Which concept describes how well a material can maintain heat without transferring it?

The concept that describes how well a material can maintain heat without transferring it is thermal resistance. Thermal resistance refers to the ability of a material to resist the flow of heat. A material with high thermal resistance will not easily transfer heat through it, which is advantageous for insulation. This is important in various applications, such as building insulation, where the goal is to keep heat from escaping or entering a space.

In contrast, thermal conductivity measures how well a material conducts heat; a material with high thermal conductivity will transfer heat quickly. Thermal inertia relates to how a material can absorb and store heat over time, impacting temperature changes within that material. Thermal efficiency pertains to how effectively a system converts input energy into useful work or heat without excessive losses. Thus, thermal resistance is directly related to the maintenance of heat without transferring it, making it the correct concept in this context.