Optimisation - Constraints

Accessed from Parametric, Optimisation and UA/SA Analysis Settings dialog

Optimisation Constraints allow you to impose upper or lower limits on a building Key Performance Indicator (KPI) such as Cost or Discomfort. Examples of constraints that might be applied to an optimisation analysis are "Discomfort hours must be less than 200" or "Construction cost must be less than $6m".

Note: The constraint KPI can be the same as a KPI used for an Optimisation Objective.

When viewing optimisation results with constraints applied you will find that some of the results generated don't respect the constraints. This is normal, however you should also see that many more new points are generated that do meet constraints because the optimiser favours such design variants when creating new generations.

Name

Your name for the constraint (e.g. "ASHRAE 55 discomfort hours < 200")

Constraint KPI

Select a predefined or custom constraint Summary Output Key Performance Indicator (KPI) from the browse list.

Less than or Greater than

Select whether the criterion refers to an upper or lower limit.

• 1-Less than - the KPI must have a value less than that entered in the next text box.
• 2-Greater than - the KPI must have a value greater than that entered in the next text box.

Value

Enter the upper or lower limit value for the KPI.

Units

The units of predefined KPIs are defined internally by the selected KPI itself. For custom KPIs the units are defined by the script that you write and in those cases it is usual to include the units within the name of the KPI. For example in the Custom Script KPI Tutorial the custom KPI created is given the name "EUI (kWh/m2)".