There’s nothing better on a hot summer’s day than stepping into a cool building, the hum of the air conditioner in the background, the brief escape from the heat. In places without air conditioning, summer takes a fast turn for the uncomfortable, becoming stifling and sometimes even dangerous. For the two-thirds of U.S. homes with air conditioners, choosing the right air conditioning unit is crucial. As winter approaches, we turn on the heat and watch our energy bills skyrocket. It’s a necessity, but one that drains the pockets of many. In fact, heating and cooling makes up almost half of a typical home’s energy use.