Which term measures a material's ability to resist heat transmission?

The term that measures a material's ability to resist heat transmission is the R-value. The R-value quantifies thermal resistance, indicating how well a material insulates against heat flow. The higher the R-value, the greater the insulating effectiveness of the material. This is crucial in construction and energy-efficient building practices, as it influences heating and cooling costs and overall comfort within a space.

Thermal mass, while related to temperature regulation, refers to a material's ability to store and release heat rather than its resistance to heat transfer. The U-value measures the rate of heat transfer, factoring in both conduction and other types of heat flow, but it expresses the opposite of R-value—lower numbers indicate better insulation. The K-value relates to thermal conductivity, which describes how easily heat moves through a material rather than its capacity to resist that movement. Therefore, R-value is the most appropriate measure for assessing insulation effectiveness in resisting heat transmission.