Q.Dear Umbra,

What is the most cost-effective and environmentally friendly method to dehumidify a small apartment? It’s getting too cold to keep the windows open all the time and the condensation they’re accumulating might just be enough to stop California’s drought. I only have two windows and a small fan in the bathroom, which I leave on while I shower. I’ve heard that salt can be a good way of sucking moisture from the air — is this true? I’ve looked into the huge dehumidifiers and they just scare me: The energy they require is enormous, plus they’re loud and expensive. There are a few chemical options too, but I’m not sure if they’d work.

Chiara M.
Berlin

A. Dearest Chiara,

Dry winter air, with all its static-raising, skin-flaking effects, is no picnic. But for my money, it’s the humid cold that really gets you, giving your otherwise cozy home the ambiance of a damp medieval castle (now we know why the royals in those old portraits always look so miserable). Clammy winter air brings practical problems too: warped wood, peeling paint, and a higher risk for mold and mildew. It’s like a terrible, upside-down version of a sauna.

The bright side: You don’t have to resign yourself to dripping walls all winter, Chiara. But the best solution might well involve one of those not-so-frightening electric dehumidifiers. Let’s look a little more closely.

We have several tools to combat excess moisture in your apartment: venting, desiccants, and dehumidifiers. Venting — from opening the windows to flipping on an exhaust fan — shunts humid air directly outside. Desiccants, or substances that absorb dampness, yank water from the air and hold it. Electric dehumidifiers work by pulling wet air over refrigerated coils, which forces the water to condense and drip away. Sometimes a combination of these solutions will be the best solution, depending on your dwelling and your climate.

Venting is the simplest option, but not exactly the brightest idea come winter: Opening the windows will make you shiver, and then it will make your heating system crank up, which has its own energy costs. Your home exhaust fans do the same job without the blast of cold air, but you’ll still have to deal with the uptick in your heating bill. Still, I think judicious use of fans is okay in apartments with humidity problems: Try flipping on the bathroom and kitchen fans for 5 or 10 minutes after showering or boiling something on the stove to clear out the worst of the fog.

Then we have the chemical desiccants you asked about, Chiara. These come in both commercial and DIY varieties; some people swear by setting out pans of rock salt, silica kitty litter, charcoal, or calcium chloride (another type of salt, and one you need to be careful with) to reduce humidity. All evidence I could find of the effectiveness of these methods is anecdotal. You can certainly try them, but I suspect many work best for small spaces, like closets. An important note on calcium chloride: If you’re inclined to experiment with this one (frequently used as a deicer for roads and sidewalks), I’d stick with the packaged commercial version, which stores the salt and the brine (the resulting salty water) in a container, over an open pan of the stuff. Though it’s not exactly dangerous, calcium chloride can be irritating to the lungs and skin, and you definitely don’t want to swallow it (a matter of concern if you have young ones or pets around).

Dehumidifiers, on the other hand, definitely work — though you’ll pay a price both in upfront cost and electricity use. But if the other methods are leaving puddles on your windowsills, the machine might be your best bet. As always, smart shopping and smart usage will minimize the appliance’s impact: Look for an Energy Star-rated model (which saves you about 15 percent in energy use) that has a humidistat. Like a thermostat, a humidistat lets you set your desired humidity level and will keep the appliance from running endlessly. And you probably don’t need a huge unit, Chiara — check out this chart to estimate what capacity you need and buy the smallest one that will get the job done.

No matter which methods you choose, you should also think about how to cut down on the moisture creeping into your home in the first place. Some measures will require your landlord’s buy-in, such as making sure you have adequate drainage around your building’s foundation and properly routed gutters. But you can also take simple daily steps: Commit to shorter, cooler showers and skip bubbling pots on the stovetop in favor of slow-cooked or roasted meals.

I’m confident one or more of these tips will help keep your apartment feeling less like a bone-chillingly humid castle and more like a snug winter retreat. And if you want to collect the drippings from your energy-sipping dehumidifier and send them to California, I’m sure the good people there would be grateful.

Condensationally,
Umbra