The Add Actuator dialog is accessed by clicking on the Add actuator link in the Info panel of the Edit Script dialog when editing an EMS script. With the Add Actuator dialog open you can select from a list of actuators based on the actual model.
At the point the dialog is opened DesignBuilder asks you if you would like to update the list of available actuators by automatically running a preliminary simulation to generate an edd file with a list of all available actuators for the current model. If you agree to this there will be a delay (of several minutes for larger models) while EnergyPlus is run to generate the .edd and .rdd files.
Select the one of the actuators listed in the right hand data panel by either a) double-clicking on the required actuator, or b) by single-clicking on the required actuator and then clicking on the Select 
icon.
When you press the OK button Erl code for the actuator is inserted into the script at the cursor position.
You can get DesignBuilder to set up a DB Erl loop to include script to generate multiple actuators by checking the Add loop checkbox. For more information about setting up DB Erl loops see the Add Sensor dialog help.
Enter the name of the actuator to be used in Erl script.
When an actuator is selected from the list, the actuator Name is automatically set to be the name of the actuator, but with all illegal characters such as spaces replaced with "_". If the Add loop option is activated then one of the following DB Erl keywords is appended to the name, preceded by the "_" character:
Enter a specific object name such as a zone or surface IDF name, or enter "*" to indicate all relevant objects.
When the Add loop option is selected and an appropriate actuator is selected from the list, the actuator Object IDF name is automatically set to be one of:
When an actuator is selected from the list, the actuator Data type field is automatically set. This is the same as the name of the actuator listed.