Ways to produce and save heat

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None of the methods in this column will solve all heating and cooling problems by themselves, but applying each when it's appropriate in season will contribute to our overall well being. All of these tips will apply when there's a need or a desire to turn off or minimize the use of furnaces and air conditioning units. One of the key concepts bearing on many of the techniques listed here is the idea of the thermal cell. Warm air rises and cool air sinks. Take a bottle of tea or water out of the fridge on a warm day and let it sit on the counter for an hour. Open it and sip out of the top, and keep drinking. The first sips are warmer than the ones after it because the warmest liquid rises to the top. The coldest part sinks to the bottom. Drink a hot cup of tea or coffee, and the warmest is always on the top. When the top is cool enough to sip, what is below it is even cooler.