U-Value
U-value measures the heat transfer that occurs through the inside and outside surfaces of glass. The U-value is a function of temperature and is expressed in BTUs (sec definition) per square foot per hour per degree Fahrenheit (BTU / sq. ft. / hr. / F°). Better insulation systems, including window film, have lower U-values.

Ultraviolet (UV)
The damaging portion of the solar energy spectrum that causes fading and deterioration to fabrics, furniture and furnishings. UV rays also age skin and cause skin cancer.

Ultraviolet (UV) Inhibitors
Chemical and material elements added to products such as window film and lotions to block and / or filter out varying amounts of harmful UV rays.

Ultraviolet (UV) Transmittance
The ratio of the amount of total ultraviolet solar energy that passes through glass compared to the amount of total UV solar energy that falls on the glass. (Use of window film can affect this.)

Visible Light Reflectance
The percentage of total visible light that is reflected by glass and that can be seen.

Visible Light Transmittance
The ratio (percentage) of the total amount of visible solar energy (usually called light) that passes through glass compared to the total amount of visible solar energy that falls on the glass. (Use of window film can affect this.)

Wet Glaze
The application of silicone sealant or similar liquid-state material around the perimeter of the glass, e.g., a bead of silicone mastic used to bond the film to the glass to the window frame.

Wired Glass
Wired glass is produced on the same equipment as figured / pattered glass. A welded wire netting or parallel wires are introduced into the molten glass just before entering the rolls to embed the wire into the glass. Patterned wired glass has a pattern on one or both sides, and is sometimes called "rough" wired glass. Polished wire glass is produced by grinding and polishing rolled wired glass blanks. Tinted / heat absorbing wired glass is available only as an import. The heat absorbing characteristic in conjunction with the normally poor cut edges and the wire netting can cause a high rate of breakage from thermal stress, especially in non-vertical applications. The major uses of wired glass are in institutional buildings and fire rated windows and doors. All wires must be completely embedded in the glass. Some misalignment of the wires may be noticeable, but this is not considered cause for rejection. Wired glass cannot be tempered.