In a rare example of the government using words efficiently, the Department of Energy provides an excellent explanation of the role of insulation . Heat, DOE says, has a natural inclination to migrate to anywhere there is a cooler temperature. Therefore, in winter, heat wants out; out of heated living areas into the colder walls, basements, and if it can get there, outside. In the summer it wants in, sneaking through walls, cracks, and holes into the cooler air in or under a building. Therefore,...