Five Percent: Conserve Energy

Climate Change Is Important: Energy Conservation is the First Step


April 22, 2006

Air Conditioner Alternatives

Category: Conservation,Household,Save Electricity,Take Actions,Tips – Tom Harrison – 4:29 pm

It’s not quite summer here in the Boston Area, but soon it will be hot, so this is a good time to get prepared for summer heat. Air conditioning is pretty much bad news from an energy standpoint. But I’m not going to try to say you shouldn’t use one. If I did, I would be a hypocrite, for one. But there are definitely some important steps you can take to reduce your use of A/C. Rather than starting with the obvious ones, here are some steps we have taken in our house that are not just alternatives, but which we much prefer.

Ceiling Fans

Ceiling fans are quiet and very, very effective. We got one from Casablanca, and also the Home Depot house brand, Hampton Bay. I much prefer the Casablanca (but that’s only partly because then tend to be higher quality; I have a general dislike of Home Depot). A typical model can be run at three speeds and usually have a pull-chain switch to adjust. Especially in a bedroom, it’s really nice to be able to control the fan from the bed, so it’s very nice to have a fan-control switch reachable from the bed. Some models now have remote controls that work similarly to a TV remote, and that seems pretty cool since no special wiring is needed, except if you’re like me, remote controls tend to be hard to find. A fan model we had in our old condo was very fancy and would automatically adjust to a lower speed after a certain amount of time — this is good because it tends to be hot when you go to bed, but cools during the night. This fancy model also had seven different speeds, I think, and it was indeed nice to be able to finely control the speed.

What is especially great about ceiling fans, aside from the fact that they use much, much less electricity and are much, much quieter is that they provide very pleasant cooling. Compared to window box fans and table or floor fans, they are much, much nicer. A very slight breeze is all you need.

We have ceiling fans in our bedroom and kitchen, and are getting them installed in the kids’ rooms.

Attic Exhaust Fans

If you live in a house with an attic, you can get a fan that mounts in the window of the gable, and is thermostatically controlled. Even if your attic floor is insulated, this makes a huge difference. As a side benefit, an attic exhaust fan will extend the life of your roof. Make sure to get a quiet one — we got the junky model the home store had, and it’s frame is so wobbly that the thing makes a lot more noise than it should and since it’s mounted to the frame of the house, the sound carries.

Whole-House Fans

A whole house fan is an amazing and wonderful thing. Through a hole in the top floor of the house, a large-diameter fan sucks air through the house through open windows on the first floor. You can cool the whole house in about 10 minutes! By selectively opening windows, you can get a nice draft in whatever rooms you want, but almost silently, and much more effectively than a box fan — this is great when you’re watching TV or cooking. If your house has a basement, you can open basement windows; the coolness of the ground will bring the coolest air into the house. You do have to have a nice smelling basement for this to be a good idea, however :-)

When you turn on the fan, louvers over the hole in the ceiling tilt up and let air through; when the fan’s off, gravity lets the louvers fall flat and they blend in to the ceiling.

Installing a whole house fan is a non-trivial effort. Because they are usually 32 inches in diameter, you’ll need to cut one of the ceiling joists in order to make room, and this is a job for a qualified carpenter. But this is an investment in your house — it’s really worth it.

A couple things to watch out for… First, get a belt-drive model; in these the motor is mounted on rubber bushings so that its vibration is not carried throughout the structure of the house — direct drive models will be noisier. Second, get a high-quality one — we got what they had at the home store, and the louvers are cheaply made, so rattle a little when it’s on, although this might also have to do with the installation; if there’s inadequate air flow out of the attic I think this can create a back-pressure that results in a rattle. One house I saw had a setup where the fan was actually mounted away from the hole in the ceiling, closer to the window — this was a really great and nearly silent setup.

Some Other Things To Consider

  • Don’t leave air conditioners running during the day, modern ones have timers and “Smart Set” energy saving options
  • Keep blinds and shades drawn during the day
  • Use the grill for cooking to keep the heat outside
  • Make sure your office HVAC system is set to cool at appropriate times, and not too cold
  • Turn out the lights, and avoid using incandescent lights when you do since they give off a lot of heat
  • Take a cold shower
  • Go to a movie on really hot days. But bring a sweater.

3 Comments

  1. Any recommendations or types of fans to avoid for Attic Exhaust Fans? Unlike consumer electronics, there don’t seem to be a lot of reviews or subjective or even objective details on attic exhaust fans. I’m getting one installed, but can’t seem to find out if the one my contractor has sucks or will be fine. The one I have is the Air Vent Inc #97669 PowerCool 1170CFM.

    I called Air Vent Inc at 800-AIR-VENT and a nice gentleman told me he had no idea how loud or quiet or vibration-free ANY of their products were. He was very nice about it, but was fully unhelpful in determining if any of their products were loud, quiet, or built to be vibration-free. Their website was equally unhelpful on that front. Since this will be installed above my bedroom and office, and I work from home, minimizing environmental noise is important to me.

    Comment by ooglek — April 21, 2009 @ 2:34 pm

  2. Interesting article about why not to use a powered attic ventilator, thought I’m not 100% sold on the tradeoffs.

    http://www.askthebuilder.com/236_Powered_Attic_Fans_-_Attic_Insulation_Facts.shtml

    Comment by ooglek — April 21, 2009 @ 2:39 pm

  3. Hi ooglek —

    We have a thermostatically controlled attic exhaust fan (which I should distinguish from our whole-house fan). It was whatever was available from Home Depot. I installed it in the larger of the gable-end windows in our attic — it turns on when it gets above 100 degrees or so.

    I really cannot gauge how effective it is, but my gut says it’s a good bet. The article you mention raises several good points: you certainly don’t want to suck air conditioned air out of your house. I think there are two keys for avoiding sucking air from your house.

    First, ensure that your attic floor is insulated well but also there are no gaping holes between the living space and the attic (the attic door would be a big possibility).

    Second when you install a vent, especially one that actively sucks hot air out, make sure there are sufficient intake vents (or open windows in the gable) so that air comes from outside. Most new roofs are installed with vents along the ridge cap, and you can install soffit vents, as well.

    The bottom line here is that as long as you are doing the right thing, getting cooler air from outside into the attic is a good thing. I live in Boston, but still, in the summer, it gets really, really hot up there when it’s all closed up. Clearing that heat from the attic is certainly a good thing.

    Hope this helps,

    Tom

    Comment by Tom Harrison — April 21, 2009 @ 4:42 pm

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