GYR Tips for Ventilation, Air Flow and Fans

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With the increased availability of air conditioning, many of us forgot about, or became wary of, the natural cooling power of our tropical breezes.

 
Illustration of Cross section of house to view ventilation system  Check your ducts for air leaks.

A common reason for overworked HVAC systems and inflated energy bills are leaky air ducts. Ducts are like the roadways of your air conditioning system. You want air to travel freely and efficiently through the ducts to each room, but you do not want “exits” where they should not be. Holes and poorly connected ducts can be the cause of leaks. It is worth the effort to check your ducts periodically, or hire a professional to do so. Check this link to access Energy Star information on ducts, such as a Frequently Asked Questions and a Do-It-Yourself brochure. Florida Power and Light customers can also take advantage of air duct assessment and repair information, tools, and rebates offered to them. 
 
 Illustration of weather strip and caulk door areas
Weather-strip and caulk doors and windows to keep the right amount of cool air in and warm humid air out, but ventilate when necessary.

It is important to have proper air flow in a building. Air leaks can affect indoor air quality, the occupant’s health, and even the structure itself. The key is to balance air flow for optimal comfort, and in our climate to ensure that mold does not form. While anything from roofs to recessed lighting can be the source of an air leak, windows and doors are the common sources of unintended air flow. They should be checked and resealed as part of a maintenance schedule. Fireplaces, though less common in our area, can also be a source of leaks. Damper handles should work properly. Rooms that are a source of moisture (such as the bathroom and kitchen) should be mechanically ventilated using exhaust fans if a window is not available. And do check the areas around recessed lighting to be sure that fixtures fit tightly. Consult professionals to assist, or check this comprehensive guide to air sealing from the U.S. Department of Energy’s Building America Best Practice Series. Energy.gov provides a DIY Guide.
 
 University of Florida IFAS Extension  Install ceiling fans, check their rotation seasonally, but only run them when you are in the room and adjust thermostats accordingly.

While ceiling fans do not actually lower the temperature of a room, they do make it feel cooler. As a result, when running fans, you can raise your thermostat by as much as four degrees and still feel comfortable. These combined actions have the potential to shave more than four percent off your cooling bill (and potentially much more), but using fans without changing your thermostat will actually cost you money. Because fans only make it feel cooler, it is also important not to run them all the time. Follow this rule: Fans cool people, not rooms. Always turn off a fan, along with your lights, when you leave a room. And, always choose an Energy Star-rated fan. For existing fans, check that they are set to turn the appropriate direction for the season. On hot days, your fan should rotate counter-clockwise (also called forward) to push cool air down. On cooler days, flip the switch on the center mount to the rotate the blades in a clockwise (or reverse) fashion, and set the fan on the lowest speed. The exception to this is for high volume ceilings, for which the speed needs to be at least medium. This creates an updraft and forces any warm air near the ceiling down into the room. Better yet, in our climate, cooler days are the perfect time to open those windows and enjoy our South Florida breeze.
 
 NREL National Renewable Energy Laboratory  Learn how to create a cross breeze.

We all know to open doors and windows that are opposite of each other to create cooling cross breezes. It is also possible to build this type of ventilation into a building. This informative brochure from the Department of Energy’s National Renewable Energy Laboratory provides details on combining fans with natural ventilation techniques. And, do not forget that your HVAC unit has a fan feature that can be used without the cooling compressor. When you do first decide to shut off the HVAC for the season and enjoy the winter breeze, take the opportunity to air out your system by switching your thermostat fan from the “auto” to “on” position for just a few hours.
 

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