I am not quite sure what you are trying to achieve, but properties (with or without expressions) are only applicable to one element.
They can not get information from other elements.
So you could create a property to determine if a door is right handed and you would get a value of 1.
Then you could schedule that property to sum the number of right hand doors.
But it is just as easy (if not easier) to simply schedule all right hand doors as rsuleyman1 showed.
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