I can be a strange and particular person at times. So here is a post wherein I will be strangely particular about setting the temperature on your thermostat.
You often hear about how you should turn down the thermostat to save energy, and there are a slew of helpful ideas on the subject. I'm sure you've heard some of them right here on this blog: You can turn the thermostat down when you're out, when you're sleeping, and you can save about 1% on your energy bill per degree you turn your thermostat down! This is all very exciting.
But before you go crazy with turning down the thermostat really low, I'd like to point out some things you might want to keep in mind.
But first I have a story! Once upon a time, I knew someone who wanted to save money on her energy bill. And she was in a very drafty old place that got almost no sunlight and leaked air from every single crevice, so she was spending oodles on heating. So she decided to save money on heating! And she turned her heating off. Like, completely off. As far as I know, she went through every year I knew her without any heat at all on in her house. Goodness, she may very well be still doing it today.
Thankfully, she lives in the Pacific Northwest, where this is not that crazy an idea. But she can't be the only person out there who thought of this, so I'd like to remind you all out there: Please, save energy! Saving energy is good. But please, please think of your pipes before you go too crazy with the idea.
Frozen pipes are a big deal. If the water in your pipes starts freezing, you run the risk of that pipe exploding—and goodness knows that's not what most people are hoping to do when they're trying to save energy in the dead of winter. Unfortunately, I can't just say "keep your thermostat over X degrees to avoid pipe freezing." It depends on where you live, where your pipes are, and how well insulated those pipes are.
There are relatively few places in the United States where you'd never have to worry about frozen pipes. According to Weather.com, southern states generally start having issues with frozen pipes when the temperature reaches about 20 degrees Fahrenheit (the distinction is made because houses in the south are less likely to build pipes inside or in the "warm" parts of your home.) EERE's own Federal Energy Management Program has a file that shows the probability of frozen pipes in your region (PDF 115 KB). Download Adobe Reader.
So, unless you live in a place where it never gets below freezing (you lucky souls, you), you'll need to know some things about your house or apartment: Some water pipes will be in the "warm" parts of your house. This is why you don't want the temperature inside your house to drop too low, because bathroom and kitchen pipes are generally not insulated, and they rely on whatever system you're using to heat the rest of your house to keep warm.
And if you rent, you might want to see if the owners require their tenants to keep their thermostat above a certain level—my apartment requires all tenants to keep their thermostats above 65, for example, and asks us to consider leaving the taps dripping.
But while these are all good reasons to be careful with the temperature you keep your thermostat at, don't forget the rest of your pipes—some of your water pipes may be in "cold" parts of your house, like crawl spaces or attics, where they don't get any of your home's ambient heat and may, in fact, be subjected to air directly from the outside. What you'll need to do is based on the region you live in, so you may want to look up your state or city's Web site and see if they have recommendations on how to prepare your house for the winter, because you may want to insulate those pipes.
And, lest I forget to bring up something from the renewable energy field, you should also know that you need to take special precautions to make sure your solar water heaters don't freeze if you live in a cold enough climate.
In the end, I suppose it's still a judgment call, but just remember: Your pipes are vulnerable, frozen pipes are a pain, and you should always consider how your house is built before you make any drastic decisions on how to heat your home in the winter.