A couple of years ago, I visited my older sister on the other side of the country. I spent a week with her, and was totally comfortable in her guest bedroom. Although her home is not equipped with a central cooling system, there was a window air conditioner in my room. Despite outdoor temperatures in the high eighties, the room was perfectly cool. I had a little remote control which allows me to make adjustments without even getting out of bed. With a tap of my finger, I could raise or lower temperature, regulate fan speed and even target humidity levels. At the end of the a busy day, I was always eager to crawl into bed. I had no trouble sleeping and always felt rested in the morning. This past winter, I decided to visit my sister for another week. My stay was not as comfortable this time. Her house is outfitted with a forced air furnace with a single thermostat. Because of only the only thermostat, every room is heated to the same temperature. The guest bedroom was always slightly overheated, and I’d wake up damp with sweat. Plus, without the air conditioner drowning out other sounds, I had a great deal of trouble sleeping. I heard the wind chime outside my window, the furnace kicking on and off, and the dog barking. I even heard my sister snoring in her bedroom on the other side of the wall. My sister definitely needs to update her heating system to zone control. The guest bedroom is usually empty, and yet she’s paying to heat it all winter long.