Ultimate Glossary to Understanding Window Acronyms

Understanding a completely different world than your own can be difficult. Especially if that word comes with its own language. Despite being English still, there are a ton of acronyms, governing bodies, and weird lingo floating around when talking about windows.

They’re just windows! Why the heck is everything so complicated?

This glossary will give you everything you need to know to understand windows at the same level as window manufacturers, contractors, and installers.

Window Acronyms in Alphabetical Order

AAMA – American Architectural Manufacturers Association – an association that creates standards for air leakage, wind resistance, durability, forced entry resistance, energy efficiency, thermal window performance, and water penetration

AAMA Gold – AAMA certification for window testing that portrays high-quality windows with good performance. Here are some of the important performance requirements for windows.

AAMA Silver – AAMA certification related to thermal performance and condensation resistance without certification for air, water, and structural performance. A silver certification can be performed in addition to the gold certification.

AL – Air Leakage – used to indicate that a seal is broken and that air is going through the window

Alum Aluminum – a material used for window frames that is sturdy and rigid

ADL – Authentic Divided Lite also known as True Divided Lite – a window made of multiple small panes of glass that are separated by grids

ASTM – American Society for Testing and Materials – an organization that develops international standards of testing and publishing standards on materials, products, services, and systems

AW – Awning Window – a window that opens up via a hinge on the top side, see this article for an image

CDD – Cooling Degree Day – a measure of how hot the temperature was on any given day or days using a standard temperature (usually 65°F), a temperature of 85°F would have a HDD of 20 by taking the actual temperature and subtracting the standard temperature from it

CG – Clear Glass – glass that is completely see through, not obscured

CR – Condensation Resistance Rating – a number used to indicate whether a window is more susceptible to condensation, this number is created by the NFRC, values range between 1 and 100, a higher number means the window is more resistant

CRF – Condensation Resistance Factor – a number used to indicate whether a window is more susceptible to condensation, made by the AAMA, based on different measurements of the window frame’s temperature, not as reliable as CR

DG Double Glazing – a window with two window panes, also known as double-pane

DH – Double Hung – a sash window where there are two sashes that can slide up and down vertically, read more about double-hung windows here

DP – Design Pressure – a number used to determine the wind load of a component, a higher number means the window can withstand more wind, water, and structural load

FG – Fixed Glazing – also known as a picture window or a fixed window, a window that does not open

FO – Finished Opening – the final size of the window opening after the window has been installed, different from rough opening

FR – Frame – the exterior support structure of the window, see this article for the anatomy of a window

FRG – Fire Resistant Glazing – a pane of glass that is specially treated to resist fire and smoke, slows down the spread over time

FS – Fire Shutter – a door or curtain that drops to stop a fire and contain it in one area

GBG – Grilles Between Glass – a double-pane window with the grids between the two panes instead of on the outside

HDD – Heating Degree Day – a measure of how cold the temperature was on any given day or days using a standard temperature (usually 65°F), a temperature of 30°F would have a HDD of 35 by taking the standard temperature and subtracting the actual temperature from it

HSW – Horizontal Sliding Window – a slider window that opens by sliding a sash side to side

IBC – International Building Code – a set of standards that define the minimum for how buildings should be built, used to ensure safeguards for public health and safety are in place, learn more about the IBC here

IG – Insulating Glass – windows that are made of at least 2 or more pieces of glass, also known as double-pane or triple-pane glass

IS – Insect Screen – a cover added to the outside of your window to prevent insects from flying in when your window is open

KWH – Kilowatt-Hour – a unit of measurement for energy, a common billing unit for electrical companies

IR – Infrared – rays of light that exist below the visible light spectrum that can be sensed as heat

Low E – Low Emission Glass – a coating on glass that reduces transmission of light through the glass and increases reflectivity

LSG – Light-to-solar-gain Ratio – a number that tells you the efficiency of different glass types for letting light but not heat through, a higher number means more light is transmitted without adding more heat

LVL – Laminated Veneer Lumber – a type of engineered wood product that combines multiple layers of thin wood together using adhesive materials, less prone to shrinking or warping

NFRC – National Fenestration Rating Council – an organization that has standards, ratings, and testing procedures for windows, doors, and skylights, read this to see one of their rating labels

OB – Obscured Glass – glass that has made more opaque, making it harder to see through, usually used for bathrooms, also known as privacy glass

OITC – Outdoor/Indoor Transmission Class – a number that tells you how much low-frequency sound will pass through a windows, doors, and walls, these low frequency sounds resemble cars and highway hum, a higher number indicates better sound insulation

OPG – Opening

OX / XO – used to denote opening direction of sliding windows. X is the operating side, where O is stationary

OW – Opening Window – a window that is meant to be opened

OM – Outside Measurement – the measurement of your window opening taken from the inside, as measured 6 inches away from the corners and at the center

PG – Performance Grade – a number rating from the NAFS that indicates how much your window can withstand harsh weather, a higher number indicates that it can withstand more load

PW – Pivot Window – a window that opens with a hinge on one side, also known as a casement window

PVB – Polyvinyl Butyral – a clear plastic resin that is used to glue together two panes of glass, used in impact resistant windows, read more about the material here

PVC – Polyvinyl Chloride AKA Vinyl – a strong plastic material used for many things, the most common material for window frames

ROI – Return On Investment – a measure of how much you spend versus how much money you get back, a higher number indicates that the money you spent was worth it, here’s how you calculate ROI

RS – Roller Shutter – a type of shutter that rolls down to compartmentalize a specific space, great for sound insulation or stopping fires, also called security shutters

SC – Shading Coefficient – a measure of a window’s ability to transmit heat, a number between 0 and 1, a lower number is better

SD – Sliding Door

SDL – Simulated Divided Lite – a window that consists of a large pane of glass with grids attached onto the surface, will look like an ADL

SFI – Sustainable Forest Initiative – an organization in the United States and Canada that focuses on sustainability by coming up with standards for conservation, community, and education

SH – Single Hung – a window with only one movable sash

SHGC – Solar Heat Gain Coefficient – the amount of heat that goes through a window, door, or skylight, a lower number is better

SO – Sash Opening

STC – Sound Transmission Class – a rating of how much sound a material blocks, a high rating indicates better sound reduction

SW – Sliding Window

U-Factor – Measures how much heat a window transfers, denoted as a number from 0 to 1, a lower U-factor means better insulation

USGBC – U.S. Green Building Council

UV – Ultraviolet – shorter wavelengths than visible light that can contribute to skin cancer

VP – Vertical Pivot – a casement window with a hinge in the center of the frame instead of on a single side

VS – Vertical Sliding

VT – Visible Transmittance – a measure of the visible light spectrum that goes through a window, door, or skylight, a higher number indicates more natural light will go through

WDMA – Window and Door Manufacturers Association – an association of people that promotes the use of higher performance doors, windows, and skylights, also comes up with standards, certification, and education for windows and doors

WF – Wood Frame

WOCD – Window Opening Control Device – a device that reduces falls, can limit the opening of a window, read more about it here

WS – Window Sill

Why Is Understanding Window Acronyms Important?

Being able to understand all of these window acronyms and words gives you a much better overview of window labels when you see them.

When your contractor talks about their AAMA certified windows, you now know what that means.

You’ll also see these acronyms on estimates, quotes, and drawings to depict your project.

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