R-values can be calculated by dividing the thickness of a material (in metres) by its thermal conductivity (k-value or lambda value (λ) in w/mk). R-values are therefore expressed in m2k/w (or ft2·°f·hr/btu in the usa).
How Is R Value Calculated?
R-value is a measure of thermal resistance used in the building and construction industry to quantify how well a material can resist heat flow. This measure is also used to compare the energy efficiency of different building components, such as insulation, windows, and doors. Calculating R-value is not as difficult as it may seem and is an important part of any energy efficiency project.
R-value is expressed in units of thermal resistance, which is a measure of the ability of a material or construction to resist the flow of heat. The higher the R-value, the greater the resistance to heat flow and the better the energy efficiency of the material or construction.
To calculate the R-value of a material, one must first calculate the thermal conductivity of the material. Thermal conductivity is a measure of how easily heat is conducted through a material, and it is expressed in units of watts per meter Kelvin (W/mK). Thermal conductivity is determined by measuring the rate at which heat moves through a material, and it is affected by the type of material, its thickness, and its density.
Once the thermal conductivity is determined, it can be used to calculate the R-value of the material. The formula for calculating R-value