| 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 |
