Which HVAC design is most common in modern public and midrise commercial buildings?

• A. Constant Volume
• B. Packaged Terminal Air Conditioner
• C. Variable Air Volume (VAV)
• D. Heat Recovery Ventilation

Answer: (C)

In modern public and midrise commercial buildings, varying the amount of supply air to different zones is the prevailing approach. A variable air volume system delivers cooling or heating by adjusting the volume of air rather than constantly pushing the same amount of air everywhere, which fits the diverse and shifting loads across offices, lobbies, and other spaces. The central air handler provides a fairly constant supply-air temperature, while VAV boxes in each zone modulate dampers to meet individual zone temps; some zones may use reheat to fine-tune comfort. This zoning capability reduces energy use and improves comfort across many spaces with different occupancy and load patterns, making it the most common design. Constant-volume systems waste energy by supplying the same airflow regardless of demand. Packaged terminal units are typically used in hotels or smaller applications, not as the main building-wide design. Heat recovery ventilation is a valuable efficiency feature but not the standard system type for the entire building.