Heat waves are a leading cause of heat-related illness – and even death. Not all methods for keeping cool are effective during a heat wave. Using a fan can be more harmful than helpful when indoor air temperatures are hotter than your body temperature.
Should I use a fan?
| When indoor air temperatures are cooler than about 95 °F: Use a fan when outdoor air temperatures are cooler than indoor air temperatures. (Fans in windows can blow cooler air into a room from outside). Fans do not cool the air, so air currents flowing over the body must be cooler than your body temperature to cool you down. | When indoor airtemperatures are hotterthan about 95 °F: Fan use may cause your bodyto gain heat instead of lose it.On very hot, humid days, sweatevaporates off the skin slowerthan normal, and fans make iteven more difficult for the bodyto lose heat by sweating. It’simportant to stay hydrated andfollow other tips to get cool. |
It may be helpful to have an indoor thermometer or a thermostat with a temperature display to tell you the actual temperature inside your home. This is especially helpful if you are or care for an individual at higher risk for heat-related illness.
Check on your neighbors, friends, and family members who may be at higher risk of heat-related illness:
- Babies, young children, and adults over age 65 who are often less able to regulate body temperature, cool down from sweating, and can get dehydrated more quickly than others.
- People with mental or physical disabilities, or who are dependent on others for daily care.
- People who have preexisting health conditions, especially those who have diabetes or heart disease, have experienced a previous heatstroke, or are overweight.
- People who live alone or do not leave their homes daily.
- People who live in upper-level or top floor apartments.
- People without air conditioning.
How can I prevent heat-related illness?
- Use an air conditioner.
- If an air conditioner is not available, spend at least 2 hours in air conditioned places (shopping mall, library, cooling center, air-conditioned home of family/friend).
- If you cannot leave your residence/building, spend more time on the lower levels where it may be cooler.
- Close window blinds and curtains.
- Drink plenty of cool nonalcoholic and caffeine-free liquids.
- Close curtains and window coverings.
- Take a cool shower or bath. Place cold, damp cloths over your head, neck, armpits and body. Wear light, loose clothing.
- Limit strenuous physical activity.
- Avoid using your stove/oven.
FAQs
Electric fans may provide comfort, but when the temperature is in the high 90s, fans will not prevent heat-related illness. Taking a cool shower or bath or moving to an air-conditioned place is a much better way to cool off. Air conditioning is the strongest protective factor against heat-related illness.
How hot is too hot for a fan? ›
When indoor air temperatures are hotter than about 95 °F: Fan use may cause your body to gain heat instead of lose it. On very hot, humid days, sweat evaporates off the skin slower than normal, and fans make it even more difficult for the body to lose heat by sweating.
At what temperature do fans become useless? ›
“Fans at any temperature up to 104°F, where there is some kind of humidity, are beneficial,” says Jay. “But as the temperature goes higher, if it's dry then fans are progressively less useful and potentially detrimental.”
Do fans actually cool down a room? ›
A ceiling fan does not actually lower the overall temperature in a room, but it can definitely make a space feel cooler. Ceiling fans primarily work through something called a wind chill effect. Essentially, the moving air across your skin helps to evaporate sweat at a faster rate.
How do you use a fan in hot weather? ›
To really cool down a room with a fan, place a deep dish of ice in the front of it to whip up the water mist and chill the breeze. You can also point a box fan out of an open window in the evenings – this pushes the hot air out instead of just blowing it around the room. Cool down a room with a fan.
Can a fan make your room hot? ›
What happens to the overall temperature of a room when a fan is operating in it? When a fan operates in a room, it does not decrease the room's overall temperature. Instead, the fan moves air around, which can add heat to the room due to the motor's operation converting electricity into heat.
Why is my room so hot even with the fan on? ›
Dirty air filter—A dirty filter restricts airflow, not letting your home get enough cool air. Closed vents—Closed vents in rooms can cause them to be hotter than other rooms. Open windows—Your conditioned air can flow out of open windows, leaving uneven temperatures in your home.
Does putting ice in front of a fan work? ›
According to the GHI, placing a bucket of ice in front of a fan as a homemade AC unit is just as effective. 'As the air passes over the ice it will be chilled and will circulate refreshingly cold air around the room,' they explain.
Do you put ice in front or behind a fan? ›
To maximize the cooling effect, it's important to have the non-oscillating fan on the ground or pointing toward the area you'd like to cool down. You want to put the ice in front of the fan so the cool breeze from the frozen ice cubes will reach you when the fan is blowing.
Where should I put my fan to cool my room? ›
Play with strategic placement
Alternatively, Beatrice suggests placing a fan in your window and another in the door to pull cool air into the room and push hot air outwards. 'It will also help to reduce the humidity levels in the room, making it more comfortable to be in,' the expert says.
If you put a wet towel in front of the fan the moisture in the fan will evaporate cooling the air, but raising the humidity. It is the same principle as an evaporative or swamp cooler.
Do fans use a lot of electricity? ›
A typical fan consumes between 50 and 100 Watts per hour. Above everything, this is an interesting saving, when you consider that standard air conditioning consumes around 700 watts per hour. This means that not only can you save on installing expensive air con, but your electricity bill will also benefit.
Do fans cool a room or make it hotter? ›
Fans do not cool a room. Turn off a fan when you leave the room. Leaving a fan running in an empty room makes the room hotter (because the fan uses energy). Use fans to send warm air out of a room; do not use them to pull cool air into a room (because you also send the heat of the fan into the room).
How much colder does a fan make a room? ›
Understanding the Wind-Chill Effect
Wind chill refers to the perceived decrease in air temperature felt by the body as a result of air movement. Even if the actual temperature in a room remains the same, the wind-chill effect created by a ceiling fan can make you feel up to 4 degrees Fahrenheit cooler.
Why is my fan not cooling my room? ›
If the ceiling fan isn't cooling the room, it might be because the fan isn't the correct size. Install a ceiling fan that's large enough for the room. Larger fan blades move more air for only a fractionally greater power draw.
Can you leave fan on all night? ›
Consumer safety charity, Electrical Safety First, says that leaving your fan on at night could put you at risk if a fault occurs within your device while you're sleeping. Yup, we're talking a one-way ticket to a house fire.
