What does power measure?

Power measures the rate at which work is done or heat is released within a system. This concept is crucial in understanding the efficiency of energy use in various applications, particularly in buildings where energy consumption and energy efficiency are important concerns.

When power is discussed, it refers to how quickly energy is transferred or converted from one form to another, which is often expressed in units such as watts. For instance, when a light bulb operates, it does so at a specific power level, indicating how much electrical energy it converts into light (and heat) over time.

The total energy in a system pertains to a different aspect — it quantifies the total amount of energy available, regardless of the rate at which it is being used. Similarly, temperature is a measure of thermal state rather than energy transfer, and capacity for energy transformation describes the potential for energy changes without specifying the rate at which these transformations occur. Therefore, the focus on the rate of work or heat release clearly defines power.