The invention Cox calls a "glorified oven mitt" fits around your single-pipe radiator and fixes the uncontrollable temperature swings most steam-heated units experience. Today, most new buildings are heated through forced hot air or hot water. But older buildings, especially those built before World War II, use steam heat, and in the 1970s, the rise of double-paned glass windows, which are excellent insulators, radically changed the amount of heat needed to keep a room warm -- and changed it by different amounts for each room -- causing those dramatic temperature swings. This is especially problematic in apartment buildings, where the boiler is all on, or all off, for everyone--there's no halfway with steam heat. So buildings have to cater their heat consumption to the coldest apartment in the unit, leaving residents in some apartments hot and bothered while other units feel comfortable. It isn't just unpleasant, it's bad for the environment: Up to 30 percent of the energy generated by steam heated radiators goes to waste. New York City, an area that uses 20 percent of the nation's steam heat, wastes hundreds of millions of dollars every winter keeping many of its residents uncomfortable.