value engineering: The systematic effort of analyzing planned or designed building features and systems to achieve acceptable performance, function, and safety at the lowest service life cost.

valve: a device used in piping to control the gas or liquid supply downstream of the device.

vapor retarder: a vapor-resistant material, membrane or covering, such as foil, plastic sheeting or insulation facing, that limits the amount of moisture vapor that passes through a material or wall assembly.

variable air volume system: Air handling system that conditions the air to a constant temperature and varies the outside airflow to ensure thermal comfort.

VAV: Variable air volume system.

ventilation: the natural or mechanical process of supplying and removing air from any space.

ventilation air: Defined as the total air, which is a combination of the air brought into the system from the outdoors and the air that is being recirculated within the building. Sometimes, however, used in reference only to the air brought into the system from the outdoors.

verify: to confirm or substantiate.

visible: that which may be easily observed during the walk-through survey portion of the inspection.

VOCs: See “Volatile Organic Compounds.”

volatile organic compounds (VOCs): Compounds that evaporate from the many housekeeping, maintenance, and building products made with organic chemicals. These compounds are released from products that are being used and that are in storage. In sufficient quantities, VOCs can cause eye, nose, and throat irritations, headaches, dizziness, visual disorders, memory impairment; some are known to cause cancer in animals; some are suspected of causing, or are known to cause, cancer in humans. At present, not much is known about what health effects occur at the levels of VOCs typically found in public and commercial buildings.