

While insulation helps, it’s fundamentally less efficient because the heat sync is inside the building and insulation isn’t foolproof. And often these units are made of plastic, so they leak more heat into the house from the chassis than you’d expect. Even the best hose is less efficient than a window unit where the entire heat sync is outside the building
So while $20 and some duct tape helps a great deal, it definitely won’t be as efficient as a window unit
As a (begrudging) customer this sounds good on paper. But I’m suspicious as hell