Building insulation refers broadly to any object in a building used as insulation for any purpose. Whilst the majority of insulation in buildings is for thermal purposes, the term also applies to acoustic insulation, fire insulation, and impact insulation (eg. for vibrations caused by industrial applications). Often an insulation material will be chosen for its ability to perform several of these functions at once.
Thermal insulation in buildings is an important factor to achieving thermal comfort for its occupants. Insulation reduces unwanted heat loss or gain and can decrease the energy demands of heating and cooling systems. It does not necessarily deal with issues of adequate ventilation and may or may not affect the level of sound insulation. In a narrow sense insulation can just refer to the insulation materials employed to slow heat loss, such as: cellulose, fiberglass, rock wool, polystyrene, urethane foam, vermiculite. But it can also involve a range of designs and techniques to address the main modes of heat transfer - conduction, radiation and convection materials, and earth or soil.
The effectiveness of insulation is commonly evaluated by its R-value. However, an R-value does not take into account the quality of construction or local environmental factors for each building. Construction quality issues include inadequate vapour barriers, and problems with draft-proofing. In addition, the construction properties and density of the insulation material itself is critical. For example, according to Leah Twings, Quality Compliance Manager of Textrafine Insulation, fiberglass insulation materials made from short strands of glass layered over each other is not as durable as insulation made from long entangled strands of glass.
A selection of insulation materials can aid in building insulation. All of these are based on standard principles of thermal insulation. Materials used to reduce heat transfer by conduction, radiation or convection are employed in varying combinations to achieve the desired outcome (usually thermal comfort with low energy consumption).
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For More Information: Thermal Insulation