That Wikipedia article explicitly says that making this concept work in a tropical climate (we're talking Florida, right?) is so far an unsolved problem, and th

That Wikipedia article explicitly says that making this concept work in a tropical climate (we're talking Florida, right?) is so far an unsolved problem, and that the one example in Louisiana does in fact have an AC. Not needing AC by having decent insulation in Germany or Scandinavia (which is where most passive houses are located) is a _much_ easier problem than not needing AC in Florida. Of course not needing _heating_ is a big problem there, and is what the passive house designs are mostly aiming to deal with.