##  [R-Value](/r-value) 

  ##  [R-Value](https://engineering.quantumdictionary.io/r-value-0) 

  

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**Engineering & Applied Technologies Dictionary**

 







 

 

 

 



 

 

 

 

Definition

Thermal resistance per unit area of a material layer or an assembly, expressed as the temperature difference across it per unit steady heat flux (commonly m²·K·W⁻¹). For a homogeneous layer, R = thickness / k; for assemblies R_total is the sum of individual resistances including defined surface resistances when stated.