2,400+ Definitions
HVAC GLOSSARY
Every HVAC term, acronym, and industry phrase — defined in plain English.
kWh
A kilowatt-hour (kWh) is the standard unit measuring electrical energy…
Laboratory HVAC
Laboratory HVAC systems are specialized climate control installations designed to…
Laminar Flow
Laminar flow refers to air movement in parallel layers at…
Laser Alignment
Laser alignment is a precision measurement technique using laser beams…
Latent Heat
Latent heat is the thermal energy absorbed or released when…
Latent Heat Gain
The cooling load component caused by moisture entering a conditioned…
Latent Heat of Fusion
Latent heat of fusion is the quantity of thermal energy…
Latent Heat of Vaporization
Latent heat of vaporization is the energy required to convert…
Latent Heat Ratio
Latent Heat Ratio (LHR) measures the proportion of total cooling…
Latent Heat Recovery Efficiency
The ratio of moisture-related energy actually transferred by an energy…
Latent Heat Storage
Latent heat storage is a thermal energy storage method that…
LCOE
LCOE (Levelized Cost of Energy) is the average cost per…
Lead Acid Battery
Lead acid batteries are electrochemical devices using lead oxide cathodes…
Leak Testing
Leak testing is the diagnostic process of detecting refrigerant leaks…
Leakage Distribution
The characterization of where air leakage occurs across different components…
Learning Thermostat
A learning thermostat is an intelligent control device that automatically…
LEED
Definition Leadership in Energy and Environmental Design (LEED) is a…
LEED Certification
LEED Certification is an official credential awarded by the U.S.…
LEED Certified
LEED Certified is the entry-level LEED credential, awarded to buildings…
LEED Energy Credit
LEED Energy Credits are certification points awarded for demonstrated energy…
LEED Gold
LEED Gold is the third-highest certification tier awarded to buildings…
LEED Platinum
LEED Platinum is the highest LEED certification tier, awarded to…
LEED Point
A LEED Point represents one credit earned toward LEED certification,…
LEED Silver
LEED Silver is the second-lowest LEED certification tier, awarded to…
Legionella Prevention
Legionella prevention encompasses water treatment strategies and maintenance protocols designed…
Levelized Cost of Energy
Levelized Cost of Energy (LCOE) is the total lifecycle cost…
LGWP refrigerant
A broad industry shorthand for any refrigerant with a low…
Licensed Contractor
A licensed contractor is a business entity or individual authorized…
Lift (Refrigeration)
The pressure differential a compressor must overcome, defined as the…
Light-to-Solar-Gain Ratio
Another term for the selectivity index, comparing a window’s visible…
Limit Switch
A limit switch is a safety device that automatically opens…
Limit Switch Test
A limit switch test checks whether furnace or boiler temperature-limiting…
Line Hide
A decorative plastic channel raceway system used to conceal refrigerant…
Line Set Cover
A line set cover is a protective conduit or sleeve…
Line Set Insulation
Line set insulation is foam or flexible rubber material wrapped…
Linear Diffuser
A linear diffuser is an elongated air distribution outlet featuring…
Linear Power Warranty
A linear power warranty guarantees solar panel output declines at…
Linear Valve
A linear valve is a control valve where equal increments…
Liner Thickness
The depth of insulating or acoustic material applied inside a…
Lineset
A lineset is the complete assembly of refrigerant carrying tubes,…
Liquid Charging
Introducing refrigerant into the high side of a system in…
Liquid Cooling Data Center
A Liquid Cooling Data Center uses water, oil, or other…
Liquid Desiccant
Liquid desiccant cooling uses aqueous solutions, typically lithium chloride or…
Liquid Injection Cooling
A method of controlling compressor discharge temperature by injecting a…
Liquid Line
The liquid line is the section of refrigerant piping in…
Liquid Line Filter Drier
A liquid line filter drier is a refrigeration system component…
Liquid Line Solenoid Valve
An electrically operated shutoff valve installed in the refrigerant liquid…
liquid subcooler
A heat exchanger that removes additional heat from liquid refrigerant…