With a title like that, maybe you are thinking about European soccer matches? But what I am actually referring to is something equally violent with respect to the environment: the simple bathroom fan. It sucks. Or blows. Your choice. Either way, it’s not good.
What is the problem with bathroom fans?
Well, have you ever wondered where the air that it pumps goes? Usually, it goes directly to your attic, taking with it a valuable resource: its heat. There are many, many ways in which a house is inefficient with heat, causing you to spend a lot more money and produce a larger carbon footprint than you have to in order to get your house to the desired temperature. The bathroom fan is one of them.
In the winter, you spend a bunch of money on natural gas, heating oil, or electricity to heat up the air in your home to a comfortable level. Then, you go to the bathroom, and proceed to pump that nice warm air into the cold attic — ie. outside your insulation (if you have it) and effectively, outside your house!
In the summer, the same thing. You spend a lot of energy on air conditioning, and that nice cool air gets pumped right up into the attic, meaning you have to produce a bunch more air conditioned air to replace it in the rest of the house.
How wasteful is it?
Fans are rated by how much air they can pump in one minute as measured in cubic feet per minute (CFM). Many pump about 70 to 80 CFM, but some are powerful enough to pump 200 CFM. A typical home contains about 12,000 to 15,000 cubic feet of air. That means that little 100 CFM fan in the bathroom can pump out the entire volume of the house in about 120 to 150 minutes or so. Most of that air is replaced by outside air that needs to be heated up or cooled down as appropriate.
Now, we have all forgotten to turn off a bathroom fan for a few hours, right? We come back from that shopping trip 3 hours later and realize we left the bathroom fan on. Oh well, it can’t be that bad, we think. Well, the entire volume of the house has been replaced, and that means we have spent a deal deal of energy just heating the new air for nothing!
So what to do about these fans?
Well, what I have started doing is using the fan for one purpose and one purpose only — to evacuate the bathroom of uh… “undesirable odours” shall we say. When the undesirable air is gone, I turn the fan off immediately. In the spring or fall, if the outside air is a mild temperature, I just open the window and leave the fan off for this purpose too.
I do not turn on the fan for showers or baths or any other reason.
This has a number of advantages:
- The heat contained in the air from the shower water will migrate into the house instead of being pumped outside.
- In the winter or summer, the humidity generated by a shower will help to rehumidify the house air. Both furnaces and air conditioners tend to dry the air out (which is why some people get bloody noses in the winter or summer). You just have to make sure to leave the bathroom door open when you are done so that it dries out, otherwise you can start growing mold and mildew. Our bathroom usually dries out in about 20 minutes with just the door open. Humid air also retains heat better than dry air, so it will help [very slightly] reduce your cooling or heating costs as well.
- The moisture in the air that is pumped up to the attic with the bathroom fan will condense when it hits the cooler air in the attic. Cold and damp is perfect conditions for growing fungus, mold, and mildew. If the mold gets completely out of control in your attic, it can create very serious health problems due to the toxins they can contain.
- I can’t forget to turn off the fan, because it is already off.
- A regular bathroom fan uses 40 to 75 watts or so. That is equivalent to a small incandescent light bulb. By not turning on the fan, I am not using electricity to run it. Assuming I take one shower a day and the fan is running for 20 minutes (15 min shower + 5 minutes to dry out the bathroom afterwards), that comes to 5.9 kWh per year saved, which costs me about 77c around here. Not a big deal, but all these sort of little things can add up over time.
- Our orchids LOVE the warmth and humidity in the bathroom. Now they are actually starting to bloom.
- In the winter, the bathroom stays warm when you are done showering, until you open the bathroom door to let it air out. This means you are not freezing before you get the chance to dry off. With the bathroom fan on, the warm, moist bathroom air is replaced by the cooler air from the rest of your house, making it unpleasant to step out of the shower.
- Best of all, this is something green I can do that costs nothing!