What is the purpose of outside air?

The purpose of outside air in HVAC systems primarily relates to maintaining required oxygen levels within a building. Regularly introducing outside air helps ensure that indoor air quality remains healthy for occupants, providing them with the necessary oxygen for breathing while also diluting indoor air pollutants and maintaining a fresh air supply. This is crucial in spaces where activities may reduce indoor oxygen levels or increase carbon dioxide concentrations, such as in crowded offices or buildings with limited ventilation.

In many HVAC designs, bringing in outside air is a necessary function to comply with building codes and standards aimed at ensuring the safety and comfort of occupants. While other options may touch on important aspects of HVAC operation, the introduction of outside air specifically targets the need to maintain proper oxygen levels, which is vital for occupant health and well-being.