A zone within a building is not served by any heating or cooling equipment. The designer proposes to ventilate it using only operable windows that meet the size and location requirements of Section 402.2. According to the California Mechanical Code, is a mechanical ventilation system also required for this zone?

• No, but only if the natural ventilation system is engineered and approved by the AHJ.
• No, a mechanical ventilation system is not required because the zone has no heating or cooling equipment.
• Yes, but only if the operable windows have controls that prevent them from being closed.
• Yes, a mechanical ventilation system is always required when natural ventilation is used.