BACKGROUND: Hackensack University Medical Center is using recycled denim jeans to insulate their environmentally friendly hospital. Cotton insulation from these pre-consumer recycled jeans eliminates asbestos and formaldehyde, reducing irritation to the skin, nose and throat. Jean insulation holds more heat, and also absorbs more sound.
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 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.
MATERIAL FACTS: Less dense materials are better insulators. That's because in really dense materials, the atoms are closer together and can transfer energy back and forth much more easily. So gases insulate better than liquids, which in turn insulate better than solids. Those materials that don't conduct electricity well, such as wood, are also poor heat conductors, such as metals like copper.
DENIM INSULATION: UltraTouch cotton fiber insulation is made from recycled denim and cotton fibers, materials that act as insulators because of the looser structure, or "breathability,"of the fabric compared to tighter weaves. Denim dates back to 17th century France, when a type of wool-and-silk-based fabric called "serge de Nimes" was popular. Also popular was a cotton-linen-and-wool blend known as "jean." By the 19th century, denim had become the fabric of choice for sturdy work clothes, particularly in the West. Levi Strauss began manufacturing his version of "jeans" in 1873.