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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]
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]
The basic unit of insulation coefficient is the R SI, (1 m 2 ⋅K/W). 1 tog = 0.1 R SI. There is also a US clothing unit, the clo , equivalent to 0.155 R SI or 1.55 tog, described in ASTM D-1518. [ 7 ]
Thermal insulance (R-value) is a measure of a material's resistance to the heat current. It quantifies how effectively a material can resist the transfer of heat through conduction, convection, and radiation.
Architects and engineers call the resulting values either the U-Value or the R-Value of a construction assembly like a wall. Each type of value (R or U) are related as the inverse of each other such that R-Value = 1/U-Value and both are more fully understood through the concept of an overall heat transfer coefficient described in lower section ...
R-value or rvalue may refer to: R-value (insulation) in building engineering, the efficiency of insulation of a house; R-value (soils) in geotechnical engineering, the stability of soils and aggregates for pavement construction; R-factor (crystallography), a measure of the agreement between the crystallographic model and the diffraction data
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.
EPS is the most common of the foams used and has an R-value (thermal resistance) of about 4 °F·ft 2 ·h/Btu (equivalent to about 0.7 K·m 2 /W) per 25 mm thickness, which would give the 3.5 inches (89 mm) of foam in a 4.5-inch-thick (110 mm) panel an R value of 13.8 (caution: extrapolating R-values over thickness may be imprecise due to non ...