Automatic control functions exist for the lighting which will allow you to control how much lighting gain there will be in a zone based on the calculated illuminance levels at each hour. A lighting function can reference the applied zone, or it can use another zone in the model as the control. To use a lighting function you will need to have calculated a daylight factor in the zone for which the lighting function will be referencing (the 'control zone'). The daylight factor is defined as the average diffuse illuminance on the working plane within the zone as a percentage of the diffuse illuminance on a horizontal plane outside of the building. Daylight factors can be calculated using the daylight facility which has been built into the 3D Modeller (see the Tas Daylight user-guide for more details), or you can use the Daylight Factor Calculator in the Utilities folder to calculate daylight factors using an approach based on the simplified BRE method.
Three different control types are available, they are called 'Manual Control', 'Photocell Control', and 'No Control'. There are two calculation methods to choose from, you can select either 'Gain Method' or 'Efficacy Method'. These will be described below, and on the lighting pages to follow.
On the internal conditions Gains table, click on 'Lighting Gain' and then set the Type value to 'Function' on the Profile dialog. This will open the Lighting Control Function window, which is where you will set the control type, calculation method, and lighting parameters. After selecting a control type and calculation method, the relevant mnemonic code will be visible in the function description, which can be found below the Parameters section.
So each lighting function will have its own mnemonic code, depending on control type and calculation method - there are five function definitions to choose from. The codes for the lighting functions are given below (the function definition is described in a new topic, click on the link to go to that topic):
When manual control is paired with the gain method, the lighting gain in the zone will be determined by the mlclg function definition. When manual control is paired with the efficacy method, the mlcle function call will be made instead. So if the fifth letter in the mnemonic is a 'g' then it will be using the gain calculation method, and if the last letter is an 'e' then it will be using the efficacy method. To use the plclg function, you should select the photocell control type and set the calculation method to 'Gain Method'. You can use plcle by using photocell control and choosing the efficacy method. Finally, the nlcle function will be used when you select efficacy and then set the control type to 'No Control'. This information has been summarised in the table below:
|
Gain Method |
Efficacy Method |
Manual Control |
mlclg |
mlcle |
Photocell Control |
plclg |
plcle |
No Control |
No available function |
nlcle |
The Lighting Control Function dialog will give you the chance to set values for various parameters, for example you will be able to set the minimum room illuminance that will be used to determine when the lighting gain is at its maximum. The two main sections on the dialog are described as 1. Control Logic, and 2. Parameters. The SI (metric) measurement units are given in the following table.
Lighting Parameter |
Unit of Measurement |
Illuminance |
lx |
Lighting gain |
W/m^2 |
Efficiency |
W/m^2.100lx |
Area cut-off |
m^2 |
Efficacy |
lm/W |
Parasitic power |
W/m^2 |
For the US Customary (I-P) measurement system, illuminance will be given in foot-candles (fc), gains will be given in W/ft^2, and efficiencies will be given in W/ft^2/100fc. To change between measurement systems, click on the Settings button on the Tas Manager and then click on the Measurement System down-arrow on the Localisation tab.
Control Logic
Control Type
Manual Control - sets the function definition to mlclg or mlcle, depending on which calculation method you have chosen to use. Selecting 'Gain Method' on the 'Calculation Method' drop-down list will set the manual control function to mlclg, whilst 'Efficacy Method' will set the function to mlcle.
Photocell Control - sets the function definition to plclg or plcle, depending on which of the two calculation methods you have chosen. Select 'Gain Method' to set the photocell control function to plclg, or to use plcle instead, set the control type to 'Efficacy Method'.
No Control (only available when you select the efficacy calculation method) - sets the function definition to nlcle.
Calculation Method
Gain Method - input parameters will be based on lighting gains (you will be asked to input the maximum and minimum gains in the zone), or alternatively the lighting gain in the zone will be back-calculated from an efficiency value given in W/m^2/100lx, which you will have to input along with a minimum percentage gain.
Efficacy Method - input parameters will be based on an efficacy value in lm/W and a minimum percentage gain, so the lighting gain will not drop below this percentage of the gain required to fully illuminate the zone to the target illuminance level.
