Use programmable thermostats to adjust heating and cooling when rooms are unoccupied, saving you energy and up to $180 a year. In the summer, keep your home warmer than normal when you are away, and set the thermostat to 78°F (26°C) only when you are at home and need cooling. Try setting your thermostat at as high a temperature as comfortably possible and ensure humidity control if needed. The smaller the difference between the indoor and outdoor temperatures, the lower your overall cooling bill will be.

Although thermostats can be adjusted manually, programmable thermostats will avoid any discomfort by returning temperatures to normal before you wake or return home. Raising your thermostat setting in the summer to a higher interior temperature will slow the flow of heat into your house, saving energy on air conditioning.

Avoid placing lamps or TV sets near your room air-conditioning thermostat. The thermostat senses heat from these appliances, which can cause the air conditioner to run longer than necessary. Also avoid setting your thermostat at a colder setting than normal when you turn on your air conditioner.  It will not cool your home any faster and could result in excessive cooling and, therefore, unnecessary expense. A common misconception associated with thermostats is that a furnace works harder than normal to warm the space back to a comfortable temperature after the thermostat has been set back, resulting in little or no savings. In fact, as soon as your house drops below its normal temperature, it will lose energy to the surrounding environment more slowly.

https://www.energy.gov/energysaver/thermostats

https://www.nationalgridus.com/MA-Gas-Home/Energy-Saving-Tips/Heating-Cooling

https://www.energy.gov/energysaver/spring-and-summer-energy-saving-tips