The properties VacancyRateInCategoryNow and VacancyRateInCategoryFuture are defined by the data type IfcPositiveRatioMeasure. The values are given in percentage 0% <= value <= 100%. It is importante also to set a value to 0%. This is with the data type IfcPositiveRatioMeasure not allowed.
Solution:
New data type IfcNonNegativeRatioMeasure
Another solution would be to use IfcRatioMeasure, but to allow negative percentage values are in this case not the best solution.
The properties VacancyRateInCategoryNow and VacancyRateInCategoryFuture are defined by the data type IfcPositiveRatioMeasure. The values are given in percentage 0% <= value <= 100%. It is importante also to set a value to 0%. This is with the data type IfcPositiveRatioMeasure not allowed.
Solution: New data type IfcNonNegativeRatioMeasure
Another solution would be to use IfcRatioMeasure, but to allow negative percentage values are in this case not the best solution.