COPYRIGHT 2018 JAMES DULLEY ( www.dulley.com/sea/ ) - July 2018 - (graphics ref. No. 402u at www.dulley.com/sea/column/2018-jul.htm ) "Tips for using indoor fans and fresh air ventilation to reduce air-conditioning and improve comfort" Dear Jim: We like to be cool, but our old air conditioner is expensive to run. Are there ways to use ventilation to stay comfortable without running it as much? - Michael A. Dear Michael: Proper ventilation, both from outdoors and within your house, can make you feel cooler and reduce your air-conditioning. The room air temperature in your home actually is not most important. The cooling sensation on your skin is. Human nature being what it is, people often incorrectly perceive comfort level by the temperature setting. Moving air feels many degrees cooler than still air at the same temperature allowing you to set the air-conditioner thermostat a few degrees higher. This is partially due to the fact the more heat is transferred from your skin to moving air. Also, as air flows over your skin, moisture evaporates even if you are not noticeably sweating and this feels cooler. There are two types of ventilation. One is moving indoor air throughout your house with the windows closed. In addition to making you feel cooler, it can balance out room temperatures and actually lower the temperature in some rooms and raise it in others. The other type of ventilation is bringing in outdoor air at times and shutting of the central air-conditioning. Both have their places and can be effective. Installing a ceiling paddle fan is what is commonly thought of as indoor ventilation and it does work well. Run the ceiling fan on medium or high speed with the air blowing down to create a direct breeze on your skin. During the winter, reverse the blade rotation and run it on low speed. This gently circulates the warm air around the room without creating a chilly breeze. Select the proper-size ceiling fan or you will just be wasting electricity and gaining little comfort. A sizing rule-of-thumb for a lower-cost four- or five-blade fan is (room size vs. diameter of blades): up to 75 sq. ft. - 36 in., 75 to 144 sq. ft. - 36 to 42 in., 144 to 225 sq. ft. - 44 to 50 in., 225 to 400 sq. ft. - 50 to 54 in. Although running any electric fan can make your feel cooler, it does not cool the room. It actually heats the room air because all of the electricity used ends up as heat. When no one is in a room to feel the cooling breeze, switch off any electric fan, including ceiling fans. Each kilowatt-hour of electricity used by a fan produces 3,414 Btu of heat which your central air-conditioner has to remove. Small personal fans can be very effective to create a breeze directly on you while you sit in a chair or work at one location. If you purchase a small fan, select one that can also be used as a zoning space heater during winter. The heating elements do not block much air flow in fan-only operation. Also, select a multi- or variable-speed fan with a wide range of speeds. A good rule of thumb is you should be able to feel a comfortable breeze at 10 feet away at high speed. You should feel just a slight air movement at three feet away at low speed. A horizontal reversible dual window fan provides an even wider range of ventilation options for comfort. Small personal fans are available. Vornado offers one with cage-less soft blades that will not harm your skin if you bump it. It is foldable for portability. Dewalt offers a variable-speed cordless fan with a rechargeable 20-volt lithium-ion battery. It can run for seven hours at maximum speed with 500 cfm (cubic feet per minute). Move it with you from room to room. Setting your air central air conditioner blower to "on" can help to balance out room temperatures, but it will not create much of a cooling breeze. Standard blower motors are powerful and running one continuously heats the air. Variable-speed ECM blower motors use less electricity on continuous low speed, so running these blower makes more sense. Natural outdoor ventilation is effective and free. An effective tip is when you open double-hung windows or an entry door with a storm/screen door, open both the top and bottom sashes a little. This creates a natural vertical air flow, even on a still day, which will mix with the indoor air. Sit near a window on the windward side and on the first floor if you have a two-story home. Open the window just a little. Open the windows much wider on the other side or on the second floor. This creates a higher velocity of the incoming air for a stronger breeze. The following companies offer air ventilation products: Dewalt, (800) 433-9258, www.dewalt.com; Holmes Products, (800) 546-5637, www.holmesproducts.com; Hunter, (888) 830-1326, www.hunterfan.com; Kaz, (800) 332-1110, www.kaz.com; and Vornado, (800) 234-0604, www.vornado.com. Dear Jim: My house has a little insulation in the attic, but it is under a plywood floor. I want to add much more insulation. Will the plywood floor under the new insulation cause a problem? - Bob J. Dear Bob: If the plywood covers the majority of the attic, it may act as a vapor barrier over the existing insulation. If you are installing heavy insulation over it, this should take care of a possible moisture condensation. It still would not hurt to drill some one-half-inch holes through the plywood. This provides some air circulation through it for any moisture vapor to escape. The moisture comes from the living area below. Send inquiries to James Dulley, Publication Name, 6906 Royalgreen Dr., Cincinnati, OH 45244 or visit www.dulley.com.