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The R-value is the building industry term [3] for thermal resistance "per unit area." [4] It is sometimes denoted RSI-value if the SI units are used. [5] An R-value can be given for a material (e.g. for polyethylene foam), or for an assembly of materials (e.g. a wall or a window). In the case of materials, it is often expressed in terms of R ...
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.
Provisions in the commercial sector of the model codes affect building design and construction factors such as: thermal envelope, water heating, HVAC, and lighting systems. [7] [22] In the 2021 IECC model code, for example, there are provisions that reference ASHRAE 90.1 concerning insulation R-values for opaque parts of the building envelope. [22]
Building insulation is material used in a building (specifically the building envelope) to reduce the flow of thermal energy. While the majority of insulation in buildings is for thermal purposes, the term also applies to acoustic insulation , fire insulation , and impact insulation (e.g. for vibrations caused by industrial applications).
While open-cell foams typically have R-values of 3 to 4 per inch (RSI-0.53 to RSI-0.70 per inch), closed-cell foams can attain R-values of 5 to 8 per inch (RSI-0.88 to RSI-1.41 per inch). This is important if space is limited, because it allows a thinner layer of insulation to be used.
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.
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
Next the material for the air control layer is chosen to provide a suitable air flow rate at the chosen depressurisation, taken as 10 Pa in this case. (The air flow rate could be determined from the desired U-value at the depressurisation of 10 Pa.) From Table 4, fibreboard has an appropriate air permeability of 1.34x10 −3 (m 2 /hPa).