BreezeBox Portable AC Reviews : To pick the privilege fueled machine for the business, consider the floor plan and protection of the room. This will help decide the British Thermal Unit (BTU) rating of the unit, which ought to be a main factor in buying cooling units. Compact units are evaluated in BTUs. The higher the BTU rating, the more force the machine will have. For instance, a little room of 150 square feet will just require a BTU rating of 7,500, while a bigger room of 500 square feet will require a BTU rating of 14,000.