For a device that’s been widely used since at least 3,000 B.C., the fan still generates controversy – particularly when it comes to whether or not it saves energy.

With air conditioning the norm these days, fans are rarely an either/or question when it comes to cooling your home. More often, they’re used to complement your HVAC system rather than to replace it.

And it’s true: ceiling fans require much less energy than even the most efficient HVAC system. That’s not up for debate. But whether ceiling fans actually help you conserve energy depends largely on how you use them. So here are some tips on how to maximize the efficiency of your ceiling fans to offset your HVAC usage.

Bigger is Better

To get more air movement, you can do two things: increase the fan speed and increase the blade size. Both increase energy use, but increasing the fan speed increases the energy use a lot more than increasing the blade size. All things being equal, efficacy increases when you increase the blade length. After making sure you adhere to all of the recommended clearances in respect to the size of your room, it’s worth investing in the largest fan your space can accommodate.

Slower is Smarter

Another thing you’ll notice when you look at efficacy ratings is ceiling fans are more efficient when they’re operating at lower speeds. It’s important to operate your fan at the lowest speed that keeps you comfortable. It may be tempting to leave your fan on high, but that actually increases the energy required to power the motor, which can elevate the temperature of your room as the motor produces heat to run.

Cool People, Not Rooms

You may be surprised to learn that fans don’t actually lower the temperature of your home. Instead, the biggest benefit of fans is their wind chill effect. A fan will make you feel cooler. Moving air accelerates the rate at which perspiration evaporates from your skin. That’s why you may feel cooler thanks to a gentle breeze, even though temperatures don’t necessarily fall on a windy day.

Consider raising the temperature on your thermostat while enjoying the wind chill effect that your ceiling fan provides. Also, be sure to turn off your fan when you’re not in the room. Since the fan is designed to make you feel cooler instead of your room, there’s no reason to leave the fan running when you’re not around.

A ceiling fan may not guarantee a lower energy bill. That said, there’s reason enough not to ignore technology that has provided relief from high temperatures for thousands of years. Be smart about the fan you choose and how you operate it, and the cool breeze you generate will help offset your HVAC use and reduce your home energy consumption.