My solution was to use a variable (called occLoad in the example) to hold the occupant load property value and two If statements. The first tests for a zero value and sets a variable (called doCalc in the example) to indicate whether or not a calculation should be done. If it finds a zero value, the doCalc variable is set to 0 (do not calculate) AND the occLoad value is changed from 0 to 1. If occLoad is not zero, the first If statement only sets doCalc to 1 (do calculate).
The second If statement then tests the value of doCalc: if it is 1, it returns the result of dividing the area by the occupant load; if it is 0, it returns 0. Because the first If statement assures that the occLoad value will not be zero, the division in the second If statement never results in an error condition, and the desired result for an occupant load of zero is returned.
occLoad = [SpaceStylesCalcs:Occupant_Load] If occLoad = 0 Then doCalc = 0 occLoad = 1 Else doCalc = 1 End If If doCalc = 1 Then RESULT = [SpaceStyles:BaseArea] / occLoad Else RESULT = 0 End If
The example file also shows how a Property Data Format can be used to round any result with a fractional amount up to the next highest integer, since you would want that when calculating occupant loads for egress analysis. It also demonstrates using a style-based Property Set to hold the occupant load property, so that the occupant load value only needs to be added to the Space Style, and not to each individual Space.