These Portable Air Conditioners Come In Several different Sizes For Many different cooling applications - home, office, lan room, garage they are portable. Most air conditioners have their capacity rated in British Thermal Units (BTU). Generally speaking, a BTU is the amount of heat required to raise the temperature of one pound (0.45 kg) of water 1 degree Fahrenheit (0.56 degrees Celsius). Specifically, 1 BTU equals 1,055 joules. In heating and cooling terms, 1 "ton" equals 12,000 BTU. The Energy Efficiency Rating (EER) of an air conditioner is its BTU rating over its wattage. For example, if a 10,000-BTU air conditioner consumes 1,200 watts, its EER is 8.3 (10,000 BTU/1,200 watts). The portable air conditioners listed below, excluding the window mount units require the use of a window vent kit like the one pictured here. Click here for Portable Air Conditioner FAQ's. All Portable Air Conditioners Require An Exhaust Hose To An Outside Source.