PHASE-CHANGING MATERIAL: When the temperature (and/or pressure) rises or drops to the point at which materials change from a liquid to a gas or a solid to a liquid, that's called a phase change or transition. Water (H2O) is the most familiar example. It can be a solid (ice), a liquid (water), or a gas (steam), but it is still made up of molecules of H2O, so its chemical composition remains unchanged. At sea level, water freezes at 32 degrees Fahrenheit (0 degrees Celsius) and boils at 212 degrees Fahrenheit (100 degrees Celsius), but this behavior changes at different altitudes because the atmospheric pressure changes. In fact, get the pressure low enough and water will boil at room temperature. This phenomenon is used with a new type of roofing material, which allows much of the heat energy to go toward changing the phase of a material, which slows abrupt temperature changes.
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 you). For example, pouring your coffee into a thermos made of an insulating material will slow the rate of cooling and 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.
The Materials Research Society and the American Society of Civil Engineers,and the American Physical Society contributed to the information contained in the TV portion of this report.