What does a British Thermal Unit (BTU) measure?

A British Thermal Unit (BTU) is specifically defined as a unit of measure for heat energy. It quantifies the amount of energy required to raise the temperature of one pound of water by one degree Fahrenheit at a constant pressure. This makes BTUs a standard reference in fields dealing with heating and energy consumption, such as HVAC (heating, ventilation, and air conditioning) installations, cooking, and various industrial processes. Understanding BTUs is essential for evaluating energy efficiency and the energy input needed for various heating applications, making it a fundamental concept in utility marketing and energy management.