About "Ask the Energy Expert"
Craig Muccio runs FPL's Conservation Research & Development Program and crunches the numbers to figure out how you can save by managing your energy use.
Your questions on energy-related topics can be submitted anytime to our Ask the Energy Expert blog. Just click here to submit your question, and if chosen, it will be answered here
Asked on: August 31, 2015 by Patricia S., Boca Raton
If no one is home during the day, should we turn the A/C off or keep it on at a higher temp?
Great question, I’m sure many of our customers wonder the same thing. In this case, your savings will be maximized if you turn off the A/C when you are not home. However, depending on how much your home heats up during the day and how fast your A/C can cool it down, turning it off completely may make you uncomfortable for a while after you get home.
Thermostats & Settings
If you only have a manual thermostat, you will have to experiment with the daytime temperature setting that works best for you. If you have a programmable thermostat, you can try setting the temperature as high as it goes while you are out with it programmed to return to your preferred temperature an hour before you get home. If that is not sufficient to pre-cool your home, try resetting your A/C to return to your preferred temperature sooner or try a lower temperature while you are out during the day. Some newer thermostats even let you check the temperature inside your house and remotely change the thermostat setting from your computer or mobile device before you head home. Now, if you are wondering what temperature to leave the A/C on for your pet during the day, I think I will leave that question for your vet to answer!
Do you use more than one air conditioner to cool your home? If so, the same suggestions apply. When you are home, you can save by running only the A/C unit in the part of the house you are using at the time. Just remember that cooling two separate zones works best if you can close off the area of the home where you are running the air conditioner from the other part where the A/C is turned off.
Risks of Mold
Some customers wonder if setting the thermostat too high in the daytime might encourage mold growth. Humidity is highest during the cooler early morning hours. As temperature rises during the day, the relative humidity actually goes down, which discourages mold growth. As long as your A/C runs for a few hours a day, your home should be sufficiently dehumidified to fend off that musty smell of mold.
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