Motorcycle cover

In my experience with a segmental concrete garage, almost any fabric prevents the metal from radiating heat up into nowhere.  If they radiate heat, they cool down to lower temperature than the air, and condensation begins.  Even the cheap weed resistant black woven fabric will do (cheap and keeps my car windscreen clear of frost also).

 It's a good idea to have something waterproof over the bike to protect from drips if you get any condensation under the roof.  I try never to leave them uncovered, and they don't seem to suffer.

If I flip back the cover on a cold night, a chromed tank begins to steam up almost immediately.

Ventilation is good also, so it doesn't get more humid inside than outside.