Board Thread:General Discussion/@comment-69.136.104.77-20170602103746/@comment-27794543-20170605033143

As DrL said, the mansion & lab aren't bunkers. This is proven multiple times, e.g. Murphy & Emori were gathering supplies from the mansion & lab to stay in the lighthouse bunker (if they could've used the mansion or lab, of course they would have chosen the larger/nicer building rather than the tiny bunker), Becca told Chris to go the bunker (implying that it's the only safe place on the island), only the lighthouse bunker had an oxygen generator, etc.