“Expression cannot be evaluated for this Element”.

[Anonymous]

We recently jumped from Ver 20 to Ver 23 (International)
So testing Classifications and Properties feature.
Kindly see attached image.
All Morph elements have separate Classification.
However the evaluation of “Balance Area of Plot” fails stating “Expression cannot be evaluated for this Element”.
I did not find any post on this error, so bothering you. Please reply early.

[poco2013]

Available classifications for properties are set in the Property Manager not in the Classification Manager.

In the Property Manager, for each property and expression used, Under the 'Availability for classifications' tab include all of the classifications for all three morphs for all properties. This will make the expressions you created visible to each of the morphs. However, Archicad presently has no ability in schedules to subtract areas from different elements and then create a total. You may want to use zones and calculated areas.

[Anonymous]

“However, Archicad presently has no ability in schedules to subtract areas from different elements and then create a total. You may want to use zones and calculated areas.”
Many thanks for admittance!

This is important to note. We in the office, after having trying all possibilities suggested by moderators had already come to conclusion that Expression defined properties do not work on different elements simultaneously. Besides Classification is a poor method to classify elements when there are 100s of parameters to include to classify elements.

Archicad 6 introduced “Calculations of elements, components and zones” way back in 1997. It is disgusting to note that there is no improvement at all in the algorithm/ process in it since 1997. Even Archicad 23 carries the same method without any improvisation after 17 versions later. Eric Wilk wrote the famous book “Archicad: From CAD to Quantity Survey”. We tried to use methods shown by him. However even Eric states in the book that reports through Graphic Templates are difficult to formulate. There is no simple and proper language along with proper documentation to create template suitable for your office standards. Even Archicad reference manuals state not to fiddle with the Template code. Besides by now all Archicad users have agreed and resigned from creating reports from those templates. It is also to mention that reports from those templated cannot be exported for any further use, which is a necessity in AEC Costing and Estimation.

Text lists in the calculation menus are just lists given away by the software and they cannot be added with custom parameters which is possible to some extent with Graphic templates.

No one can deny however fantastic a design may be, it cannot be constructed without a detailed estimation and component quantities which unless documented in industry standard format are useless for a contractor or a site personnel to understand. Architects and designers for many centuries have created impossible-to-imagine-before-designs with simple tools.

Now after 17 versions later (23-6) Archicad has not arrived with a proper Estimating and Costing Interface which generates reports in Industry standard format of
SpecificationCode|Description|L|B|D|Quantity|Unit|Rate|Unit|Amount.

Many practitioners here, quote that they export data to spreadsheets to process it further. However I fail to understand reliability and safety of spreadsheets to handle data worth millions. Besides export means disconnection of the data from Archicad. Design is a continuous process. How many times will one export data and keep its integrity with the BIM model? And what about synchronisation of the new data with the old one? Does anyone agree that all this can be done with much boasted “Expression defined Properties?

I have never seen a presentation by any practice about Estimation and Cost Management through Archicad’s Building Information Model in much boasted KCC’s during launces of newer versions. I wonder how those large practices manage Estimating Costing and Constructions of their large projects. At least I have not so far come across any work-flow of the Lifecycle of a project of which “Estimation-Costing-Bidding-Measuring-Variance” are spine either in KCC or on Web. I come from a country where most form the AEC industry still use AutoCAD. I am the one around me who has been using Archicad for last 25 years. Since there are no peers to consult with I am solely dependent on the web and manuals so if anyone feels that I do not have knowledge of how Archicad BIM is used for entire lifecycle of the project I apologize beforehand, but at the same time expect them to share the process for my knowledge.

Till then I am of the view that Archicad is a sophisticated 3D modeller and wonder if it is a BIM software.