Autodesk 24000-000000-9860 - Revit Architecture - PC User Manual page 1162

Parameter
Voltage Loss/Gain Factor
Ballast Loss Factor
Lamp Tilt Loss Factor
Surface Deprecation Factor
Lamp Lumen Deprecation
Luminaire Dirt Deprecation
Total Light Loss Factor
Defining the Initial Intensity
When defining a lighting fixture, you can specify the initial intensity of its light source. The initial intensity
is a measure of how much light is produced by the light source in ideal conditions. (The actual light emitted
by a light source may be reduced by light loss factors. See
1124 | Chapter 17 Rendering
Description
gained due to temperature changes. Values greater than 1.0 indicate an
increase in light. Values less than 1.0 indicate a loss of light.
A measure of the amount of light lost or gained due to fluctuations in voltage
delivered to the light source. Valid values are between 0 and 2. A value of
1.0 indicates that no light is lost or gained due to voltage changes. Values
greater than 1.0 indicate an increase in light. Values less than 1.0 indicate
a loss of light.
Lamps and ballasts experience losses when operating together as a system.
The Ballast Loss Factor is the percentage of a lamp's initial rated lumens
that is produced by a given ballast. Valid values are between 0 and 1. For
example, a value of 0.95 indicates that the ballast produces 95% of its initial
lumens and loses 5%.
For metal halide lamps, a measure of the amount of light lost due to the
position of the lamp. A decrease in light occurs when the angle of the lamp
shifts the cold spot of the bulb. Values less than 1.0 indicate a loss of light.
A measure of the amount of light lost due to deterioration of the surfaces
of the lighting fixture as it ages. For example, blemishes and discolored
shielding materials change the amount of light emitted. Values less than
1.0 indicate a loss of light.
As a lamp ages, it produces decreasing amounts of light on a predictable
curve. A typical strategy is to use an average Lamp Lumen Depreciation
(LLD) value at 40% of its life. Valid values are between 0 and 1. For example,
a compact fluorescent has an LLD factor of 0.85, indicating an average
output at 85% of its initial lumens, losing an average of 15% over its life as
the lamp ages.
A measure of the amount of light lost due to environmental dirt and dust
that is trapped by the lighting fixture. Valid values are between 0 and 1.
For example, a value of 0.9 indicates that the fixture produces 90% of its
initial lumens and loses 10% due to trapped dust and dirt.
A measure of the amount of light produced by a lamp, taking into account
various environmental factors that obscure or reduce the emitted light.
When the Method is Simple, use the slider or text box to specify a value.
When the Method is Advanced, this parameter displays a read-only value,
which is calculated by multiplying the values of the other parameters. Valid
values are between 0 (total light loss) and 4 (light gain up to 400%). A value
of 1 indicates no light loss (100% of initial light intensity).
Light Loss Factor Parameters on page 1123.)