As a Head of Department, how can I make my faculty happier? I am HoD for a department with over 30 members. 


The dept is socially inactive with only one or two social gatherings per academic year. 
No politics or "serious personal issues" among members. 
Just teaching while doing some research. 


I got a green light from (very) top management to make them happier. But I really don't know how!
It might be uncommon, but just ask them. 

You could use a basic questionaire if you want to do it anonymously, or you could talk to everyone in person. 

Just showing some activity does not help as long as you are having no idea about the needs and desires of your faculty members.