TERMS RELATED TO WINDOW FILM
Dual Reflective Film Dual reflective window films offer privacy while maintaining energy efficiency. The film on the outside is highly reflective creating a mirror image of the surrounding area. From the inside the film still blocks the heat but you can still see the outside through the window.
Emissivity (E) The ability of the surface to reflect infrared energy. For window film, this means how much heat it will re-radiate back into a room. Low E glass and films have low emissivity, which means they reflect a lot of heat back into the room and is the desired effect in the winter time
Glare Reduction The percentage by which visible light is reduced by the addition of window film without obstructing the view of the outside
Infrared Rejection The amount of infrared (IR) energy that is blocked by the film, either by reflecting or absorbing. This value is for the whole IR region of the solar spectrum, roughly 780nm up to 2500nm
Reflective glass lets optimal light into your space, but also reduces glare from the sun, which eliminates the need for blinds and other window coverings. And when combined with solar-controlling low-e coating, this glass can reflect incoming radiant heat energy to keep your HVAC costs low
Shading Coefficient (S) The ratio of heat passing through a filmed window to heat passing through clear unfilmed glass. The lower the shading coefficient number, the better the shading qualities of the installed window film.
Solar Heat Gain Coefficient (SHGC Similar to the shading coefficient, except this value also takes into account energy that is re-radiated back into the room from the glass heating up due to increased absorption. The lower the SHGC, the better the solar control properties of the film.
Total Solar Energy Absorptance The amount of total solar energy that is absorbed into the glass. This heats up the glass, making it hotter to the touch, and re-radiates a small amount of heat back into the building or automobile. The majority of absorbed energy is kept out of the car though.
Total Solar Energy All the energy in the solar spectrum that reaches us on the earth’s surface. This includes UVA and B, visible light, and infrared energy up to roughly 2500nm. Heat often refers to the total solar energy.
Total Solar Energy Rejected (TSER) The total amount of solar energy that is kept out of the building or automobile. Commonly referred to as heat rejection.
Total Solar Reflectance The amount of total solar energy that is reflected off of the glass and directed back outside. This energy does not come into the building or automobile.
Total Solar Transmittance The amount of total solar energy that passes through the glass
Visible Light – Reflected Interior The amount of visible light that is reflected off the interior surface of the window. This is seen when standing inside the building looking out. A higher reflectance value means the window looks more like a mirror from the inside.
Visible Light – Reflected Exterior The amount of visible light that is reflected off the exterior surface of the window. This is seen when standing outside the building or automobile. A higher reflectance value means the window looks more like a mirror from the outside.
Visible Light Transmittance (VLT) The amount of visible light that passes through the installed window film into a building or automobile. This is how light or dark the film is. As an example, limousines usually tint their windows with films that have a VLT of 5%.
ADDITIONAL WINDOW TINTING TERMS
Ambient The immediate surroundings or encompassing atmosphere.
Attachment Systems Chemical or mechanical restraint systems that improve the performance of safety & security window film during powerful winds, blasts, and smash-and-grab break-ins.
BTU (British Thermal Unit) A traditional unit of heat, the British Thermal Unit (BTU) is the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit (1 BTU = 252 Calories).
Clear Glass Clear glass is made of silica sand with added alkaline salts such as lime potash and soda. It is colorless, has a visible light transmittance ranging from 75% to 92%, depending upon thickness, and constitutes the bulk of the flat glass that is used.
Clear Dry Adhesive (CDA) A mounting adhesive that uses water to activate and form a chemical bond between the glass and film, so the film adheres to the glass during installation. Clear dry adhesive offers a strong bond, film clarity, and longevity.
Daylight Installation The process of applying window film to a piece of glass from edge-to-edge. The small untreated area of glass that remains is referred to as a “daylight gap”.
Figured/Patterned Glass Figured or patterned glass is produced domestically by the continuous pour process in thicknesses of 1/8-inch to 7/32-inch. A pattern etched on one or both of the rollers is reproduced on the glass. Colors, while available, are extremely limited. Figured glass is often called “obscure” or “decorative” glass. It has powerful light-diffusing properties, but it is not transparent. The degree of diffusion achieved depends on the pattern and whether the pattern is on one or both sides. Some patterns cannot be tempered for safety glazing use because of their depth.
