Lazy Line Dry

Step 9 Technical notes: effect of inside line-drying on heating and air conditioning

In hot, dry conditions, hanging clothes inside will help cool the space by evaporative cooling, and will be beneficial whether you
have air conditioning or not.

In hot, humid conditions, the evaporative cooling will still happen, but the added humidity may make the air overall slightly more uncomfortable, so it's better to hang the clothes outside. But the two effects partly cancel, so it's still OK to hang clothes inside if that's most convenient.

In the winter, many houses are overly dry inside, and the added humidification can be helpful. The small evaporative cooling effect will need to be overcome by the heating system, but, unless you have electric heat, this is reasonably efficient and much better than running an electric humidifier, and that's before even considering the energy savings from avoiding using the dryer.

If your house is very dry in the winter, this may be an indication that there are air leaks in the building envelope or ducts. If you get it sealed well enough that humidity gets higher than you'd like, it may be time to consider installing a heat-recovery ventilator. That will allow bringing in fresh, dry air and exhausting stale, damp air, without losing the heat in it.

In summary, drying clothes indoors can be beneficial to the indoor climate if it's dry inside, in either winter or summer. If it's humid inside, it would be better to dry the clothes outside, but it's still a lot better to line-dry them inside than to use a dryer.

Comments

[hlubinka]

I wonder if it is more efficient to hang dry clothes inside the house, vs using a dryer. (not just if it helps with the humidity.)

I have an ongoing disagreement with a friend about whether it is more efficient to use my gas dryer to dry a load of laundry or to hang dry the clothes inside, in a big house which uses gas heat. I feel hang drying takes advantage of the ambient heat and dry air of the wintry months, when it's raining and I can't hang dry my clothes outside. He always contends that the dryer is an appliance designed to dry clothes, so it must be more efficient, and that hang drying would cost more kWh of energy in the end, because the whole house gets colder and has to be heated more.

Any idea how one could actually measure the efficiencies of each approach?

[LowEnergy]

Good question.  Here's an idea for something to measure.  Measure the temperature of the air coming out of the dryer vent.  The energy from burning gas in the dryer goes to two things: evaporating the moisture in the clothes, and heating the air.  If all the energy went into evaporating the moisture (what you'd want for high efficiency), the air would exit at room temperature.  How much higher the temperature is gives you a measure of how much energy was wasted.  To really figure out how much energy was wasted you'd need to also measure the airflow rate, but you can get a feel for it just from the temperature.  If it's just a few degrees warmer than room temperature, the dryer's pretty efficiency, but if it's significantly warmer, that's all energy going to waste. 

(Actually, if it's cold outside, even if the air exiting the dryer is at room temperature, it's wasting a bunch of energy, because for each cubic foot of air blown out the vent, there's a cubic foot of air sucked into the building from outside, which has to be heated by the heating system.)

On the other hand, with the clothes hung inside, the only extra heat you need is exactly the amount of heat needed to evaporate the water--that's how much the building is cooled by having them drying inside.

[hlubinka]

Thanks -- that's very helpful. I forgot to include that another one of my arguments against the dryer is that one also spends electricity on tumbling the clothes around by turning the cylinder with a motor for about 40 minutes. I gather from your comment that one would guess that hang-drying in the home is usually more efficient than tumble-drying.

Since you have provided a really thoughtful answer, I wonder if you can imagine a scenario in which it would be less efficient to hang-dry one's clothes. And someday when I get a chance I'll try measuring the temperature as you suggest so we can have hard proof!

[belcat]

Somehow I find it hard to believe your mother (or whoever does the laundry) would object to you doing your own laundry, and hanging it on some indoor laundry thing. Or some string strung up somewhere.

[i_was_like_you]

Good response. I've been doing my own laundry for quite some time. There are bachelors (and bachelorettes) and then there are bachelors. That is, there are those of us who have had to do things on our own even when we lived at home and so transitioning to having to do them in our entire living space isn't quite the jump. Keeping in theme with this "lazy" guide, less is so much more. Why have to clean when we can avoid making a mess. Yeah, I should probably do certain types of cleaning more often, but overall, avoiding making the mess is lazier than having a mess to clean up. I've had friends who so many easy tasks just seem to be out of their grasp. Cooking something that didn't have clear microwave instructions and packaging eludes them. Separating laundry into reasonable piles (as in whites and / or light colors, darks, and items that can and probably will bleed onto other clothes, which I usually just wash with the darks) also astounds them as does the idea of folding clothes while they are fresh out of the dryer (if one isn't hanging them to dry or after drying) cuts down on wrinkles. Even further, though, they lack basic automotive skills. I'll admit I was too busy playing to pay much attention to learning auto repair from my grandpa, but I can still get by, especially after watching someone do it once. I change my own brakes (on the front at least), oil (even though automakers need to find better places to mount the filters on some engines, namely the now discontinued Cavalier), sparkplugs and wires (again, automakers need to find better places to mount auxillary equipment so as to not block off access to the spark plugs). Other than problems that usually require professional equipment, those are some of the main things that a car needs serviced.

[Peacemaker636]

I wish my parents believed in indoor line-drying. We could save tons of money. But they don't, and we won't (but when I'm on my own I will do whatever I want :D )