HOW INSULATION WORKS: Heat only flows in one direction: from a hotter object to a colder one, such as when your morning cup of coffee cools until it is the same temperature as your kitchen. Insulation serves as a barrier to minimize the transfer of heat from one material (the coffee) to another (the air around it). For example, pouring your coffee into a thermos made of an insulating material will prevent heat from escaping. Your coffee will stay hotter longer. Heat is transferred primarily through conduction, which occurs when materials directly contact each other. The atoms and molecules bump into those of the neighboring material, allowing energy to flow between them. Heat can also be transferred through convection. This happens with the flow of air and water. These substances don't readily conduct heat, but they can transfer heat energy through motion. Finally, hot objects emit infrared light, which can cause them to lose heat by transferring that energy to other objects -- heating up those objects in the process.
HOW CAN HOMES CONSERVE ENERGY? There are many ways in which houses can conserve energy. Improvements in energy-efficient lighting can reduce power usage by as much as 65 percent. In fact, if every American household changed just five of the most-used lighting fixtures to energy-efficient technology, they would save a total of $6 billion in costs and reduce power usage by the equivalent of the annual output of more than 21 power plants. Many homes have high-performance, energy-efficient windows -- featuring double glazing or special coatings -- to reduce heat loss in cooler climates and heat gain in warmer climates. These two factors account for 50 percent of a home's heating and cooling needs. Replacing window frames with low-conductance materials like wood, vinyl and fiberglass can also improve a home's insulating capability.
The Institute of Electrical and Electronics Engineers, Inc.-USA, the Optical Society of America and the American Physical Society contributed to the information contained in the TV portion of this report.