Occupancy Design Validation with Expressions

by George Primikiris · updated: 06.22.2018

A new feature of ARCHICAD 22 helps to turn the raw data into meaningful and valuable information. The expression-based properties process model data with functions and operators to produce new information which was not available directly in ARCHICAD.

Graphic Overrides linked with Expressions enable ARCHICAD users to test their designs with instant graphical feedback in various design validation scenarios including certain level rule-based checking in the concept design phase.

The syntax of an expression is very similar to the so-called formulas used in spreadsheet applications. An expression can be consisted of functions, operators, parameters and properties, numeric values, unit declarations, strings (texts) and grouping, delimiter or separator characters.

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Calculate and Define Occupancy with Expressions

In the example below we will test if the designed room area meets the occupancy criteria defined by the room function. This value varies between certain limits depending on the activities taking place in the room. The maximum capacity of a room (e.g. the maximum number of accommodatable occupants) can be calculated by dividing the floor plan area of the room by the minimum acceptable floor plan area per occupant value. Finally, the design can be validated by comparing the planned number of occupants against the maximum capacity of the room.

Based on the design requirements we set desired number of occupants for each zone at Classification and Properties. These values are shown on the zone stamps as well.

At first we need to create the following expression-based properties:

  • The property named Area per Person sets the minimum required plan area for a single occupant. The particular numbers can be taken from the occupancy standards of the building codes. We can set different values for each space category (which are implemented as Classification entities in ARCHICAD) with the help of the IF logival function. (The expression below is tabulated for better understanding, the Expressin Editor allows single line input only!):

  • The property called Calculated Max. Capacity calculates the maximum capacity of each ARCHICAD zone based on the Calculated Area zone listing parameter and on the previously created Area per Person property. The result is rounded down to the nearest integer with the ROUNDDOWN function to prevent exceeding the limit set in the building codes.

  • The Occupancy Standard Compliance compares the planned occupancy load with the maximum capacity allowed by the regulations and provides a clear feedback in form of a Boolean values: the value is set to TRUE only if the zone is compliant with the standards (eg. the calculated capacity of the zone is equal or bigger than the planned number of occupants).

Using the above created expression-based properties we can make a schedule to have an overview of all the factors taken into account in this design validation scenario:

  • The space classification type of the zones is in the third column.
  • The Area per Person value comes from the regulation and depends on the space classification type.
  • The Calculated Area is a zone listing parameter of ARCHICAD.
  • Occupants in the sixth column is a planned value based on the client’s need.
  • The Calculated Max. Capacity calculates the maximum number of accommodatable occupants for each zone depending on the Calculated Area and the Area per Person.
  • The Occupancy Standard Compliance in the last column compares the planned number of Occupants against the Calculated Max. Capacity and returns True only if the former is smaller than or equal with the latter, otherwise the returned value is False.

Display results on Zone Stamps

The calculated results can be indicated on Zone Stamps as well:

  • Select all zones and open the Zone Selection Settings dialog.
  • Navigate to SETTINGS > Classification and Properties.
  • Select the 2. Row and select CALCULATIONS > Calculated Max. Capacity from the list.
  • Select the 3. Row and select FORMATTED RESULTS > Occupancy Standard Compliance from the list.

Apply Graphic Override to visualize the result

Graphical Overrides provide instant visual feedback revealing design problems and compliance issues. It is very easy to define a criterion for Graphic Override Rules in ARCHICAD based values of expression-based properties.

The criteria in this example is based on the Occupancy Standard Compliance Boolean property. Separate rules have been defined for zones which proved to be compliant (green) and for zones which failed on the compliance test (red) at Document > Graphic Overrides > Graphic Override Rules.


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