Letter V

VAV System (Variable Air Volume System) - A mechanical HVAC system capable of serving multiple zones which controls the temperature maintained in a zone by controlling the amount of heated or cooled air supplied to the zone.

VAPOR BARRIER - A material with a permeance of one perm or less which provides resistance to the transmission of water vapor. [See California Code of Regulations, Title 24, Section 2-5302]


VERIFICATION PHASE - The step of the California Energy Contingency Plan to determine the existence and scope of an energy shortage and report to Energy Commission executives, the Governor and the Legislature where required under the plan.

VERTICAL INTEGRATION - An arrangement whereby the same company owns all the different aspects of making, selling, and delivering a product or service. In the electric industry, it refers to the historically common arrangement whereby a utility would own its own generating plants,transmission system, and distribution lines to provide all aspects of electric service.

VISIBLE LIGHT TRANSMITTANCE -- The ratio of visible light transmitted through a substance to the total visible light incident on its surface.


- VOLTAGE OF A CIRCUIT (Electric utility) - The electric pressure of a circuit, measured in volts. Usually a nominal rating, based on the maximum normal effective difference of potential between any two conductors of the circuit.

VOLUMETRIC WIRES CHARGE - A type of charge for using the transmission and/or distribution system that is based on the volume of electricity that is transmitted.