Men living outside hometown, how'd u all stay inside your flat/PG room, Shirtless or with something? Need advice.

Recently, for the first time I've shifted to a flat with random flatmates... AT HOME I used to wear just a shorts and be half naked all time . But here my roommate says it feels weird and asking me to put on something, I've asked his sexual orientation (to know whthr he's bi) and he said straight. So I got curious of what's making him uncomfortable.

also my job requires a coat all day long, so I just want to feel free and cool at home.

Please suggest me what I should do.