Which of the following best describes a VAV (Variable Air Volume) system?

A Variable Air Volume (VAV) system is a type of heating, ventilation, and air conditioning (HVAC) system that regulates air flow in a space to maintain temperature while efficiently using energy. The correct choice highlights the characteristics of a VAV system, particularly in terms of its application in larger buildings where efficiency and comfort are paramount.

In a VAV system, the amount of air delivered to different areas of a building can be adjusted according to the needs of the space, allowing for temperature control without the waste associated with constant air flow. This method provides better energy efficiency compared to systems like fan coil units which typically operate at a fixed air flow rate, leading to higher operational costs due to constant heating or cooling.

The need for extensive ductwork is indeed a feature of VAV systems, but this characteristic does not make it a description of the system itself as much as it reflects the system's installation requirements.

Furthermore, while constant temperature control is a significant goal in HVAC design, VAV systems operate by modulating airflow rather than simply maintaining a constant temperature; hence this choice is misleading regarding their functionality.

In contrast to the affordability aspect, VAV systems tend to require more upfront investment compared to simpler systems, which emphasizes that the operational