Obviously, the lower the temperature is set for heating and the higher for cooling, the more energy is saved and energy costs reduced. Controlling the thermostat is one of the easiest and most economical ways to control your energy costs.
Recommended thermostat settings are 70E° F or lower for heating and 78E° F or higher for cooling. These settings should provide a comfortable environment within the home. Each degree higher than 70E° F can increase heating costs by 1-3%, and each degree below 78E° F can increase cooling costs by 3-5% or more.
You should also set your thermostat back (in winter) or up (in summer) whenever you will be out of the house for several hours or longer. It is a common misconception that it will take more energy to heat the home back up (or cool it back down) than was saved by setting the thermostat back. By setting the thermostat back for heating or up for cooling when you are not home or overnight, you can save as much as 10% on your annual energy bill.
Thermostats should be checked, cleaned and calibrated periodically. A good rule of thumb is to have your service contractor check the thermostat when performing annual maintenance on the system.
To make control of the thermostat easier, a setback or programmable thermostat is recommended. A programmable thermostat allows you to program the temperature of the house for different times or days and then leave the thermostat alone for the rest of the heating or cooling season. These thermostats allow you to set the temperature down (or up) during the day or overnight, but increase (or decrease) the temperature prior to your arrival or when you awake. This allows you to save energy without waking up to a cold house in winter or coming home to an overheated house in the summer. Programmable thermostats come in many varieties. They can allow for either one or two adjustments a day or multiple changes over a week. To decide the best thermostat for your needs, determine what temperature setbacks you want for your home and look for the simplest thermostat that will meet your individual needs.
If you have a heat pump system, you should review the manufacturer's specifications before purchasing a programmable thermostat. An improperly used or mismatched setback thermostat can actually increase heat pump operating costs by increasing reliance on the more expensive back-up heating elements. Most manufacturers now offer programmable thermostats specifically designed for heat pumps.