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Installed faced fiberglass batt insulation with its R-value visible (R-21) [1]. The R-value is a measure of how well a two-dimensional barrier, such as a layer of insulation, a window or a complete wall or ceiling, resists the conductive [2] flow of heat, in the context of construction. [3]
This is a list of insulation materials used around the world. Typical R-values are given for various materials and structures as approximations based on the average of available figures and are sorted by lowest value. R-value at 1 m gives R-values normalised to a 1 metre (3 ft 3 in) thickness and sorts by median value of the range.
This means that VIPs have about one-fifth the thermal conductivity of conventional insulation, and therefore about five times the thermal resistance per unit thickness. Based on a typical k-value of 0.007 W/(m·K), the R-value of a typical 25-millimetre-thick (1 in) VIP would be 3.5 m 2 ·K/W (20 h·ft 2 ·°F/BTU). To provide the same R-value ...
Pillar spacing and diameter limited the insulation achieved by designs available beginning in the 1990s to R = 4.7 h·°F·ft2/BTU (0.83 m2·K/W) no better than high quality double glazed insulated glass units. Recent products claim performance of R = 14 h·°F·ft2/BTU (2.5 m2·K/W) which exceeds triple glazed insulated glass units. [16]
R-Value 3.4 – 3.8 (RSI-0.60 – 0.67) per inch (imperial units) Loose fill insulation fills the wall cavity better than batts. Wet-spray applications typically seal even better than dry-spray.
The construction industry makes use of measures such as the R-value (resistance) and the U-value (transmittance or conductance). Although related to the thermal conductivity of a material used in an insulation product or assembly, R- and U-values are measured per unit area, and depend on the specified thickness of the product or assembly. [note 2]
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Passive house buildings employ superinsulation to significantly reduce the heat transfer through the walls, roof and floor compared to conventional buildings. [60] A wide range of thermal insulation materials can be used to provide the required high R-values (low U-values, typically in the 0.10 to 0.15 W/(m 2 ·K) range).