One way of using ventilation is to enter an automatic control function. These functions are a way of controlling ventilation based on zone temperatures and outside temperature. Four basic modes of operation have been implemented and are described in the following sections, click on the link to go to the relevant topic:
To use a ventilation function, click on the word 'Ventilation' in the gains table and select 'Function' from the 'Type' drop down list on the Profile dialog. You will be able to manually enter the acronym and the parameters separated with commas into the 'Function' box or you can input the function parameters by selecting a function name on the Select Ventilation Control dialog to open the relevant Enter Parameters window.
You will also be able to set up an Hourly Function or a Yearly Function when deciding how the ventilation will operate. These were defined earlier on in the manual, to revisit the section click on this link to open the Editing Profiles topic.
It is possible to use both a factor and a schedule to modify the behaviour of the automatic control. The factor in the Ventilation profile is always multiplied with the ventilation value from the automatic control function.
When scheduling is used in conjunction with ventilation control, very complex systems can be created and simulated. The value from the schedule (either 0 or 1) is multiplied by the ventilation value from the ventilation function. This allows the mechanical ventilation to be automatically controlled, and available, at only certain times of day.
Each mode can be thought of as a number of rules. Each rule can then be thought of as a function, producing a signal, a value of 0 or 1, which indicates whether the ventilation should be on (1) or off (0). For example, the zone temperature rule can be represented by this graph.
The outside temperature cut-off rules as this graph.
During a simulation, the selected mode will calculate the appropriate signal value from each of its rules. The final ventilation value is simply the product of all of the signals. In this way a rule that specifies off, with a signal value of 0, will force the ventilation to off no matter what the other rules are returning. Likewise, a rule that specifies that the ventilation should be on, a signal value of 1 will have no effect on the other rules. It is only when all signals are 1 that the ventilation will be completely on at the maximum value as entered by the user.