Ventilation

The circulation of air in a room or building;  a process of changing the air in a room by natural or artificial means.  The process of supplying or removing air, by natural or mechanical means to and from a space. Ventilation refers to air movement between zones. The American Society Of Heating Refrigeration And Air Conditioning Engineers (ASHRAE) standard 62-1989 provides guidance on general ventilation and indoor air quality. Recommended ventilation is 15 cubic feet of air per minute (cfm), per person. Typically, this equals a one-third exchange of air per hour in a residential home.

Ventilation Air

That portion of supply air that is outdoor air plus any recirculated air that has been treated for the purpose of maintaining acceptable indoor air quality.

Ventilation Effectiveness

An expression describing the ability of a mechanical (or natural) ventilation system to remove pollution originating in a space, either of a steady state or transient nature.

Ventilation Efficiency

Measure of how quickly a contaminant is removed from the room.

Ventilation Heat Loss/Or Gains

The heat lost or gained by virtue of warm and/or humid air flowing into or leaking from a space.

Ventilation Rate

The rate at which outside air is intentionally supplied to a building or zone. Sometimes ventilation is used to describe the total mechanical air change in a room or building. This rate may then frequently comprise a considerable proportion of recirculated rather than outdoor air. Hence when apparently very large ventilation rates are quoted, it is important to establish the proportion of flow representing outside supply air. The remainder will be recirculated air.

Ventilator

A ventilator captures heating or cooling energy from stale indoor air and transfers it to fresh incoming air.

Vestibule

A small entrance hall to a building or room.

VFD

An acronym for Variable Frequency Drive - Electronic speed control for motors.

Vinyl

Polyvinyl chloride material, which can be both rigid or flexible, used for window frames. A man-made plastic material.  Recently used to replace aluminum in siding and windows.

Vinyl-Clad Window

A window with exterior wood parts covered with extruded vinyl.

Viscosity

The friction or resistance to the flow of a liquid.

Visible Light

The portion of the electromagnetic spectrum that produces light that can be seen. Wavelengths range from 380 to 720 nanometers.

Visible Transmittance (VT)

The percentage or fraction of the visible spectrum (380 to 720 nanometers) weighted by the sensitivity of the eye, that is transmitted through the glazing.

Volt (V)

Unit of measurement denoting electrical pressure or potential (usually abbreviated V).  The practical meter-kilogram-second unit of electrical potential difference and electromotive force equal to the difference of potential between two points in a conducting wire carrying a constant current of one ampere when the power dissipated between these two points is equal to one watt and equivalent to the potential difference across a resistance of one ohm when one ampere is flowing through it. Typical chiller voltages are 460, 480, 2400 or 4160. This information can be found in the chiller technical documentation.

Wainscot

A facing or panel that is applied to the walls of a room. The lower part of an interior wall that is finished with a material different from the upper part.

Wall

A vertical structure of stone, brick, wood or other similar material that encloses, divides supports and protects e.g., one of the vertical enclosing sides of a building or room.

Wall Furnace

A small, gas-fired hot air furnace that fits between the studs of a wall has no ducts uses a small fan to circulate room air through the furnace and to distribute heated air.

Wallboard

Any artificially prepared sheet materials or panels that are used to cover walls or ceilings as a substitute or base for plaster .

Warm Air System

A heating system in which furnace-heated air moves to living space through a single register or series of ducts circulated by natural convection (gravity system) or by a fan or blower in the duct work (forced system).

Warm-Edge Technology

The use of low-conductance spacers to reduce heat transfer near the edge of insulated glazing.

Washer

Flat disc with a center hole sued under a screw, bolt or nut.

Water Defrosting

The use of water to melt ice and frost from evaporator during off-cycle.

Water Treatment Program

A water treatment program provides a biocide program that minimizes microbiological growth along with excellent scale/corrosion protection.

Water-Cooled Condenser

A condensing unit which is cooled through use of water.

Waterproofing

To make impervious to water or dampness.

Watt (W)

A measure of electricity equal to the power created by a current of one ampere flowing at one volt pressure. A watt is a unit of electricity.

Wax

An ingredient in many lubricating oils which may separate out if cooled sufficiently.

WC/Water Closet

Room containing toilet and wash basin.

Wear And Tear

Loss or damage resulting from use.

Weatherstrip

A thin strip of metal, felt, wood, etc., that is used to cover the joint between a door or window sash and the jamb, casing or sill keeps out air, dust, rain, etc.

Weatherstripping / Weather Stripping

A strip of resilient material for covering the joint between the window sash and frame in order to reduce air leaks and prevent water from entering the structure. Metal, wood, plastic or other material installed around door and window openings to prevent air infiltration.

Weep Hole

A small opening in a wall or window sill member through which water may drain to the building exterior.

Wet Bulb

A device used in measurement of relative humidity. Evaporation of moisture lowers temperature of wet bulb compared to dry bulb temperature in same area.

Wet Bulb Temperature

Air temperature indicated by a sensing element kept wet (usually by a wick), the indicated temperature thus being related to the rate of evaporation from the wetted bulb. This wet bulb temperature is used by psychrometers to measure the relative humidity.

Wet-Sanding

Using water and fine sandpaper with a waterproof blacking, known as wet-or-dry paper, to achieve a smooth finish on joint compound without clogging the sandpaper's abrasive grains.

Wind Barrier

A barrier designed to obstruct wind flow and intended for protection against excessive wind pressure.