What Are the Best Thermal Insulators?

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The best thermal insulators include aerogel, fiberglass, mineral wool, polystyrene, polyurethane foam and cellulose. Other effective insulators include cotton, straw and animal wool. Each material excels in separate applications and environments.

The most effective insulating material is aerogel, a compound that withstands temperatures up to 2,000 degrees Fahrenheit. Spacecraft insulation tiles are made with aerogel. Its primary drawback is its high cost.

Fiberglass is the most popular insulating material because it is affordable, durable and non-flammable. This material consists of microscopic glass threads woven together with tiny fibers. The negative aspect of fiberglass insulation is that it is dangerous to handle. Installation professionals must wear full-body protective suits with self-contained breathing systems to prevent skin, eye and respiratory tract irritation.

Mineral wool insulation resembles fiberglass but is not dangerous to handle. Its principal drawback is that most brands of mineral wool insulation are flammable. Consequently, it is not suitable for extremely hot environments or in areas that contain flammable chemicals.

Like fiberglass, polyurethane foam insulation requires professional installation. Once it dries, this material is an excellent insulator. It is not ecologically friendly, however, and contains many harsh chemicals. Individuals who prefer natural insulation materials often choose cellulose, which is non-flammable, contains recycled paper products and provides excellent heat retention.