2,400+ Definitions

HVAC GLOSSARY

Every HVAC term, acronym, and industry phrase — defined in plain English.

All A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

The P-H diagram is a graphical representation of thermodynamic properties…

PACE (Property Assessed Clean Energy) financing allows property owners to…

A package unit is a self-contained HVAC system in which…

Packaged Heat Pump

A packaged heat pump is a self-contained HVAC system that…

Packaged Rooftop Unit

A Packaged Rooftop Unit (RTU) is a self-contained HVAC system…

A packaged unit (also called a packaged system or rooftop…

Packaged Unit Installation

Packaged unit installation involves mounting a single heating and cooling…

Panel filters are flat, rectangular air filters constructed from woven…

Parabolic Trough

A parabolic trough is a concentrating solar collector with a…

Parallel Fan Powered Box

A parallel fan powered box is a type of variable…

A parallel rack is a refrigeration system configuration where multiple…

Parking Garage Ventilation

Parking garage ventilation systems remove vehicle exhaust, carbon monoxide, and…

Part Load Value

Part Load Value (PLV) is a single-number efficiency metric that…

Particulate Matter

Particulate matter (PM) consists of tiny solid particles and liquid…

Particulate Monitor

A particulate monitor measures airborne dust and fine particle concentrations,…

A pascal (Pa) is the metric unit of pressure measurement…

Passive Chilled Beam

A passive chilled beam is a ceiling-mounted or ceiling-suspended heat…

Passive Cooling

Passive cooling uses natural ventilation, shading, thermal mass, and evaporative…

Passive design uses building orientation, envelope properties, and thermal mass…

Passive Heating

Passive heating captures and retains solar energy and internal heat…

Passive House Standard

The Passive House Standard is a rigorous, voluntary building energy…

Passive Solar System

A passive solar system operates without mechanical pumps or electrical…

PCM Wallboard is a building material embedded with phase-change materials…

Peak demand refers to the highest amount of electrical power…

Peak Demand Charge

A peak demand charge is a utility billing component that…

Peak sun hours are the equivalent number of hours per…

A peak watt (Wp) is the unit of measurement for…

The Peltier effect is a thermoelectric phenomenon where direct electrical…

Performance Rating Method

The Performance Rating Method is the primary energy compliance approach…

Performance Testing

Performance testing measures an HVAC system’s ability to meet design…

Perimeter Heating

Perimeter heating is a heating strategy that places heat sources…

PEX (cross-linked polyethylene) pipe is a flexible plastic tubing used…

Pharmaceutical HVAC

Pharmaceutical HVAC systems maintain sterile, controlled conditions for drug manufacturing…

Phase describes the timing or position of an alternating current…

Phase Change Material

Phase change materials (PCMs) are substances that absorb, store, and…

A phase diagram graphically displays the regions where substances exist…

Photocatalytic Oxidation

Photocatalytic oxidation uses ultraviolet light and titanium dioxide catalysts to…

Photovoltaic (PV) refers to the technology that directly converts sunlight…

Physical Adsorption

Physical adsorption is the process of gas and odor molecules…

PID (Proportional-Integral-Derivative) control is an automatic feedback algorithm that continuously…

A pilot light is a small, continuously burning flame that…

A pipe anchor is a rigid fastening device that locks…

Pipe Freeze Protection

Pipe freeze protection encompasses strategies and materials used to prevent…

Pipe Friction Loss

Pipe friction loss describes the pressure decrease caused by friction…

A pipe guide is a low-friction device that allows controlled…

A pipe hanger is a support device that suspends pipe…

Pipe Heat Trace

Pipe heat trace is an electric heating system installed along…

Pipe Installation

Pipe installation involves placing copper, PVC, or polyethylene tubing for…