In heat transfer calculations, what is primarily measured in BTUs?

In heat transfer calculations, the primary measurement in British Thermal Units (BTUs) is heat energy. A BTU is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. This measurement is fundamental in various applications, such as HVAC systems, where it's essential to quantify heat energy for heating, cooling, and energy efficiency calculations.

Understanding BTUs is crucial for engineers and technicians because it helps in evaluating heating and cooling systems, allowing them to determine the energy efficiency and performance of these systems. In the context of system design or troubleshooting, knowing the heat energy in BTUs enables operators to make informed decisions about the capacity and capabilities of refrigeration and air conditioning units.