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Replacement Window Terms

Fiberglass Window Terms

Argon and Krypton Gas

Used to fill the air space between panels of glass, this odorless and colorless gas acts to resist heat transfer through the insulating glass unit. It works within the low emissivity (low-E) coating on the glass to produce better U-Values. Krypton gas is another inert gas that is a more effective insulator; however it is more expensive.


How windows are arranged in terms of proportion and design.


Window glass.

Double Glazing

When two panes of glass are set into a frame and are separated by an insulating air space. When This is referred to as Triple Glazing when three panes of glass are used.

Low-Emissivity Glass (Low-E Glass)

A coating on glass that reduces the amount of radiant heat and UV rays that passes through the glass.


The way glass fibers and resins are joined together to form a window or door frame.

Single Hung

A window where only the bottom sash can be opened and closed. The top of the window cannot be moved.


The vertical parts of a window sash.


This is a window placed above a door or another window. It is usually smaller in size.


Used to rate how well a material such as insulation resists the flow of heat through it. The higher an R-value is, the more heat loss it resists, and therefore the more energy efficient it is.


A rating of energy efficiency. U-values rate how much the heat the window allows to pass through it.

Solar Heat Gain Coeffecient (SHGC)

This is the rate at which heat is transfered (measured either by loss or gain) across the fiberglass window.

With all this knowledge of Fiberglass Replacement Window terms, you are more than ready to speak to a fiberglass window installer. Just fill out a request for a no-obligation window quote today and we'll have someone contact you to answer any questions you may have.