| Lighting control type
|
Contains controls used to set the type of overhead
electric lighting control. All reference points specified later are assumed to
have the type of control selected from the following:
- Continuous — When
selected, the overhead lights dim continuously and linearly from (maximum
electric power, maximum light output) to (minimum electric power, minimum light
output) as the daylight illuminance increases. The lights stay on at the
minimum point with further increase in the daylight illuminance.
- Stepped — When
selected, the electric power input and light output vary in discrete, equally
spaced steps. The number of steps is set with the Number of stepped control
steps control which is enabled when the Stepped lighting control type is
selected. – For example, if the number of controlled steps = 3 and the
Illuminance setpoint = 600, then the following table shows the fraction of the
lights that are on versus daylight illuminance.
| Daylight illuminance
|
Fraction of lights that are on
|
| 0–200
|
1.0
|
| 200–400
|
2/3
|
| 400–600
|
1/3
|
| 600 and above
|
0.0
|
- Continuous/off —
When selected, the overhead lights dim continuously and linearly from (maximum
electric power, maximum light output) to (minimum electric power, minimum light
output) as the daylight illuminance increases. The lights switch off completely
when the minimum dimming point is reached.
|
| Min. input power fraction for continuous dimming
control
|
For the Continuous lighting control type, sets the
lowest power the lighting system can dim down to, expressed as a fraction of
maximum input power. For the Continuous/off lighting control type, sets the
power fraction reached just before the lights switch off completely.
|
| Min. light output fraction for continuous dimming
control
|
For the Continuous lighting control type, sets the
lowest lighting output the lighting system can dim down to, expressed as a
fraction of maximum light output. This is the fractional light output that the
system produces at minimum input power. For the Continuous/off lighting control
type, sets the power fraction reached just before the lights switch off
completely.
|
| Number of stepped control steps
|
For the Stepped lighting control type, sets the
number of steps, excluding off, in a stepped lighting control system. The
number of stepped controls is required and must be greater than zero. The
control steps are assumed to be equally spaced.
|
| Reset probability
|
For the Stepped lighting control type, a reset
probability may be used if the stepped lighting control manually operated
(simple one-step on/off system). The value entered here is the probability the
occupants of the selected room will set the electric lights to the correct
level to obtain the required illuminance. The rest of the time the lights are
assumed to be set one step too high.
– For example, in an on/off lighting system (Number
of stepped control steps = 1) with a set point of 600 lux and 0.7 reset
probability, when daylighting exceeds 600 lux, the electric lights are off 70%
of the time and on 30% of the time.
|
| Glare calculation azimuth angle
|
Sets the view direction for calculating glare.
Daylight glare from a window depends on occupant view direction. It is highest
when you look directly at a window and decreases as you look away from a
window. The Glare calculation azimuth angle is the angle, measured clockwise in
the horizontal plane, between the room y-axis and the occupant view direction.
|
| Max. allowable discomfort glare index
|
Used to enter a glare discomfort index that when
exceeded, activates the shading devices on the windows in the selected room.
Values appropriate for the allowable discomfort glare index vary depending upon
the room type and room activity type. The following table provides some
recommended values.
| Activity or room type
|
Max. allowable discomfort glare index
|
| Art galleries
|
16
|
| Factories – Rough work
|
28
|
| Factories – Engine assembly
|
26
|
| Factories – Fine assembly
|
24
|
| Factories – Instrument assembly
|
22
|
| Hospital wards
|
18
|
| Laboratories
|
22
|
| Museums
|
20
|
| Offices
|
22
|
| School classrooms
|
20
|
|
| Reference point 1
|
When on, horizontal daylighting illuminance will be
calculated for the selected room based on the values entered for Reference
point 1. It is assumed that the photocells that control the overhead electric
lighting respond to the light levels at the location of the first reference
point.
- Zone controlled
fraction — Sets the fraction of the room’s floor area whose electric lighting
is controlled by the daylight illuminance at Reference point 1. If there is
only one reference point then a fraction = 1.0 is assumed to have no lighting
control.
- Illuminance
setpoint — Sets the desired lighting level (in lux) at Reference point 1. This
is the lighting level produced at reference point 1 at night if the overhead
electric lighting are operating at full input power. Recommended values depend
on the type of activity, which they may be found, for example, in the Lighting
Handbook of the Illuminating Engineering Society of North America. A typical
value for general office work (excluding computer terminals) is 500 lux.
|
| Reference point 2
|
Enabled if the selected room is to be divided into
two independently controlled lighting zones. When on (and Reference point 1 is
also on), horizontal daylighting illuminance will be calculated for the
selected room based on the values entered for Reference points 1 and 2. It is
assumed that the photocells that control the overhead electric lighting respond
to the light levels at the locations of the two reference points independently.
- Zone controlled
fraction — Sets the fraction of the room’s floor area whose electric lighting
is controlled by the daylight illuminance at Reference point 2. If there are
two reference specifies, a fraction = 1.0 ([Zone controlled fraction set for
Reference point 1] + [Zone controlled fraction set for Reference point 2]) is
assumed to have no lighting control.
- Illuminance
setpoint — Sets the desired lighting level (in lux) at Reference point 2. This
is the lighting level produced at reference point 2 at night if the overhead
electric lighting are operating at full input power. Recommended values depend
on the type of activity, which they may be found, for example, in the Lighting
Handbook of the Illuminating Engineering Society of North America. A typical
value for general office work (excluding computer terminals) is 500 lux.
|
