Pollution

An unwanted by-product of human activity. The presence of matter or energy whose nature, location, or quantity produces undesired environmental effects.

Pollution Source

Any object animate or inanimate, usually within the building, which produces a substance which will contaminate the internal environment, for example, animal dander, plant pollen, smoke, etc.

Poor

In below-average condition given its age and function, will need substantial repair or replacement in the reasonably near future, showing definite signs of wear and/or usage.

Porte Cochere

A roof that extends from a building's entrance over an adjacent driveway to shelter people getting in or out of vehicles.

Portico

A roof supported by columns, either part of a building or standing alone.

Positive Pressure

A condition that exists when more air is supplied to a space than is exhausted, so the air pressure within that space is greater than that in surrounding areas.

Power Factor

A term used to quantify the amount of reactive power being generated/absorbed at a particular point in an electrical circuit. 

PPM

An acronym for parts per million

Pressure

The application of force to something by something else in direct contact with it.

Pressure Drop

The reduction in pressure between a fluid entering and leaving a closed system.

Pressure Gauge

An instrument that measures pressure in psig, psid or psia depending on the circumstances.

Pressure, Total"

In flowing air, the sum of the static pressure and the velocity pressure.

Pressure, Velocity"

In flowing air, the pressure due to the velocity and density of the air.

Pressurization

A method of testing air leakage of a building or component by installing a fan in the building envelope, for example through a door or window, and creating a static pressure excess inside the building. The airflow rate through the fan and the pressure difference across the envelope are measured from which the air leakage is assessed.

Pretreatment

The removal of oil and grease from new piping and chillers to ensure maximum heat transfer. It should also lay down a passivating film to prevent flash corrosion and in some cases, white rust.

Primary Surface Area

The area that contains the working heat transfer fluid. Usually the tubes of a finned/tube heat exchanger.

Primary Windows And Doors

Windows and/or doors which are designed to remain in their respective openings year round and not left open for the entire summer.

Prime

To apply an undercoat of paint or sealer to seal pores of wood and provide a surface to which finish coats can adhere.

Productivity

The efficiency with which a person performing a specific function does a job or the output of a worker under specific environments and conditions.

Programmed Start/Stop

An energy management function, which operates to selectively shutdown electrically operated equipment. This is accomplished on a predetermined time-schedule, usually paralleling occupancy schedules.

Projected Window

A window fitted with one or more sashes opening on pivoted arms or hinges. Refers to casements, awnings, and hoppers.

PRV

Pressure Release Valve. Serves as a safety device on water heaters and boilers.

PTL

Pressure Treated Lumber. Resistant to water and insects.

Public Building

A building which is open to the public, such as museums, clubs, public houses, exhibition halls etc.

Pulley

A wheel grooved to receive a cord, cable, or belt, such as in a window sash, roll-up garage door, or blower.

Pump

A device used to circulate fluid from one location to another.

Pump Curve

The design capacity of a pump's ability to circulate fluid.

Pump Curve Calibration

A flow test to determine the capacity of a pump's ability to circulate fluid.

Pumpout System

Pumpout systems consist of a storage tank large enough to hold the entire refrigerant charge and a refrigerant pump/compressor to move the refrigerant from the heat pump/air conditioner to the pumpout tank and back again.

Purge Unit

Removes non-condensable gasses (air) from the condenser barrel.

PVC

Polyvinyl chloride (plastic) used for condensate lines, and electrical wire incasements. An extruded or molded plastic material used for window framing and as a thermal barrier for aluminum windows.

Pyramid Roof

A roof with four sides and four ridges that resembles a pyramid usually comes to a point in the center.

Quality

The ratio of vapor mass to total mass of a substance at the substance's saturation temperature and pressure.

Quick Connect Coupling

A device which permits easy, fast, connecting of two fluid lines.

Quick-Setting Cement

An asphalt-based cement used to adhere tabs of strip shingles to the course below. Also used to adhere roll roofing laps applied by the concealed nail method.

Racking

Roofing application method in which shingle courses are applied vertically up the roof rather than across and up. NOT a recommended procedure.

Radial Commutator

An electrical contact surface on a rotor which is perpendicular or at right angles to the shaft center line.

Radiant

System that uses hot surfaces to radiate or convect heat into the environment. Without the use of fans or blowers

Radiant Heat

Coils of electricity, hot water or steam pipes embedded in floors, ceilings, or walls to heat rooms.

Radiant Heat Transfer

Radiant heat transfer occurs when there is a large difference between the temperatures of two surfaces that are exposed to each other, but are not touching.

Radiant Heating

A type of steam, electric or hot water heat that uses pipes concealed in floors, ceilings or walls.  A heating system in which warm or hot surfaces are used to radiate heat into the space to be conditioned.

Radiation

A transmission of heat, through space, by the propagation of infrared energy. The passage of heat from one object to another without necessarily warming the space between. Radiation does not need a transport medium and so it can take place in vacuum (or in space i.e. Solar radiation). Heat and light are forms of electromagnetic radiation  other forms are microwaves, x-rays, radio broadcast waves. The different forms of electromagnetic radiation differ in wavelength and frequency. . The transfer of heat in the form of electromagnetic waves from one separate surface to another. Energy from the sun reaches the earth by radiation, and a person's body can lose heat to a cold window or skylight surface in a similar way.

Radiator

An exposed fixture that heats with a combination of radiation and convection e.g. The common, cast-iron radiator as distinguished from convectors, finned heating elements that are concealed in walls or cabinets, e.g., baseboard heating.