How is “heat loss” defined in the context of buildings?

In the context of buildings, "heat loss" is specifically defined as the transfer of heat out of a building. This concept is crucial in understanding how buildings maintain temperature, especially during colder months. Heat loss occurs through various pathways, including conduction through walls, windows, and roofs, as well as air leakage and ventilation. This loss of heat must be compensated for in order to maintain a comfortable indoor environment, often leading to increased heating costs and energy consumption. Understanding heat loss helps in designing more efficient building envelopes, improving insulation, and utilizing HVAC systems more effectively to reduce energy waste and enhance thermal comfort.