How to keep a room or house cool without air conditioning in Florida

Keep the sun's heat out

The DOE's Energy Saver Guide says shading can reduce heat gain from the sun.

The DOE's Energy Saver Guide says, "During summer, keep the window coverings closed during the day to block the sun's heat." It also says to close draperies on windows receiving direct sunlight to prevent heat gain. For new curtains, it suggests medium-colored draperies with white plastic backings to reduce heat gain.

Outside the glass works too. The same guide says to install awnings on south- and west-facing windows to create shade.

The guide also says trees, shrubs, and groundcover plants can shade the ground and pavement around the home. That cools the air before it reaches your walls and windows. It adds that shrubs and trellised vines can also shade walls and windows.

It notes the right landscaping plan depends on your climate and your home's microclimate. Microclimate means the conditions in the area immediately surrounding your home.

Use fans the right way, and know their limit

The DOE's Home Cooling 101 guide says fans circulate air and create a wind chill effect that makes people more comfortable.

The same guide says, "Turn off your fans when you leave the room -- fans cool people, not rooms."

For ceiling fans, the DOE's Energy Saver Guide says to run the fan in a counterclockwise direction in summer to create a wind chill effect.

The CDC's heat page says, "Use fans, but only if indoor temperatures are less than 90°F." It then warns, "In temperatures above 90°F, a fan can increase body temperature."

A second CDC page, written for people without air conditioning, says not to rely solely on fans. It says that while electric fans might provide some comfort, when temperatures are really hot, they won't prevent heat-related illness.

Cut the heat you make inside

The CDC says to use your stove and oven less to maintain a cooler temperature in your home.

The DOE's Home Cooling 101 guide says, "Don't heat your home with appliances." On hot days, it suggests an outdoor grill instead of your oven.

When you do cook or bathe, move that heat outside. The same DOE guide says to use the bathroom fan when you shower or bathe. It also says to use a range hood when cooking, because this helps remove heat and humidity, which is moisture in the air.

The DOE's Energy Saver Guide adds a limit. Unless a fan is designed for continuous operation, it says to turn off kitchen, bath and other exhaust fans within 20 minutes after you are done cooking or bathing.

Opening windows: when it helps in Florida and when it does not

The DOE's Home Cooling 101 guide calls ventilation the least expensive and most energy-efficient way to cool a home. Ventilation here means bringing outdoor air in, for example through open windows. It says a simple strategy is opening windows to create a cross-wise breeze.

The same DOE guide says one way an air conditioner makes us feel cooler is by reducing the amount of moisture in the air.

Humidity also changes how hot you feel. The National Weather Service (NWS) office for Tampa Bay says sweat cools the body as it evaporates. It says the body cannot regulate its temperature if the perspiration is not able to evaporate. In its words, the human body feels warmer in humid conditions.

The NWS Tampa Bay office says the rainy season runs from May 15 to October 15 for Southwest Florida and from May 25 to October 10 for the rest of West Central Florida. It describes that season as warm, humid conditions with frequent showers and thunderstorms.

The University of Florida's extension service, called UF/IFAS Extension, gives Florida-specific advice. It says many areas of northern Florida can use natural ventilation in fall and spring. It adds that this can also work elsewhere in Florida, depending on personal comfort.

It also warns that long periods of high relative humidity can eventually lead to mold problems, especially in stagnant air spaces such as closets. Its test is to watch for things like leather shoes in the back of a closet. If they start to mold, it says to close your windows and run the air conditioner a little more.

UF/IFAS also suggests indoor and outdoor humidity and temperature monitors to judge if it is the right time for natural ventilation.

Whole-house fans, cool roofs and swamp coolers

The DOE's Home Cooling 101 guide says a whole-house fan pulls air in through windows and pushes it out through the attic and roof. The DOE's Energy Saver Guide says to use it during cooler times of the day.

A DOE Building America guide from 2012 says average nightly lows at or below 65°F and an average monthly daily temperature range of 20°F or more are a good indication that ventilation cooling would be beneficial.

That guide did not evaluate hot-humid climates because of their low daily swings and high humidity. It says ventilation cooling is not recommended where summer night air commonly has a higher total heat content, counting its moisture, than the indoor air you want. It says there may be spring or fall days in hot-humid climates when it is very useful, but that it is harder to justify the cost there because the air conditioner has to run more to remove moisture.

If you are thinking of adding one, the DOE's Home Cooling 101 guide says professionals should install whole house fans to ensure proper sizing and safety. Adding a fan wired into the house is electrical work, so use a licensed electrician.

The roof matters too. The DOE's Energy Saver Guide says standard roofs can reach temperatures of 150°F or more in the summer sun. It says a cool roof reflects sunlight and efficiently emits heat, and that a cool roof doesn't have to be white.

Swamp coolers, also called evaporative coolers, cool air with evaporating water. The DOE guide says they work well where the air is hot and humidity is low. See our guide to evaporative coolers in Florida.

When it is a health question, not a comfort question

The CDC says to prepare ahead of time for hot days, especially if air conditioning is not available in your home.

It says to drink more water than usual, and don't wait until you're thirsty to drink. It says to take cool showers or baths. It suggests spending some time at a shopping mall or public library, because even a few hours in air conditioning can help.

To find a cooled place, the CDC says you can dial 2-1-1 or contact your local health department or emergency management agency. If you need financial assistance, it says to contact the Low Income Home Energy Assistance Program (LIHEAP).

The CDC lists symptoms of overheating, including muscle cramping, shortness of breath, dizziness, headaches, weakness and nausea. It says to seek medical care immediately for symptoms of heat-related illness.

The CDC says some groups may have to take additional action on hot days, including people 65 or older, infants and young children, pregnant women, people with heart disease, and people, especially children, with asthma. It also says many medicines can make you dehydrated or overheated on hot days. Check on neighbors who live alone.

Our guides on an AC not blowing cold air and an AC that can't keep up with the heat cover what to check next. For a single room, a window air conditioner is another option.