Hi,
Looking at your screenshot, I think it works fine. Please take a look at the descriptions of "Conditional Surface area on Outside face" and "Net Surface Area on the outside face"
on this site.
Net surface area is reduced by every opening, so it reports the actual area in all cases. The reason the Conditional Surface area is different in some cases, is that it uses the rules from 'Options>Project Preferences...>Calculation Units and Rules...>Setup Rules'. This by default says that every opening that has a surface area that is smaller than 2.00 m2 should not be subtracted, anything that is bigger should be subtracted (see picture attached).
This means that when you only have Windows (1.5x1.5=2.25) or default Doors (0.9x2.1=1.9) in your wall, each of them are smaller than 2.0 m2, so they won't be subtracted, but if you place a door with a sidelight (1.5x2.4=3.6), that will be bigger, so it is subtracted from both the conditional, and the net areas, leaving them with the same surface area.
I hope this helps with your issue. Please take a look at the page linked above to find the name of the value you actually wanted to display.
Regards,
Daniel Alexander Kovacs
Professional Services Consultant
GRAPHISOFT
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