Q My husband likes to leave fans on all day to cool the house even when we're not here. I say it's a waste of energy. Who's right?
A Nothing like a good green spat to fire up your love life or cool it down, depending on how ugly it gets. But, hey, at least you're arguing over fans, not air conditioners! Even though we're heading into a crisper season when fans tend to get tucked away, it's important to assess how we fared this summer.
The human body has a few ways of cooling down: one involves moving into a frigid space (duh), another is sweating (ick), and lastly there's wind power. I don't mean strapping a turbine to your roof to power your AC; I mean switching on a regular old fan and letting air blow across your skin.
One of the biggest energy-saving myths out there has to do with these machines, and I'm afraid your husband has fallen for it. The cooling power of a rotating blade is limited to the ability of that wind to reach human skin. If there's no one in the room, no one there to feel the breeze, you're just wasting energy. Literally.
Now, there are exceptions. One involves my dad's technique of positioning a fan at the bottom of the basement stairs and blowing cool air upwards to the higher floors . (Remember grade school science? Heat rises, so this trick actually works quite well).
If you have one room that's got a window AC unit, you'd also be smart to set up a fan system that pushes the air from that room to other parts of your house.
Even window fans that create good cross-ventilation (you adjust them to suck air in through one window and blow air out another to create a nice draft) will only help cool you at high noon on a blazing day with that wind-to-skin effect i.e., if there's a body to feel the breeze. It's when the outside air is cooler than the inside air (like, say, when the sun starts to set) that these babies can really help usher in cooler temps in a hurry.
Still more effective at the "bring the cool morning or night air in and push the stale sticky inside air out" thing is the whole-house fan . These aren't as popular in Canada as they are in the U.S., but they're awesome at pulling cooler air from lower levels into upper floors and shoving hot, sticky air out of the attic.
And just because winter is coming (there, I said it) doesn't mean you won't get use out of your fan. Ceiling fans in particular can be great at pushing heat that's risen up to the ceiling back down where you can feel it. Just make sure you reverse your fan's direction when your furnace kicks in.
Oh, and for those out there using area fans along with your central AC, you want to make sure to raise your AC by a degree or two . Otherwise, your fans are just adding to your power load.
But back to your battle on the home front. You can tell your husband that you're right and he's wrong.
And for the rest of you, now's a great time to assess your summer's eco footprint . Pull out your hydro bills and see whether you managed to use less dirty electricity than last year. Did you try using pedal power over metal power ? If you drove to a cottage, did you at least carpool ? Any great ideas on how to shrink your big feet down for next summer? You still have three official weeks of the season to get your butt in gear.