2,400+ Definitions
HVAC GLOSSARY
Every HVAC term, acronym, and industry phrase — defined in plain English.
Insulation Resistance Test
An insulation resistance test measures the effectiveness of electrical insulation…
Integral Control
Integral control continuously adjusts valve position based on the accumulated…
Integral Windup
A condition in a PID controller where the integral term…
Integrated Collector Storage
Integrated collector storage (ICS) systems combine solar collection and thermal…
Integrated Design
Integrated design is a collaborative planning approach where HVAC engineers,…
Integrated Energy Efficiency Ratio
Integrated Energy Efficiency Ratio (IEER) measures the cooling efficiency of…
Integrated Part Load Value
Integrated Part Load Value (IPLV) represents chiller or air conditioning…
Integrated Part-Load Value
A weighted efficiency metric that accounts for equipment performance across…
Integrated Part-Load Value (IPLV)
A single-number efficiency metric for chillers defined by ARI/AHRI standards…
Intercooler
A heat exchanger used in two-stage refrigeration or booster systems…
Interlaced Defrost
A defrost scheduling strategy on multi-circuit rack systems that staggers…
Intermittent Pilot
An ignition system that energizes a spark to light a…
International Energy Conservation Code
The International Energy Conservation Code (IECC) is a model building…
Internet of Things
The Internet of Things (IoT) is a network of physical…
Interstitial Condensation
The formation of liquid water within a wall, roof, or…
Inverter Compressor
A variable-speed compressor driven by a frequency-converting drive that adjusts…
Inverter Efficiency
Inverter efficiency measures the percentage of DC power successfully converted…
IO List
An IO List (Input/Output List) documents all physical connections between…
IoT Sensor
An IoT Sensor is a connected device that continuously measures…
IPDU
An Intelligent Power Drive Unit is the inverter board assembly…
IPLV
IPLV (Integrated Part Load Value) measures chiller efficiency across varying…
IRA HVAC Rebates
IRA HVAC Rebates are federal rebate programs established under the…
IRC
Definition The International Residential Code (IRC) is a model building…
IRC Section M
The mechanical provisions within the International Residential Code that govern…
Irradiance Correction
Irradiance correction adjusts solar panel performance calculations to account for…
Isentropic Compression
Isentropic compression is a theoretical frictionless compression process where entropy…
Isentropic Efficiency
Isentropic efficiency is a thermodynamic performance metric that compares the…
Island Mode
Island mode occurs when a grid-tied solar system continues operating…
ISO Class
ISO Class is a designation from the ISO 14644-1 standard…
Isolated System
An isolated system permits no exchange of energy or mass…
Isolation Room
An isolation room is a specialized hospital space with negative…
Isolation Transformer
A transformer with separate primary and secondary windings that provides…
Isothermal Humidification
A humidification process in which steam is injected into the…
Isothermal Process
An isothermal process is a thermodynamic process in which the…
ITC
ITC stands for Investment Tax Credit, a federal incentive allowing…
Jet Fan
Jet fans are axial fans mounted in tunnel ceilings that…
Jet Throw
The horizontal or vertical distance a supply air jet travels…
Joule Thomson Effect
The Joule-Thomson Effect describes the temperature change that occurs when…
Journeyman Technician
A journeyman technician is a skilled HVAC professional who has…
Kigali Amendment
The Kigali Amendment, adopted in 2016 as an addition to…
Kilowatt
A kilowatt (kW) is a unit of power equal to…
Kilowatt Hour
A kilowatt hour (kWh) is the standard unit measuring electrical…
Kitchen Exhaust
Kitchen exhaust is the mechanically induced removal of heat, moisture,…
Kitchen Fire Suppression
Kitchen fire suppression is an automated safety system designed to…
Kitchen Hood
A kitchen hood is a ventilation device mounted above cooking…
Kitchen Ventilation
Kitchen ventilation is the complete system of air removal and…
KNX
KNX is an open-source international standard (ISO/IEC 14543-3) for home…
kW
A kilowatt (kW) measures electrical power, representing 1,000 watts of…