It doesn't have to be. They have a video where he hits the exterior with a propane torch - not all construction materials are the same. These appear to be qui

It doesn't have to be. They have a video where he hits the exterior with a propane torch - not all construction materials are the same. These appear to be quite well constructed and as long as they have figured out how to prevent air infiltration at the joints once it's unfolded and fully assembled these should be far more energy efficient than the vast majority of tract housing being mass thrown up.