This option will set the automatic control function to MANUAL CONTROL and will be based on the EFFICACY calculation method.
To use this lighting function you will need to have calculated a DAYLIGHT FACTOR within the zone for which the lighting function will be referencing (the 'control zone').
To use the function, under the Control Logic area on the dialog, set the Control Type to "Manual Control" on the drop-down list. Then choose "Efficacy Method" from the Calculation Method drop-down options. Under the Parameters area, choose whether the applied zone will act as the control zone. The applied zone will be the zone to which the internal condition is applied. Otherwise you will need to specify which zone in the model will act as the control zone. If you select another zone from the drop-down list to be the control zone, its illuminance levels will determine when and how the lights will be operated within the applied zone.
The calculated lighting gains will be a function of the target room illuminance and the efficacy value in lm/W. You will need to input the illuminance level at which the lighting gain will be at its minimum value, this will be the target room illuminance. You will then input the efficacy value for the lighting. The efficacy will then be used to back-calculate the maximum lighting gain. You will also input a minimum percentage gain value. The minimum percentage gain is defined as the percentage of the maximum lighting gain that will be used when the natural room illuminance exceeds the target room illuminance.
The lights will operate as follows, in the first occupied hour the function will look to see what the illuminance level is, and if it is at or below the target room illuminance. If the illuminance level is at (or above) the target illuminance then the lighting gain will be set to the minimum value, and you will have already specified the percentage of the maximum lighting gain that will apply when the illuminance level is at or above the target room illuminance. Although you haven't entered a maximum lighting gain into the software, this value will be derived from the efficacy value. In the second occupied hour, the function will look to see if the illuminance level has changed. If the illuminance level is still at or above the target illuminance then the lighting gain will not be changed from the value that was used in the first hour, but the function will always look to see if the lighting gain needs to be updated at each hour. If the illuminance level has dropped below the target room illuminance, meaning that the room will have reduced access to daylight than it did during the previous hour, the lighting gain will be increased. The lighting gain will be increased linearly as illuminance levels decrease linearly, until the lighting gain has reached its maximum value.
The defining characteristic of the manual control function is this, during the occupied period, if the illuminance increases at any hour, the lighting gain will not be reduced. This is to model occupant behaviour consistent with turning lights on to give more light, but then not turning them off when more daylight becomes available.
If you need the lighting gain to reduce at hours when the illuminance level has increased, then you should select the photocell control method for your automatic lighting control function.
Example - mlcle,0,0.1,30,6.67,500,999,2.5
The function string begins with a '0', which indicates that the control zone is the applied zone.
The next number is '0.95', which means the lighting gain will be multiplied by a PIR factor of 0.95.
This is followed by the number '30', which represents the efficacy value in lm/W.
The next number is '6.67', giving the percentage of the maximum lighting gain that will apply when the illuminance level is at or above the target room illuminance.
The '500' value is the target room illuminance.
The '999' means that any zones with an area greater than 999m^2 will use the maximum lighting gain value during the occupied hours.
Finally, '2.5' is the display lighting value. During hours with sensible occupancy gain, a display lighting gain will be added.
Let's look at a worked example, based on this function string. Assume the zone area is smaller than the area cut-off value. Suppose the illuminance level in the first hour is 500lx, which is the target room illuminance. This means that the lighting gain will be at its minimum value. The minimum value will be determined by the minimum percentage gain value. So the lighting gain at hour 1 will be 6.67% of the maximum lighting gain. At hour 2, the illuminance then falls to 300lx, so the lighting gain will be increased linearly. At hour 3, the illuminance level increases to 400lx, and the lighting gain will not change from the value is was at during hour 2. At hour 4 the illuminance level has fallen to 200lx and so the lighting gain will increase to again to compensate. When the illuminance level is at the specified minimum, the lighting gain will have reached its maximum value. The lighting gain will not be reduced during the remaining occupied period. The PIR factor of 0.95 will be used as a multiplication factor to reduce the calculated gain to model automatic presence detection behaviour. Finally, the display lighting gain will be added.