There are a lot of stupid things spinning around, particularly on the internet.
Nonsense spins round right round like a record
On the energy side, one piece of advice that always annoys me is to ‘reverse your ceiling fan in winter’ because it is supposed to circulate the warm air back to you faster, or something like that.
That piece of nonsense and many others have been debunked by Massachusetts’ own Michael Blasnik, an efficiency expert with a penchant for actual statistics rather than feel-good ideas. If you ever have a chance to see him speak, take it – he’s fun, funny, engaging and a brilliant repository of energy information.
Some of you may have already seen his list of energy myths (pdf), which is summarized quite well by Green Building Advisor’s Martin Holladay here.
Despite a lack of data I still disagree with at least one of Blasnik’s myths (putting a lid on a pot of boiling water simply makes sense to me) but instead let’s focus on a few of the things he says you should do, that don’t require hiring anybody:
- Lower your thermostat setting.
- Set back the thermostat when you’re not home.
- Unplug second refrigerators and freezers.
- Make sure your furnace blower isn’t on all the time. (It should be set to “auto,” not “on.”)
On orchards in the springtime, large fans are used to turbulently mix warm air from above down to the surface. This helps protect the young fruit from frost damage on very cold nights.
The physics of this in the out-of-doors is that at night the earth surface temperature cools faster than the air, so that you have a very cool layer near the ground with warmer layers above. This is a stable condition, and the layers will not mix unless you mechanically force them to….thus the need for a fan. The fan creates turbulent convective cells which bring the warmer air down towards the surface.
Perhaps this same physics applies indoors in a very tall room with a cool layer of air near the floor and warm air above. The effectiveness of a ceiling fan might depend a lot on how the room is heated…forced air might be more self-mixing than radiative…just a guess though.
Painter’s plastic is amazing. It really works. i do it every winter. I also just made a box for a built in air conditioner unit. i uses 1″ polyisocyanurate (foam board with aluminum backing) and cut very straight lines using a sheet rock square. i then taped the edges with aluminum tape and it fit snugly over the AC unit. What a difference! The room is now one of the warmest in the house and it used to be the coldest.
I just did some work at the Shiloh Baptist Church (with Jeremy). The Deacon told me that he puts the ceiling fans on in the big room ( where the services are held) right before the service and it sends the warm air down to the worshipers. The ceilings are about 30 ft high. He swears it helps so perhaps it makes a difference if the room is really tall. Or perhaps he just imagines it helps. I know air movement usually makes a person feel cooler. Does anyone else feel they have experienced times when the fans pushing warm air down helped? Or seemed to have helped?
Jason the Energy Zealot
Great article. However, I’m a renter and I can’t make structural changes to the place where I live. Is there anything I can do to make the house warmer that doesn’t involve installing insulation and new windows?
Thanks Sarah, and yes, there are definitely things you can do to make the house warmer (even more to make the house more efficient.)
The easiest is to stop drafts on the windows using what I and others frequently call “renter’s plastic.” This is the material you put on windows with double-stick tape and then use a blow-dryer to ‘shrink wrap’ it. In the late spring/early summer you pull it off and it looks like it was never there. You can get it at any hardware store, and often free through freecycle or Craigslist.
Or, if you prefer, you can use “rope caulk,” also found at most hardware stores, to seal the windows. This is glorified silly putty that you apply around your windows to seal drafts. Also very inexpensive.
Before you leave in the morning, open all the window shades. In fact, you can leave them open all winter long because closing curtains doesn’t do much to save energy.
If you have windows in areas you seldom visit, such as a basement, you might consider cutting rigid insulation to size and keeping in place with tape or another means.
On the energy-savings, but not necessarily making the house warmer, side there are things like swapping out bulbs (take ’em with you when you leave!), programming your thermostat (or just turning it down/up at the appropriate times), etc.
Readers have other suggestions?