Have you noticed much noise from your PowerWalls? I think you have 4, right? We have two and unless I put my ears within a couple of inches they are silent in our garage. Never heard any vibration in the wall, unlike our wall-mounted tankless water heater.There aren't any gases other than atmospheric air that we all breathe which are regularly vented from the Powerwalls. As @Electrph mentions, there is a liquid cooling system with fans that make a little noise. When we were first planning on Powerwall installation locations in our garage, they originally mentioned not wanting to install them on walls where there was habitable space on the other side due to the low hum of the cooling fans/pumps.