Yan420answered grow question 1y ago Hey growmie, the thing with folding the hose works in principle, but in winter, you can really get cold air coming back if you just run it through the wall like that. Especially when the fan is off.
If you drill through like with a range hood, it's best to install a backdraft damper. It doesn't cost much, but it prevents cold air from coming in.
Alternatively, a ventilation valve with a flap works too, or you can insulate the hose a bit, then the heat stays in better.
Overall, good idea, but make sure to secure against drafts, otherwise, it’ll stress you out in winter.