Why is Hank always in sweaters?

The weather looks a lot like it's summer, yet both times they show Hank in civilian clothes it's always a sweater and not even the same sweater. This isn't a major issue, but you don't see anyone else walking around in a sweater and it just seems really odd. Does he not own a short-sleeved shirt or even a long-sleeved shirt? Tony and Jan wear the same civilian outfits and they don't stick out especially for what looks like summer. It seems really weird especailly when he also wears a lab coat all the time. He's not even outside so it's not the sun.