Do programmable thermostats save energy?
The U.S. Department of Energy estimates that programmable thermostats save one percent on energy bills per degree set-back (for eight hours). So, if you set your thermostat back by 10° each night (or up by 10° for eight hours each day during the cooling season), a 10 percent annual energy savings should be expected. Higher savings will occur in more extreme climates.
Programmable thermostats can improve comfort and save money by automatically setting the thermostat at different levels for different times of the day and week. They take the homeowner out of the equation by automatically setting the thermostat down when the house in unoccupied and turning it back up so the house is cozy for the homeowner’s return. The thermostats can even “learn” how long it takes for the house to warm up, and adjust when the heating system (or cooling system) comes on based on the interior conditions. Humidistats are now available to control HVAC systems based on temperature and humidity, keeping occupants more comfortable and systems operating most efficiently.