Thermal insulation refers to materials used to reduce heat transfer (thermal transmittance) between objects in thermal contact or in thermal radiation exchange. The goal is to slow down heat flow to maintain different temperatures on either side of the material. Some common examples include fiberglass, rock wool, polystyrene foam, and polyurethane foam used in walls, attics, pipes, and other applications.

Fiberglass Insulation

Fiberglass insulation is one of the most widely used Thermal Insulation Materials. It is made from extremely fine glass fibers produced from drawn glass. The fibers have diameters around 3–13 micrometers and lengths of 3–6 mm. Fiberglass insulation takes advantage of the low thermal conductivity of glass and the high surface area of finely divided glass fibers to significantly impede heat flow. Typical bulk densities range from 0.5–4 lb/ft3.

Some key properties of fiberglass insulation include: density-dependent R-value between R-3 to R-3.7 per inch, melting point over 2000°F, water resistance, stability at high and low temperatures, low cost, and ease of installation. It is commonly used in walls, attics, basements, and other parts of buildings for its good performance and affordability. However, it can irritate skin and lungs during installation if proper protective gear is not worn.

Mineral Wool Insulation

Mineral wool insulation is manufactured by spinning or blowing slag or other materials to produce fibers. It includes rock wool and slag wool. Rock wool is produced from basalt rock and slag wool from blast furnace slag. Mineral wool has open porous structures which trap small pockets of air for improved insulation properties.
Its typical properties are R-value 2.5-4 per inch, melting point over 2000°F, resistance to fire, rot and moisture, and stability against shrinking, settling, and aging. Mineral wool insulation is used in commercial buildings for industrial piping and equipment, walls, roofs, and HVAC ducts due to its excellent fire resistance. One downside is that mineral wool fibers can cause itching if they contact skin. Proper handling is needed during and after installation.

Polystyrene Foam Board Insulation

Polystyrene foam board comes as rigid insulation sheets made of expanded polystyrene (EPS) or extruded polystyrene (XPS). It has closed cell structure which gives small spaces filled with air or other gases. Common brands are Styrofoam and Thermalite.

Key attributes are high R-values between R-3.8 to R-6.5 per inch, moisture resistance, lightweight, easy cutting, stability, and cost effectiveness. Applications include insulating foundations, crawl spaces, attics, walls, roofs, ductwork, pipes, tanks. It is commonly used outdoors and below grade due to moisture resistance. However, polystyrene is combustible and can release toxic gases if burned, so fire retardant versions are recommended for some applications.

Polyurethane and Polyisocyanurate Foam Insulation

Polyurethane foam is a spray-applied rigid plastic foam insulation. It reacts rápidly and expands up to 60 times its initial volume during application to completely fill cavities. Types are spray foam (open cell, closed cell) and poured foam boards. Typical properties are R-values 6.5-7 per inch, high resistánce to moisture and vapor, excellent adhesion to substrates, fills irregular shapes, and provides an airtight seal. It is more expensive than other foams but delivers high performance.

Some applications of polyurethane foam are exterior and interior walls, attics, foundations, tanks, ducts, pipes where a continuous insulation and air/vapor barrier is needed. Polyisocyanurate foam is similar to polyurethane but provides even higher fire resistance, making it well suited for roofing applications in commercial buildings. However, both materials require protection from UV exposure if left exposed. Precautions are also needed during application due to toxic fumes.

Other Common Thermal Insulation Materials

In addition to the materials discussed above, some other common thermal insulation types used in construction include:
Cellulose Insulation: Made from recycled paper, it provides good fire resistance and is cheaper than fiberglass. It is commonly used for walls, attics and other areas.
Perlite Insulation Board: Composed of volcanic ash that has been heat-expanded into a lightweight aggregate. It performs well as a thermal and acoustic insulator. Used in masonry block walls and poured concrete roof decks.
Aerogel Insulation: A synthetic porous ultralight material derived from silica gel or cellulose. It has extremely high insulation properties and low density but high cost limits current applications.
Reflective Insulation: Thin laminated foils or membrane radiant barriers that reflect infrared radiation to reduce heat transfer. Installed on attic floors, behind radiators or in building envelopes.
Natural Fiber Insulation: Insulation made from plants like wood fiber, cork, hemp, and cotton provide sustainability with good thermal performance. Used for walls, attics and pipe insulation.

The choice of thermal insulation material depends on the specific application, installation requirements, temperatures encountered, cost priorities, fire safety needs and other factors. Fiberglass, mineral wool, foam boards and spray foams cover a wide range of uses due to varying properties. Understanding these materials enables specifying the right product to achieve maximum energy efficiency through reduced heat transfer.

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