WIBTA - Housemate’s boyfriend has the a/c on ‘every time’ he comes over

I (19F)stay with my lovely housemate(20) I know it’s summer but ‘every-time’ he’s(20) comes over he has the a/c turned on. Yesterday was a top of 32C but when he came over around 10pm (18C) it was on. Everything is great with my housemate and I don’t want to start anything but would it be crazy to ask her to tell him to chip in on the elec bill? When it’s just us we never turn it on