A programmable thermostat is an essential device used to save on heating and cooling costs. When used effectively a thermostat can save as much as 10% of cooling costs. The thermostat automatically regulates the temperature of your house at different times of the day. This helps to ensure that the right amount of heating is applied at the right time. For example, furnaces can automatically be programmed to reduce heat once you are in bed and to increase the heat before you get up, subsequently decreasing it when you leave for the day. Thermostats can be used similarly in the summer to save energy.