Alex Steffen gave a smashing opening keynote to the inaugural SXSWeco conference in Austin today, sharing a host of predictions on how sustainability might best be incorporated into a future society. Clean energy? Nice, but it doesn't stand a chance at meeting current, much less future, demand. What really matters? Redesigning, and in some cases re-building the built environment in which we live.

Essentially this is about density. But lest folks fear they'll be co-opted into some god-awful Hong Kong high-rise, what matters more is increasing the *average* density in which we live, not suggesting that everyone lives the same way. In other words, Steffen advocates building a few high rises here and there, acting like tent poles, that raise the general average among more or less traditional suburban and urban areas - all connected by walking, bicycling, and sensible transit.

The key take-a-way? People care less today about building their "dream house" and rather more about finding the "dream neighbood." It's logical in places like Manhattan where people defend their tiny apartments by saying "well, that's just my bedroom, the city is my living room..." But even in areas with more generous real estate allotments, walkability and the richness of the local area are growing in importance.

The proof is out there. Take a look at Walkscore.com for example. It's a simple google map application that figures out just how "walkable" a given address is. It measures, among other things, how close you are to stores, restaurantes, and so on. A high score has been shown by the NYtimes to result in as much as a $30,000 premium onto the value of a home. Most Americans may not be ready to give up their cars, but an increasing number are clearly excited about the idea of being able to walk to the store.

From a sustainability perspective, the argument for walkability and density is obvious: Less energy spent on transportation, less time wasted in traffic, more local businesses patronized & more community spirit stoked. Amazingly, removing parking on some streets actually results in more commerce being transacted, not less. Throw in some bike lanes and you'll really be in business.

To a certain extend this trend may be a matter of economics - it's just not that affordable any more to build a fortress in exurbia. It's also a bit generational - kids growing up in far flung suburbia rediscovering the city. But it's also about folks starting to understand that most basic tenet of sustainability - systems thinking. A healthy pendulum swing back to the center after a few generations of suburban sprawl, systems thinking implies the recognition that one is a part of something bigger, and that building a home that is a functional part of a community is actually a good thing.

The energy savings and other sustainability benefits are icing on the cake.