| While I hadn't given it much thought, it appears that when the temperature of the air outside and inside the house is quite different, using the dryer gives one a double whammy. Not only does it use a lot of energy to dry the materials, it uses air from inside the house to do the drying, then pushes it outside. Which requires bringing an equal volume of air, of a quite different temperature, into the house. Which gives your furnace/heating system, or air conditioner, quite a lot of extra work. Which uses more precious energy. And adds to global warming. Which is a major reason that I hang clothing outside on a clothesline through spring, summer and fall, and even on mild days in winter. Free drying. And have some lines in the basement that I use to dry a portion of the clothing, etc. in winter. Not quite free drying - about about the closest to it that's available. When I was in the townhouse in the city, we had a damper in the dryer vent that allowed us to vent the dryer into the basement. I usually vented a load or two per wash into the basement, as humid air requires less heating, and is better for furniture, plants, etc. There was a pair of pantyhose fastened over the end of the vent pipe, to collect lint, and it needed to be cleared occasionally ... and washed, to clear the lint from the gaps in the mesh.
In this area, a number of furnace installations include a stovepipe leading from the combustion area of the furnace to the outside, to pull in cold outside air to feed the fire, rather than using heated household air, then pushing it up the chimney to the outside. If one vented too much moisture into the house, one could develop problems with mould. I used to sell corn-fired heaters. They used about a bushel or slightly more of corn to heat a moderate sized house in a day, but pushed large volumes of air through the (small) fire, which meant that our installations always included a pipe to bring in outside air for that purpose, or we'd have been using a substantial portion of the recently heated air to feed the fire, then being blown outside. Reducing the efficiency of the heater very substantially. As it was, we claimed that those units provided the cheapest heat in town (except for wood that you cut yourself). It would scarcely be fair of us to claim that hundreds of millions of Chinese, Indians and others shouldn't use energy to provide more heat for warmer houses, operate fridges and TVs, and run cars ... when we've claimed such privileges for ourselves for most of a century. And global warming is a serious problem as things are at present. And pollution kills thousands of us annually. Big problems ahead ... not only in terms of energy supply ... but also in terms of the results of burning fossil fuels, etc. Have a great spring/summer week, everyone. ole joyful | 
