The Energy Independence and Security Act of 2007 (EISA) mandates the phase-out of incandescent light bulbs, and favors energy-efficient compact fluorescent light (CFL) bulbs. Sounds good—until you realize that CFL bulbs contain mercury, and mercury poses a significant cancer risk. A new study shows that CFL bulbs also emit high levels of ultraviolet radiation—specifically, UVC and UVA rays. In fact, the UV rays are so strong that they can actually burn skin and skin cells. Ex

Geothermal heat pumps use the constant temperature of the earth as an exchange medium for heat. Although many parts of the country experience seasonal temperature extremes—from scorching heat in the summer to sub-zero cold in the winter—the ground a few feet below the earth's surface remains at a relatively constant temperature. Depending on the latitude, ground temperatures range from 45°F (7°C) to 75°F (21°C). So, like a cave's, the ground's temperature is warmer than the a