What is the best device to cool a room?

The best device to cool a room depends on room size, budget, and whether you can install permanent equipment, but for true temperature reduction, an air conditioner is the best device. For whole house cooling, central air conditioning is most effective, as it removes heat and humidity and distributes cool air evenly. For single rooms, a window air conditioner or a portable air conditioner with 8000 to 14000 BTU is the most effective because it contains a real compressor that actually lowers air temperature, not just circulates air. Window units are more efficient and cheaper to run than portable units, but portable units require no installation beyond a window hose. If you cannot use AC due to cost or installation limits, an evaporative cooler is the next best in dry climates, as it cools air by 10 to 15 degrees using water evaporation. For personal comfort without lowering room temperature, a ceiling fan combined with a box fan or air mover provides excellent wind chill and uses very little electricity. High-velocity air movers are excellent for quickly moving cool air from an AC room to a hot room. For energy efficiency, using a programmable thermostat with ceiling fans allows you to set AC higher and save 20 to 30 percent. The best overall strategy is a properly sized AC unit for temperature reduction plus fans for air circulation and personal cooling, as fans alone cannot lower room temperature.