[William Tell]

ProtectOurFreedom said: "... but the air in the bubble would go really stale really quickly ..."

Not necessary at all.

Assuming that the "bubble" is sufficiently leak proof, it would only be necessary to provide a controlled opening matched to the pump providing conditioned air to get all the air changes one would want.

The biggest problem I see would be preventing condensation on the inside of the bubble due to the cold outside. There would also be considerable heat loss through the material of the bubble. Air changes? Not a worry.

[Bellflower]

The biggest problem I see would be preventing condensation on the inside of the bubble due to the cold outside.

I am really curious about how they deal with condensation.