Using a small, portable space heater can be an energy efficient way to bring heat to a chilly room without having to raise the thermostat. Many people will leave a heater on a small table to heat up a room, not realizing it's the least energy efficient way of using it. Instead, place the space heater on the floor and turn it on. Since heat rises, it will warm up the cool air as the hot air rises, giving you maximum efficiency. And if you want it to be even more efficient, use the space heater with a timer so it automatically turns off after a set period of time.