These variables are measured
in accordance with the EN 410-Standard. All measurements are made
at 0° profile angle. It should be noted that most of these variables
(and their standards) are intended as glazing properties. The measurements
are carried out at normal incidence, G-values calculated in accordance
with prEN 13 363-1.
Specifically for the solar transmittance, values for different angles
can not easily be extrapolated and are not yet documented.
As front and back of the Serge 2165 fabric differ, values are indicated
for both sides, as two different fabrics in the database.
Solar Transmittance Ts.
The percentage of energy in the solar spectrum, ultraviolet, visible,
and near-infrared energy, 300 to 4,000 nanometers, that is directly
transmitted through the fabric. Values vary between 2 for a dark Serge
2165 and 29 for a pale Top 2115.
Solar Reflectance Rs.
The percentage of energy in the solar spectrum, ultraviolet, visible,
and near-infrared energy, 300 to 4,000 nanometers, that is reflected
by the fabric. Values vary between 11 for a dark Serge 2165 and 63
for a white one.
Solar Absorptance As.
The percentage of energy in the solar spectrum, ultraviolet, visible,
and near-infrared energy, 300 to 4,000 nanometers, that is absorbed.
Solar Absorptance is given as :
As = 100 - Ts + Rs
Openness factor O-F.
indicates the percentage of perforation in the structure of the fabric.
Values vary between 2 for a Serge 2165 fabric and 16 for Top 2115.
Visible Light Transmittance Tv.
Tv indicates the percentage of light passing through the glass, for
the frequencies perceived by the human eye. Values vary between 3
for a dark Serge 2165 and 26 for a pale Top 2115.Shading Coefficient
SC.
A measure of the heat gain through glass from solar radiation. Specifically,
the shading coefficient is the ratio between the solar heat gain for
a particular type of glass and that of double-strength clear glass.
The lower the shading coefficient, the lower the solar heat gain.
(You can observe shading coëfficiënts to be lower for fabrics
used outside...).
Applied to Helioscreen fabrics the shading coëfficient was determined
for a combination of glass and fabric. 4 different kinds of glass
were considered for each fabric:
1 -Single 6mm clear glass.
2 -Single 6mm heat absorbing glass.
3 -Double 6+6 mm clear glass.
4 -Double 6+6 mm heat absorbing glass. As they are measured in combination
with a glass surface, values differ when placing the fabric either
at the interior or exterior. Therefor a double series of data is available
for our exterior fabrics.
The lowest shading coëfficient for single 6mm clear glass(and
thus best shielding against heat gain) is reached for a dark Serge
2165 with a value of 11 when used on the outside.
Highest shading coëfficient (same glass) proved to be for Top
2115, with values up to 78 percent.
UV transmittance TUV.
TUV indicates the percentage of ultraviolet radiation that passes
through. Ultraviolet should be accounted for in spaces where artwork
is kept. For Helioscreen fabrics this value ranges between 2 for a
dark Serge 2165 and 18 for a pale Top 2115.
REFERENCES
ASHRAE, American Society of Heating, Refrigerating and Airconditioning
Engineers
http://www.ashrae.org
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