Humans are creatures of comfort; and the story of civilization is, to a certain extent, the quest to keep from being either too hot or too cold. Considering the recent swings in temperature we’ve experienced, it could be considered the story of Saskatchewan, too.
The earliest form of climate control was the fire. Room temperature was controlled by adding more wood or coal to the fire or letting it die down. You fine-tuned your comfort by moving closer to or further from the blaze.
If you have an oil or gas furnace, your home today is still heated by combustion, but you don’t have to burn the fuel in your living room; instead, heated air is blown around the house by a fan. In another form of heating, the radiant system, hot water, air or steam is circulated through radiators, pipes or ducts hidden in the floor, ceiling or walls, or else electrical resistance heats wires in the walls (think of a giant toaster).
Finally, solar heating uses the energy of the sun, either letting it pour through big glass windows or soaking it up with a dark surface, under which run water pipes, providing hot water which can then be used for radiant heating.
Keeping warm is our primary concern in Saskatchewan, but come summer–and summer, is, finally, coming–our thoughts turn to keeping cool. The first attempts to cool rooms, in the 19th century, involved circulating air over blocks of ice. Mechanical refrigeration allowed more sophisticated methods, and although in 1748 William Cullen of the University of Glasgow demonstrated refrigeration, it was 86 years before Jacob Perkins patented the first practical ice-making machine in London and 1911 before Willis Carrier invented a practical air conditioning system in the U.S.
In both a refrigerator and an air conditioner, a liquid is boiled in an evaporator, absorbing heat as it expands. The warmed vapor is then compressed, which makes it even hotter (you’re packing the same amount of energy into a smaller space), and piped outside, where it radiates that heat away.
Today, you can hardly find a large building that isn’t heated and air conditioned to perfection under the careful control of computers programmed to ensure maximum efficiency and comfort.
Nevertheless, the quest for comfort continues, and now researchers in China may have come up with a whole new angle: paint that keeps homes warm in winter and cool in summer–and even changes colors with the seasons.
Developed by Yiping Ma and colleagues at Tongji University in Shanghai, the paint absorbs heat from the atmosphere when the temperature drops to below 20 degrees Celsius; when the temperature rises above 20 degrees, the paint automatically starts to reflect sunlight instead, keeping the building cooler. Tests have shown the paint can increase the internal temperature by four degrees in winter, and decrease it by eight degrees in summer–enough to have a substantial impact on heating and cooling bills.
The paint incorporates a “thermochromic substance,” a substance that changes colors as the temperature changes. Most thermochromic substances change colors at too high a temperature to be of any use, but Ma found that something called crystal violet lactone produces a variety of hues, from red to green to blue, at around room temperature.
To make his energy-saving paint, Ma incapsulated crystal violet lactone in a transparent polymer, then stirred it into regular wall paint. He figures its currently durable enough to last about four years; he’d like to increase that.
Ma thinks the paint can be formulated to color houses blue and green and other cool shades in the summer, and red and orange and other warm shades in the winter. (Of course, the ideal from a heating and cooling point of view would be paint that turns black in the winter and white in the summer, but researchers don’t figure that black houses in the winter would be very popular.)
Ma’s ultimate goal is a coating so effective that houses wouldn’t have to consume any fossil fuel–at least, not in China’s climate. (Whether any coating could deal that completely with Saskatchewan’s extremes is questionable.)
Despite all this scientific work on keeping the interiors of houses comfortable, however, one question remains to be answered.
How come, in any room containing two people (say, a husband and wife, to use an example chosen, I assure you, entirely at random) one is always too hot and the other too cold?
