2,400+ Definitions
HVAC GLOSSARY
Every HVAC term, acronym, and industry phrase — defined in plain English.
Passive Cooling
Passive cooling uses natural ventilation, shading, thermal mass, and evaporative…
Passive Design
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
PCM Wallboard is a building material embedded with phase-change materials…
Peak Demand
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
Peak sun hours are the equivalent number of hours per…
Peak Watt
A peak watt (Wp) is the unit of measurement for…
Peltier Effect
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 Pipe
PEX (cross-linked polyethylene) pipe is a flexible plastic tubing used…
Pharmaceutical HVAC
Pharmaceutical HVAC systems maintain sterile, controlled conditions for drug manufacturing…
Phase
Phase describes the timing or position of an alternating current…
Phase Change Material
Phase change materials (PCMs) are substances that absorb, store, and…
Phase Diagram
A phase diagram graphically displays the regions where substances exist…
Photocatalytic Oxidation
Photocatalytic oxidation uses ultraviolet light and titanium dioxide catalysts to…
Photovoltaic
Photovoltaic (PV) refers to the technology that directly converts sunlight…
Physical Adsorption
Physical adsorption is the process of gas and odor molecules…
PID Control
PID (Proportional-Integral-Derivative) control is an automatic feedback algorithm that continuously…
Pilot Light
A pilot light is a small, continuously burning flame that…
Pipe Anchor
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…
Pipe Guide
A pipe guide is a low-friction device that allows controlled…
Pipe Hanger
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…
Pipe Insulation
Pipe insulation is a protective covering applied to hot or…
Pipe Pressure Drop
Pipe pressure drop is the reduction in pressure that occurs…
Pipe Schedule
A Pipe Schedule is a detailed table specifying all piping…
Pipe Sizing
Pipe sizing is the process of selecting appropriate pipe diameters…
Pipe Slope
Pipe slope is the intentional grade or tilt applied to…
Pipe Support
A pipe support is a structural element that bears pipe…
Pipe Velocity
Pipe velocity measures the speed at which fluid flows through…
Piping System Design
Piping System Design involves sizing and routing water or refrigerant…
Pitot Tube Traverse
A pitot tube traverse is a method for measuring air…
Plate Heat Exchanger
A plate heat exchanger consists of thin metal plates stacked…
Pleated Filter
Pleated filters feature accordion-like folds in the filter media that…
Plenum
A plenum is a chamber or box used to distribute…
Plenum Rated
Plenum rated refers to materials that meet strict fire safety…
Plenum Space
Plenum space is the cavity or chamber above a suspended…
PM 2.5
PM2.5 refers to particulate matter with a diameter of 2.5…
PMV
PMV (Predicted Mean Vote) is a numerical index that predicts…
Pneumatic Actuator
A pneumatic actuator uses compressed air pressure (typically 15-25 PSI)…