I have a rich friend.  Just one really.  Whenever I ride in his car, I love the sound the doors make when they close. Unlike the tinny “clank” when the doors of my elegantly rusty SUV slam, his doors have a deep, reassuring, “clomp” sound.  Inside, you are cocooned, secure, padded, and hermetically sealed. More and more often, our buildings are “sealed” like my friend’s car and that isn’t necessarily a good thing. Modern building techniques and materials have given us an almost airtight envi ...