In the summer, to maximize energy savings from your air conditioner (or your heat pump, in cooling mode…), you can adjust the thermostat up to 5º-15ºF (3ºC-8ºC) for the periods you are away from home.
Thermostat temperature settings for cooling
The first step, when programming a thermostat for summer energy savings, is to define the right temperature settings.
Be cautious, when setting up the thermostat. Incorrect settings may increase your energy consumption, instead of providing energy savings.
The EPA recommends that you set your thermostat to 78º F (26º C) degrees; that's the summer standard temperature: the temperature for when you are at home, awake. That's a good starting point for energy savings.
Some people like it, and wearing light clothing can help… But some people might think 78ºF/26ºC degrees is too warm; just remember that the lower your thermostat is set, the more energy you will consume...
For the periods of time when you are away from home, consider 5ºF-15º F (3ºC-8ºC) above the standard setting. Each degree will reduce your cooling bills by 1% or more.
As for the periods of time when you are asleep, consider using the standard summer temperature (78ºF/26ºC), mentioned above; most people like to sleep at this temperature, but if you feel comfortable with higher temperatures, say, 80º or 82ºF (27-28ºC), go ahead; it will provide higher energy savings.
Also consider an adjustment time period: the time that your cooling system needs to reach the standard temperature (78ºF/26ºC) when you return home or get up in the morning (the blue areas in the table below). If you usually return home at six in the afternoon, the thermostat can be programmed to automatically adjust your home's temperature thirty minutes or so earlier. Overriding your programmable thermostat settings
Modern programmable thermostats allow you to manually override a setting. without affecting the rest of the daily or weekly programs.
Once defined the temperatures to use, you just have to apply them to the periods when you are at home (awake and asleep) and away.
You may get something like the table below.
You can now enter the thermostat settings; just check your owner's manual for instructions regarding how to enter the data...