Glass Edge Strength Glass is made to withstand from between 3000 to 5000 psi (210 to 350 kg/cm) of edge stress. When edge stress exceeds edge strength, breakage occurs. Edge strength is dependent on glass size, thickness, how it is cut, and a glazier’s treatment of the edge. A straight clean edge is the strongest. If edges are damaged, they can reduce edge strength by up to 50%.
Glazing Glazing, which derives from the Middle English for ‘glass’, is a part of a wall or window, made of glass. Glazing also describes the work done by a professional “glazier”. Glazing is also less commonly used to describe the insertion of ophthalmic lenses into an eyeglass frame.
Infrared Light Infrared, sometimes called infrared light, is electromagnetic radiation with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from the nominal red edge of the visible spectrum around 700 nanometers, to 1 millimeter
Insulated Glass Double insulated glass consists of two panes of glass that enclose a hermetically sealed air space. The panes are held apart by a spacer around the entire perimeter. The spacer contains a desiccant, which is a moisture absorbent material that serves to keep the enclosed air free of visible moisture.
Laminated Glass Laminated glass is a type of safety glass consisting of two or more layers of glass held in place by an interlayer of clear or tinted polyvinyl butyl (PVB). The application of heat and pressure bonds the glass and plastic interlayer into one unit. When laminated glass is fractured, the particles of glass tend to adhere to the plastic, offering protection against flying or falling particles. Some combinations of glass and plastic thicknesses do qualify as safety glazing materials under the criteria of the American National Standards Institute (ANSI) Z97.1-1984 and Federal Standard 16 CFR 1201.
Low-Emissivity (Low-E) Low-Emissivity, or Low-E, refers to a coating on glass or window film that reduces heat loss through the window film. The lower the emissivity rating, the better the insulation characteristic of the glazing system in regard to heat loss.
Luminous Efficacy The ratio of visible light transmission (VLT) to solar heat transmission for a window. A higher luminous efficacy means the film has high heat rejection given its VLT.
Mechanical Attachment System This method is used for enhanced glass retention, anchoring 8 Mil or thicker safety & security film to the window frame with a metal batten system. The safety & security film is installed to the glass, overlapping the window frame by approximately 1-inch. A metal batten system is placed over the overlapped film and screwed into the existing window frame, securely attaching the window film to the frame. Depending on the type of glass retention needed, the mechanical system can be attached as a one-sided (top), two-sided, or four-sided installation.
Metallic Film Window film that uses either a sputtering or deposition process to deposit metals onto its surface to achieve the qualities and look of tinted film.
Metalized The process where metals are applied onto a clear, polyester film as an even layer. Different metals produce different hues and performance capabilities to meet consumers’ varying needs.
MIL The Unit of length for 1/1000 of an inch (.001-inch). It is used in expressing thickness of films, i.e., 1 MIL = 25 microns.
Reflective Glass Reflective glass is clear or tinted glass coated with a very thin layer of metal or metallic oxide.
Safety Film Safety film is composed of incredibly strong, optical-quality clear or metallized polyester, high-grade ultraviolet inhibitors, special laminating and mounting adhesives, and scratch-resistant coating. The product is retrofit to interior glass surfaces for glass breakage protection. When events such as natural disasters, vandalism, or bomb blasts cause glass to break, the film’s flexible construction and pressure-sensitive mounting adhesive help hold the shards together, keeping them from shattering. This reduces the potential for personal injury and property damage. Safety film is also referred to as anti-shatter film, glass fragment retention film, blast mitigation film, and Mylar.
Solar Energy Energy from the sun represented by visible light (glare), infrared radiation (heat), and ultraviolet radiation (fading and health hazards). Each energy form is differentiated by its wavelength
Tempered Glass Tempered glass is often used in applications where using standard glass could pose a potential danger. Tempered glass is stronger than standard glass and does not shatter into large shards when broken. This is important, because it can greatly minimize potential danger in the case of a break. Manufactured through a process of extreme heating and rapid cooling, tempered glass is much harder than normal glass.
