After feasting on audio podcasts for years, I realized that I don’t always want somebody else’s voice in my head while running, biking, and hiking. So I went on an audio fast for a couple of months. But now I’m ready for more input, and I’m once again reminded how wonderful it is to be able to bring engaging minds with me on my outdoor excursions.

One of my companions on yesterday’s hike was John Ochsendorf, a historian and structural engineer who explores the relevance of ancient and sometimes forgotten construction methods, like Incan suspension bridges woven from grass. One of his passions is Guastavino tile vaulting, a system that was patented in 1885. Although widely used in many notable structures — including Grand Central Station — Ochsendorf says that some of these structures have been torn down and rebuilt conventionally because modern engineers no longer understand how the Guastavino system works, and cannot evaluate its integrity.

This theme of forgotten knowledge echoes something I heard in Amory Lovins’ epic MAP/Ming lecture series. He describes a large government building in Washington, DC, that was made of stone and cooled by a carefully-designed pattern of air flow. The cooling system wasn’t completely passive, though. You had to open and close windows in a particular sequence throughout the day. Now that building is cooled by hundreds of window-mounted air conditioners. I’m sure our modernn expectation of extreme cooling is part of the reason why. But Lovins also says that air conditioning became necessary because people forgot how to operate the building.

I love the idea of recovering — and scientifically validating — forgotten knowledge. That’s what John Ochsendorf’s research group does. One of his students, Joe Dahmen, did a project called Rammed Earth — a long-term experiment to see if that ancient construction method could actually work in present-day New England. John Ochsendorf says:

Historical methods of construction that are very green, very local, may create beautiful low-energy architecture, we’ve forgotten how to do them. So we have to rediscover them, and do testing to prove to clients and building owners that you can use these methods. And it’s a good example of MIT’s motto of mind and hand. We don’t like to just read about rammed earth walls, we like to get dirty and build them.

Very cool. I think the MacArthur Foundation invested wisely in this guy.