Up to 60% of your energy bills are controlled by your thermostat. So shouldn't it help to save you money? The Nest does. It saves energy because it learns from you. It knows the temperature you like your home to be. It turns itself down when you are away. It even learns how long your home takes to warm up and cool down. The Nest also shows you when you are saving money through the Nest energy saving leaf    . This is how the Nest saves energy.