What does BTU stand for and measure?

BTU stands for British Thermal Unit, and it measures heat energy. Specifically, one BTU is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit at a constant pressure. This unit of measurement is critical in the HVAC industry because it helps quantify the heating or cooling capacity of various systems, such as furnaces, air conditioners, and heat pumps. Understanding BTUs allows HVAC professionals to properly size and select equipment for heating and cooling spaces efficiently, ensuring comfort and energy efficiency in residential and commercial applications.

The other choices do not accurately describe what BTU stands for or measure, which is why they are not valid. For instance, Basic Temperature Unit is not a recognized term in HVAC, and airflow rate has no relation to BTU, which strictly pertains to heat energy. The term British Transfer Unit doesn’t exist, and it misleadingly suggests a focus on energy efficiency rather than the heat energy measurement that BTU represents.