What is the definition of a BTU?

The definition of a BTU, or British Thermal Unit, is the heat energy required to raise the temperature of 1 pound of water by 1 degree Fahrenheit. This measurement is fundamental in understanding heating and cooling processes, as it allows professionals in the heating, ventilation, and air conditioning (HVAC) industry to quantify energy transfer related to temperature changes.

When assessing heating and cooling systems, BTUs serve as a critical unit for measuring how much energy is needed to achieve a desired temperature change, making option A the most accurate definition of a BTU. Understanding this concept is essential for determining system capacities, efficiency, and energy consumption within HVAC applications.