What term describes the measure of the rate of heat transfer to or from one surface to another?

The term that describes the measure of the rate of heat transfer to or from one surface to another is heat flux. Heat flux quantifies how much thermal energy is being transferred per unit area and per unit time, typically expressed in units such as watts per square meter (W/m²). This concept is crucial in understanding heat transfer processes, particularly in firefighting operations where managing heat is vital for both safety and effectiveness.

In contrast, heat capacity defines the amount of heat energy required to change the temperature of an object by a certain amount, but it does not account for the area or rate of transfer. Thermal conductivity refers to the property of a material that indicates its ability to conduct heat, which is a factor in the overall heat transfer process but does not represent the rate of heat transfer itself. Specific heat is a measure of how much heat a substance can hold per unit mass per degree of temperature change and is also not directly related to the rate of heat transfer between surfaces.