Similarly, if you opt for forced air, the ducts should be insulated.)