Calculate total glass area above a certain height.

[Bjoernar]

I am making a window schedule that sorts windows by the zone they are placed in and that calculates total glass area for the windows above 800 mm over the floor.

The total glass area in each zone i have solved, but i struggle to subtract the glass area that is below 800 mm from the floor.

Thanks.

Operating system used: Windows 11

[Botonis]

If you mean left or right, create a property that you can set the position of the mullion and then another one with IF or IFs for checking. But if you just have the first one maybe it is enough. 

[Bjoernar]

I struggle to make a poperty that can find the position for the mullion. Do you have a suggestion that can send me in the right direction?