If the unit is too large, it will cool the room quickly, but remove less of the moisture, leaving the room with a damp, clammy feeling. To determine what size you need, the U.S. Department of Energy suggests multiplying the square footage of the space to be cooled by 20. If the room is heavily shaded, reduce capacity by 10 percent. If the room is very sunny, increase capacity by 10 percent. And if the unit is for a kitchen, increase capacity by 4,000 BTUs an hour.
Energy use creates pollution.
By increasing the efficiency of central air-conditioning units being installed, and by properly sizing equipment, energy use can be reduced dramatically.