What is thermal resistance commonly known as?

Thermal resistance is commonly known as R-value. This value quantifies how well a material resists the flow of heat. In practical terms, a higher R-value indicates better insulating properties, meaning that the material is more effective at resisting heat transfer. The R-value is essential when evaluating building materials for their ability to keep heat in during the winter and out during the summer, contributing to energy efficiency in construction.

The other terms presented have distinct meanings: U-value refers to the rate of heat transfer through a material, which is essentially the inverse of R-value. Conductivity measures a material's ability to conduct heat, while insulation value is a more general term that can encompass several factors about a material's thermal performance but is not a standardized measure like R-value.