As you can see in the table below, half the staff always give their lectures in Catalan, whereas a third give them only in Spanish and 15.2% do so in both languages.
Language
Percentage
Always Catalan
54,8
Always Spanish
29,4
Mostly Catalan
5,2
Mostly Spanish
5,2
Both equally
4,8
English
0,2
No response
0,4
(Source: Com parlem a la UPC, a sociolinguistic survey of UPC conducted in 1991-92)