https://community.graphisoft.com/t5/Collaboration-with-other/Expression-question/m-p/273153#M35809 Hi Mats,<BR /> <BR /> Can you copy your code or the part of the code that is not working?<BR /> The one below seems to work fine for me (Data Type: Number).<BR /> <PRE>{Property:Wall/Area of the Windows} / {Property:Wall/Gross Surface Area of the Wall on the Outside Face}</PRE> /Martin Tue, 19 Nov 2019 12:30:03 GMT Anonymous 2019-11-19T12:30:03Z https://community.graphisoft.com/t5/Collaboration-with-other/Expression-question/m-p/273152#M35808 <DIV class="actalk-migrated-content"><T>Hi,'How can I calculate total area of windows in the exterior walls divided by total net area of outside of exterior walls? I get a result only by using the one windows and wall area but it's the inside of the wall which is not what I want. When dividing window ara by wall aoutside face area I get no result (property as number and available for all...)<BR /> Br,<BR /> Mats</T></DIV> Mon, 18 Nov 2019 20:39:31 GMT https://community.graphisoft.com/t5/Collaboration-with-other/Expression-question/m-p/273152#M35808 Mats_Knutsson 2019-11-18T20:39:31Z https://community.graphisoft.com/t5/Collaboration-with-other/Expression-question/m-p/273153#M35809 Hi Mats,<BR /> <BR /> Can you copy your code or the part of the code that is not working?<BR /> The one below seems to work fine for me (Data Type: Number).<BR /> <PRE>{Property:Wall/Area of the Windows} / {Property:Wall/Gross Surface Area of the Wall on the Outside Face}</PRE> /Martin Tue, 19 Nov 2019 12:30:03 GMT https://community.graphisoft.com/t5/Collaboration-with-other/Expression-question/m-p/273153#M35809 Anonymous 2019-11-19T12:30:03Z