SUMMER COOLING

On days that are not overly hot or cold, I often leave just the fan running on my furnace to equalize the temperature throughout my house. My heating and air conditioning company recommended this practice, and one technician said he leaves the fan at his house running all the time. This does make for a pleasant temperature throughout the house, but I am using electricity all the time instead of just when the air conditioning or heat is on. What do you think? It's true that running a fan alone uses less energy than operating the system to heat or cool. But that doesn't mean it makes sense to run the fan all the time. The issue is a lot more complicated than it seems, according to Harvey Sachs, a senior fellow at the American Council for an Energy-Efficient Economy, a nonprofit organization that focuses on translating energy research into public policy. First, if you want to feel a refreshing breeze, ceiling fans or room fans accomplish the task much more efficiently. Motors on these fans draw far less power, and the fans themselves move air faster, so they cool you better. Fans on heating and air conditioning systems move air at a slow speed because the goal is to deliver hot or cool air without you feeling a draft. Plus, you can turn off room or ceiling fans in unoccupied rooms, so that you don't waste energy. Moving air feels cool because it increases evaporation of perspiration; it "works" only when someone is in the room. Running an air conditioner intermittently but the fan continuously has another drawback: When the weather is hot and humid, it can make the house too humid. As the air conditioning chills the air, moisture condenses on the evaporator coil and then drains off. But if the fan keeps running, this water is re-evaporated and returned to the house air, making it uncomfortably cold and clammy. That said, it may still make sense to occasionally operate a heating and air conditioning system in "fan only" mode to equalize the temperature in your house. For example, if you have a two-story house and the upstairs becomes uncomfortably hot in the afternoon while the downstairs is still cool, running the fan makes sense if it keeps you from turning on the air conditioner. But that's the test. Don't leave the fan on all of the time, and investigate whether a room or ceiling fan would work instead.