What does the term "forced air" refer to in HVAC systems?

The term "forced air" in HVAC systems specifically refers to a system that employs a fan or blower to circulate air through a network of ducts. This method is commonplace for both heating and cooling because it effectively distributes conditioned air throughout a space, ensuring that the environment remains comfortable.

In forced air systems, the process generally involves taking air from the surrounding area, tempering it (either heating or cooling it), and then moving it through ducts to various rooms. This method provides more control over indoor temperatures and can enhance air quality when equipped with appropriate filters.

On the other hand, methods that rely on radiation or passive solar energy do not use fans or ductwork to move air, while natural ventilation involves allowing outside air to flow into a building without mechanical intervention. These alternatives lack the efficiency and control over airflow and temperature offered by a forced air system.