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Guide · OBC Air & Heat

Best Thermostat and Humidity Settings for Florida Homes

What DOE suggests for summer thermostat settings, the indoor humidity target, fan Auto vs. On, and what to set when you're away from a Space Coast home.

The basic rule: as high as is comfortable

DOE's Energy Saver guide puts it simply: in summer, set your thermostat "as high as is comfortable" when you're home and awake, and raise it when you're sleeping or away. Raising it 7–10°F for 8 hours a day can save "as much as 10% per year" on heating and cooling (DOE Energy Saver Guide). DOE's heating and cooling guide suggests 78°F for summer when you're not home (DOE Guide to Home Heating and Cooling).

There's no single "right" number for every home. Use these as starting points and adjust:

  • Home and awake: as high as you're comfortable.
  • Away for the day: higher. DOE uses 78°F as its example.
  • Asleep: higher, if you're comfortable.

A programmable or smart thermostat makes this automatic, and it can bring the temperature back down before you get home. DOE notes that ENERGY STAR certified smart thermostats are independently certified to deliver energy savings, based on field data.

Use ceiling fans to feel cooler

DOE says a ceiling fan lets you raise the thermostat about 4°F "without any loss in comfort." Run it counterclockwise in summer, and turn it off when you leave the room (DOE Energy Saver Guide). Fans cool people, not rooms.

Fan "Auto" vs. "On"

Set the thermostat fan to Auto. DOE recommends Auto unless an indoor air quality professional has set up your system to run continuously for health reasons.

In Florida, there's a second reason. Researchers at the Florida Solar Energy Center (FSEC) found that when the fan keeps running after the compressor stops, water on the cold coil evaporates back into your home. In one test, 19% of the moisture removed during the cooling cycle went back into the room, and indoor humidity was higher in fan "On" mode (FSEC-PF-118-87).

The humidity target

EPA advises keeping indoor humidity below 60%, ideally between 30% and 50% (EPA: Mold, Moisture and Your Home). High humidity raises the risk of mold (EPA: Care for Your Air).

A simple humidity meter from a hardware store will tell you where you stand. If your home feels cool but clammy, your system may not be removing enough moisture. Common causes include an oversized system, airflow problems and fan settings. See Sizing an AC for Florida Humidity and our humidity and indoor air quality page.

Settings for when you're away

For a day or a weekend: raise the setpoint, keep the fan on Auto and let the system run.

For weeks or a season: be careful. Don't turn the AC off, and don't assume a very high setting is safe. FSEC tested vacant-home strategies in Brevard County homes, including houses on Merritt Island and in Cocoa. Setting the AC to 85°F (fan Auto) gave "generally poor results" because the system didn't run long enough to remove moisture on cooler or cloudy days. Even 83°F didn't ensure good humidity control. Running the AC at a lower setting for a few hours a day gave promising but mixed results, depending on how leaky the house was (FSEC-CR-1487-04). UF/IFAS advises setting the AC no higher than 85°F when closing a seasonal home (UF/IFAS: Closing Your Seasonal Home).

The safe takeaway: if a home will sit empty, plan for humidity control, not just temperature. A smart thermostat with humidity readings, or a dehumidifier on a humidistat, can help. Ask us what fits your home. Hurricane season adds its own steps. See Hurricane Prep and Post-Storm AC Checks.

If you have a heat pump

DOE cautions not to set back a heat pump's thermostat manually if it causes the backup electric-resistance heat to come on, because that heat costs more to run. Use a smart or programmable thermostat designed for heat pumps (DOE Energy Saver Guide). More in Heat Pumps in Brevard.

Small businesses

The same ideas apply to a shop, office or other light commercial space. Schedule cooler setpoints for open hours and higher ones after closing. Keep humidity in mind overnight and over long weekends, especially in buildings with stock or paper records.

The next step

Need a new thermostat, or a system that controls humidity better? We look at the home or building first, then quote in writing. See thermostats.

Firefighters, law enforcement, EMS and paramedics, healthcare workers, teachers, ministry, government employees and military (active and veterans) can get 10% off the total, up to $2,500, on new units and repairs through our Local Heroes program. Family members of eligible heroes qualify too. It can't be combined with other offers.

Frequently asked questions

What should I set my thermostat to in Florida summer?

As high as is comfortable when you're home, and higher when you're asleep or away. DOE suggests 78°F for summer when you're not home. Raising it 7–10°F for 8 hours a day can cut heating and cooling costs by as much as 10% a year, according to DOE.

Should my AC fan be on Auto or On?

Auto. DOE recommends Auto for most homes. Florida Solar Energy Center research found that running the fan continuously puts moisture from the coil back into the house and raises indoor humidity.

What indoor humidity should I aim for in Florida?

EPA recommends keeping it below 60%, ideally between 30% and 50%. A humidity meter can show where your home stands.

Can I turn off my AC when I leave for the summer?

It's not recommended in Florida. Without cooling, humidity can build up and raise the risk of mold. FSEC testing in Brevard County homes found that even an 83–85°F setting often didn't control humidity well. Plan for humidity control, and ask us what fits your home.

Do ceiling fans let me raise the thermostat?

Yes. DOE says a ceiling fan allows about 4°F higher with no loss in comfort. Turn fans off when you leave the room.

Will a smart thermostat help?

It can make setbacks automatic. DOE notes that ENERGY STAR certified smart thermostats are independently certified, based on field data, to deliver energy savings. Heat pump owners should choose one designed for heat pumps.

Sources

  1. DOE Energy Saver Guide
  2. DOE Guide to Home Heating and Cooling
  3. FSEC-PF-118-87
  4. EPA: Mold, Moisture and Your Home
  5. EPA: Care for Your Air
  6. FSEC-CR-1487-04
  7. UF/IFAS: Closing Your Seasonal Home

Written by OBC Air & Heat, Space Coast, Brevard County, FL. State Certified Air Conditioning Contractor, License No. CAC1825377. General information only; your system and home are reviewed before any recommendation.

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