First: Is it possible to visualize airflow as a heatmap?

Yes! The Snowdon Towers Sample Facility includes a heatmap configured to visualize airflow as standard, and there are a number of library parameters available for air flow properties by default - and you can create any v

 

Second: Besides connecting Connections to Relationships one by one in the model, is it possible to assign Connections to Elements in bulk using Excel or the Tandem API? I would appreciate any good solutions you might have.



This forum post may help you with this for excel:

Streams Highlight – Assigning the Host of Streams in Bulk Just Got Easier! - Autodesk Community

 

Hope this is helpful for you!