TAD now has an excellent Workbook feature. (From Version 6.8.9.0 onward) You save values from the models you are working on, directly into the sheets inside the Workbook and perform calculations -- just the way you would do in a spreadsheet program. Though it does not have the bells and whistles of a fully-fledged spreadsheet program, you can save the workbook as an XLS or XLSX file. This feature is because of an innovative open source code which I managed to integrate into TAD.
There is only one Workbook in one session -- it can take in inputs from any of the open TAD models. That way, you can compare between various alternatives of the same project a lot meaningfully. You can now practically do any kind of calculations right inside TAD itself! Quantities, Advanced calculations for acoustics, lighting, etc.
As I have just incorporated a new feature; kindly let me know if there are bugs here.
I am running out of funds. It would be nice if you can make a donation... especially if you want to use such advanced features without a "nag" that TAD now has incorporated.