In the case that tempered glass does break, it shatters into small pebbles that are void of dangerous, sharp edges. As tempered glass is considered to be much safer than normal glass, you may often here it referred to as safety glass or toughened glass. Tempered glass has a wide variety of uses that you’ll find just about everywhere. In fact, the shower doors in your bathroom or the side glass on a motor vehicle are examples of tempered glass.
Another benefit of tempered glass is the ability to stand up to moderate heat (470°F). The process that creates this strengthened glass also makes it heat-resistant. This makes tempered glass a great solution for a situation where there is a danger of the glass breaking due to impact or moderate heat. Tempered glass is often used for fireplace doors (not woodstoves), on masonry and prefabricated fireplaces. If tempered glass is exposed to higher temperatures, it gradually weakens the structure of the glass thus making it more susceptible to breakage. Tempered glass is not recommended in wood burning applications.
Thermal Stress When exposed to solar radiation all glass absorbs energy. Tinted glass absorbs more energy than clear glass. This occurs when there is a temperature differential between the center of the glass and its shaded edges. The ability of the glass to not break is determined by its edge strength.
Tinted/Heat Absorbing Glass Tinted or heat absorbing glass is produced by adding various colorants to the normal, clear glass batch to create a desired color. The four colors available by the float process are bronze, gray, green, and blue. Visible light transmittance will vary from 14% to 83%, depending upon color and thickness. The color density is a function of thickness and increases as the thickness increases. Visible light transmittance will also decrease as thickness increases.
Tinting reduces the solar transmittance of glass, has little effect upon solar reflectance, and thus increases solar absorption (heat). This explains why heat strengthening or tempering is sometimes required for the thicker tinted glasses. Adding a metallic coating also has the same effect on thinner glasses.
Transmissivity The amount of radiant energy (energy of electromagnetic waves) transmitted from a radiating object through the atmosphere to a target after reduction by atmospheric absorption and scattering.
U-Value The ability of heat to transfer through one square foot of window film for each degree Fahrenheit difference in temperature. The local climate or environment in which the window is located affects the level of heat transfer and the rate. In summer, heat transfers from the outdoor air to indoor air.
In winter, heat transfers from indoor air to outdoor air. The lower the U-value, the better insulating qualities of the installed window film so heat is kept inside in cold climates.
- Median: refers to the part of the U-factor/U-value chart that applies to “mild winter” conditions.
- Design: refers to the part of the U-factor/U-value chart that applies to “severe winter” conditions.
Ultraviolet Light (UV) The damaging portion of the solar energy spectrum that causes fading and deterioration to fabrics, furniture, and furnishings. Invisible, powerful wavelengths (shorter than light but longer than X-rays) emitted by the sun separated into three types, UV-A, UV-B, and UV-C. UV-B causes sunburn, and prolonged exposure can age skin and cause skin cancer. Window films block nearly 100% of ultraviolet light from passing through glass.
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 damaging UV rays.
Ultraviolet (UV) Transmittance The percent of ultraviolet light (UV) that is transmitted by the installed window film. The lower the number, the less UV light is transmitted.
Ultraviolet (UV) Rejection The amount of UV energy blocked by the film, either by reflecting or absorbing it. This energy does not enter the building or automobile. The higher the number, the more UV rays are blocked.
Visible Light Electromagnetic radiation at wavelengths that we can see. We perceive this visible light as colors ranging from red (longer wavelengths; ~700 nanometers) to violet (shorter wavelengths; ~400 nanometers).
Visible Light Absorptance (VLA) The percent of total visible light absorbed by the installed window film. The lower the number, the less visible light is absorbed.
Visible Light Reflectance (VLR) The percent of total visible light reflected by the installed window film. The lower the number, the less visible light is reflected. A higher VLR rating offers better glare control and films with higher ratings tend to be more reflective and/or darker.
Visual Acuity Visual acuity refers to the clarity of your vision. Some people believe that the application of window film distorts their outdoor view when they are indoors. But due to visual acuity, eyes adjust to the amount of light they are receiving, so even when film reduces views from the outside looking in, the same is not true for the reverse.
Wet Glaze The application of a silicone sealant or similar liquid-state material around the perimeter of the glass to secure the glass to a frame (e.g., a bead of silicone mastic used to bond the film to the glass to the window frame).