Homes account for more than 10 percent of the total energy consumption in America, including transportation. About half of the residential energy consumed is for heating and cooling, with the rest going for lighting, heating water, appliances, televisions and computers.
Each degree cooler a house is kept in a heating season (winter), or warmer in a cooling season (summer), translates to a 5 percent energy saving. So shifting consumption patterns, say, four degrees on average can mean energy savings of 20 percent, experts say.
Since the average home spends $1,000 to $1,500 a year on heating and cooling, that would translate to $200 to $300 in lower energy bills. It would also mean fewer power plants built and lower carbon emissions.
From an article about the soon-to-be-introduced Nest thermostat. It comes from former Apple employees, so I'm inclined to believe their trust in design and purpose. I'll look into the device when it's available.
Even more information and pictures at Fast Company.