[dba-SQLServer]Union query disk space

I need to combine data sources that feed a BI program (Cognos). The
equivalent process with pure SQL Server would be to have a view that
SELECTs from another view containing multiple UNIONs. My question is:
Will this result in a table in TempDb representing the UNION'd tables? 

If so, I don't have enough disk space. I'd rather not try it out blind,
do I'm grateful for any ideas.