Mechanical Code Chapter 4 Section 403.2 Outdoor air required

Building codes require ventilation systems to be capable of providing minimum outdoor airflow based on the peak number of people expected in a space. While systems must be engineered for maximum occupancy, designers can use validated statistical data to adjust these requirements for more accurate local needs. Professionals may also implement customised engineering designs that lower intake rates provided they effectively regulate indoor pollutants and maintain air safety. These systems must function without interruption whenever the building is in use to ensure a constant supply of fresh air. Furthermore, if smoking is permitted, the mechanical setup must provide additional airflow beyond standard baseline levels. Ultimately, these guidelines aim to balance high-capacity safety with operational energy efficiency through precise technical planning.