Parameters (available when you select Manual Control along with the Gain Method for the calculation of lighting gain)
Control Zone
Applied Zone - the lighting gain will be determined by the illuminance level within the zone to which the internal condition is applied, in accordance with the function definition.
<Zone Name> - the lighting gain in the applied zone (the zone to which the internal condition will be applied) will be determined by the illuminance level in this zone, in accordance with the function definition.
Min Illuminance - at or below the minimum illuminance level the lighting gain will be at its maximum value.
Target Illuminance - the illuminance level in the zone at which the lighting gain will be at its minimum value.
Enter Gains (radio-button)
Max Gain - the maximum lighting gain within the zone, as determined by the minimum illuminance level. This value used to determine the lighting gain within the zone when 'Calculate Gains by Efficiency' is selected, and the natural room illuminance exceeds the target room illuminance.
Min Gain - the minimum lighting gain within the zone, as determined by the target room illuminance.
Calculate Gains by Efficiency (radio-button)
Efficiency - the lighting efficiency measured in W/m^2.100lx.
Minimum Percentage - the percentage of the maximum lighting gain which will be used when the natural room illuminance exceeds the target room illuminance.
Area Cut-Off - zones with an area greater than this value will use the maximum lighting gain. If you don't want to introduce an area cut-off in your lighting control strategy, set this value to '999' or higher, depending on the size of the zone.
Parameters (available when you select Manual Control along with the Efficacy Method for the calculation of lighting gain)
Control Zone
Applied Zone - the lighting gain will be determined by the illuminance level within the zone to which the internal condition is applied, in accordance with the function definition.
<Zone Name> - the lighting gain in the applied zone (this is the zone to which the internal condition has been applied) will be determined by the illuminance level in this zone, in accordance with the function definition.
Target Illuminance - the natural illuminance level in the zone at which the lighting gain will be at its minimum value.
Efficacy - the lighting efficacy is a measure of efficiency which has been expressed as a ratio of luminous flux to power, and so the units of measurement will be lumens per Watt (lm/W). This value will be used to back-calculate the maximum lighting gain in the zone.
Area Cut-Off - zones with an area greater than this value will always use the maximum lighting gain. If you don't want to introduce an area cut-off in your lighting control strategy, set this value to '999' or higher, depending on the size of the zone.
PIR Factor - the calculated gain will be multiplied by a factor between 0-1 in order to represent the effect of automatic presence detection.
Minimum Percentage Gain - the lighting gain in the zone won't go below this percentage of the maximum lighting gain, which is the gain required to fully illuminate the zone to the target illuminance.
Display Lighting - during hours with sensible occupancy gain a display lighting gain will be added.
Parameters (available when you select Photocell Control along with the Gain Method for the calculation of lighting gain)
The input parameters are the same as when you select manual control and choose the gain method of calculation, except there is no area cut-off value and there is an additional parameter called 'unoccupied gain' which is used to determine the lighting gain outside of occupied hours.
Unoccupied Gain - during hours with no sensible occupancy gain the lighting gain will be determined by this value.
Parameters (available when you select Photocell Control along with the Efficacy Method for the calculation of lighting gain)
The input parameters are largely the same as when you select manual control and choose the efficacy method, except there is no area cut-off value, and there are two additional values needed to complete the function definition - these are 'parasitic power' and 'timer clock'.
Parasitic Power - during all hours a parasitic power gain will be added. The parasitic power represents the amount of energy consumed by the photocell sensor.
Typical values:
Digital Addressable Systems - 1W/m^2.
Standalone Sensors - 0.3W/m^2.
Timer Clock - a timer clock will determine when the photocell sensor will be turned on. Place a tick in this checkbox to turn on the photocell sensor during the occupied period, i.e. for those hours where a sensible occupancy gain is detected.
Parameters (available when you select the Efficacy Method for the calculation of lighting gain and set the Control Type to No Control)
The same input parameters as manual control and efficacy, except you will not need to specify values for area cut-off or minimum percentage gain.