Energy

The ability to heat and cool is one important accomplishment of modern technology. Our ovens, freezers, and homes can be kept at any temperature we choose, a luxury that wasn't possible 100 years ago. But keeping our homes comfortable uses a lot of energy.

Lighting is also essential to a modern society. Lights have revolutionized the way we live, work, and play. Most homes still use the traditional incandescent bulbs invented by Thomas Edison. These bulbs convert only about 10% of the electricity they use into light; the other 90% is converted into heat. In 1879, the average bulb produced only 14 lumens (a measure of the quantity of light) per watt, compared to about 17 lumens per watt from modern incandescent bulbs. By adding halogen gases, the efficiency can be increased to 20 lumens per watt.

Compact fluorescent bulbs, or "CFLs," have made inroads into home lighting systems in the last few years. These bulbs last much longer and use much less energy than incandescent bulbs, producing significant savings over the life of the bulb.

Appliances such as refrigerators, washing machines, and dryers are also more energy efficient than they used to be. Congress passed the National Appliance Energy Conservation Act in 1990 that requires new appliances to meet strict energy efficiency standards. Learn what it means to be energy efficient.