1) I have found no simple, dependable way of reclaiming heat from the dryer (i.e., re-condensing the moisture from its exhaust air);
2) Air-drying indoors in the winter is not much more energy-efficient (it uses almost as much heat as it saves) and not practical in the Cold House (things take eons to dry at our temperature, and we already have more than enough moisture in our air); and
3) Air-drying outdoors is fine in summer, but just not functional here in winter (clothes freeze before they dry, no one wants to wade through snow drifts to get to the laundry, etc.)
Now as the days get colder, I’m particularly displeased with running the dryer: I’ve done some math, and determined that in 45 minutes of running, the dryer sucks all the air from our cellar (which is replaced, of course, with cold air from outside.)
Frustrated with efforts to get back heat from the dryer, I turned my attention to the idea of using it less. One option was to not do laundry till spring: this was quickly squelched by J. The next option was extracting water mechanically rather than thermally. The idea there is that moving water uses much less energy than evaporating it.
I first tried giving laundry an extra run through the “spin” cycle of the washer, but that had no measurable effect. So, I made in investment in a commercial product, the hyper-drive spin-dryer from Laundry Alternative ($135). Success! Running a recent medium load of just-washed mixed clothing through the spinner, I extracted an extra 1.5 liters of water that would otherwise have been boiled off in the dryer. Based on some previous measurements, that represents about half the water content of the laundry load– which should, at least theoretically, reducing the dryer time by 50% (we do have a dryer that senses humidity and shuts itself off at a certain “dryness”, so there’s no guessing with a timer.)
Putting some real numbers to all this: the spin dryer uses 300 watts, and I ran it for about six minutes for this load of laundry– so that’s 0.03 KWh of electricity used. Compare this to the energy needed turn the same volume of water to steam: 0.95 KWh (and that’s assuming absolute efficiency– in reality of running the dryer, it would be more.) In other words, getting this 1.5L of water out with the spinner saves at least 97% of the electricity that the dryer would use to do the same job. Oh, and as an added (trivial) bonus: the 0.03 KWh it does consume winds up as heat inside the house, rather than sent outdoors!
The downsides to the spinner: (1) it isn’t dirt-cheap– at current electricity rates, it will take several years to actually pay for itself. Then again, our big dryer may last twice as long and need half as many repairs if we run it half as much, so you have to figure that in… (2) It’s a bit of a hassle– the spinner basket only hold a third what the washing machine does, so you need to spin a load in two or three stages. (3) The instructions have an inaccurate diagram which resulted in damage to the first unit I bought, having to return it, etc– if you actually buy one, email me and I’ll tell you how to avoid making the same mistake!