TechnicalTerms
| VLT : | Visible Light Transmission The percent of total visible light that passes through a glazing system |
| VLR : | Visible Light Reflectance The percent of total visible light that is reflected through a glazing system |
| TST : | Total Solar Transmittance The percent of incident solar radiation that directly passes through a glazing system |
| TSR : | Total Solar Reflectance The percent of incident solar radiation that is reflected by a glazing system |
| TSA : | Total Solar Absorption The percent of incident solar radiation that is absorbed by a glazing sysytem |
| SC : | Shading Coefficient The ratio of solar heat gain passing through a glazing system to the solar heat gain that occurs under the same conditions if the window was made of clear, unshaded double strength window glass. The lower the number, the better solar shading qualities of the glazing system. |
| SHGC : | Solar Heat Gain Coefficient The fraction of the heat from the sun that enters through a window. The lower the number, the less solar heat it transmits |
| E : | Emissivity A measure of surface's ability to absorb or reflect far-infrared radiation. The lower the emissivity, the higher the far-infrared rejection. The lower the emissivity rating, the better the insulating qualities of the glazing system |
| UVR : | Ultraviolet (UV) radiation Rejection The percent of total ultraviolet light that is prevented from passing through a glazing system |
| TSER : | Total
Solar Energy Rejection The percent of total solar energy (heat) rejected by a glazing system. It equals the solar reflectance plus the part of solar absorption which is re-radiated ourward. |
| Sputtered : | The
basic sputtering process involves a large vacuum chamber and an inert (or reactive) gas
atmosphere as well as electrical energy. The electrical energy imparts a negative charge
to the atoms or molecules of the gas. The vacuum pressure, which is extremely low
compared to normal atmospheric pressure, allows the negatively charged particles to move
freely around the chamber at high velocity. When those charged particles strike a
cathode, which is the metal that is going to be applied to the film, atoms of the metal
(or metallic oxide) are dislodged from the cathode at a high velocity. These atoms strike
the film substrate, creating a thin layer of metallic oxide. Sputtered films have excellent solar heat control properties like those that are produced by the metalizing process. Sputtering is a versatile process as several layers of different metals can be applied to a single piece of film (metal on metal layering), resulting in unique colors and higher levels of selective transmissions. |
| Metalized : | In simplest terms, metalizing is a process whereby a
metal (almost exclusively aluminum) is deposited as a layer (coating) onto clear polyester
film, to which another layer of polyester film is laminated. These products are excellent
solar control films capable of rejecting over 80% of all solar radiation. As the vacuum
metalizing process can be controlled, the thickness of the layer of aluminum may be
deposited to precise tolerances. This results in solar control films that have varying
levels of visible light transmission. These levels of visible light transmission affect
the performance of the film. In general, lower the visible light transmission, the higher
the solar heat rejection. Combining the aluminum substrate layer with a dyed film layer, instead of a clear layer, can produce various colored versions of this film (bronze, gray, etc.). They in turn may have various levels of light transmissions and solar control properties, but a uniform color appearance. |
| References : | 1. IWFA Flat Glass Education
Guide 2. http://resourcecenter.pnl.gov/cocoon/morf/ResourceCenter/article//93 Article #93, Building Energy Codes Resource Center |