In the following interview, we speak with Jeff Speck, author of Walkable City: How Downtown Can Save America, One Step at a Time. Speck is an architect and city planner in Washington, D.C., oversaw the Mayors' Institute on City Design, and served on the Sustainability Task Force of the Department of Homeland Security.

The "sustainability" label gets applied to many things, from lifestyles to consumer goods. Does buying more green goods contribute to sustainability? Does living sustainably mean denying yourself and going without? Speck examines some of our conceptions and sets the record straight.

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Isaac Pino: That wraps up what I had. I'm sure there's a couple of questions out there. Anyone else who'd like to jump in? Matt Trogdon has the microphone.

Matt: Yeah, I have the mic. It has a cord, so you might have to walk up here. Miss Sarah.

Sarah: Thank you. Hi. Thanks for coming today. I'm just wondering what you think of Mayor Gray's recently released Sustainable D.C. Plan, especially as relates to your area of expertise.

Jeff Speck: I haven't read the plan. I know that it comes essentially out of the Planning Department, which is run by Harriet Tregoning, who is a genius and one of the best planning directors in the country. She's been doing these things for many years, in different forms. I'm confident it's very good, and I'm hesitant to say anything more about it, not having read it.

I would say that it's a little frustrating to see cities like Washington and New York City, and other cities that are so much greener than the typical American city, wearing the hair shirt about having to become more sustainable -- which I'm all for. There are many other cities in the country that need it more, that aren't doing as much to make themselves sustainable as D.C. or New York City, or San Francisco are.

But I do want to say that I think, and I'm not the only person who feels this way, that the whole sustainability argument is a little bit misconstrued, in terms of what people think makes them more sustainable.

The example I give is that changing all the lightbulbs in your house from regular lightbulbs to energy-savers will save you as much energy and carbon in a year as moving from the suburbs to the city will do in a week.

There's been all this focus on "What can I buy?" This is such an American approach. "What can I buy and add to what I already have, to make myself more sustainable?"

I did it when we built our house. We built a house in the District and we got the 12 solar panels on the roof, the solar water heater, the bamboo floors, the dual-flush toilets. A log burning in our super-super-high-efficiency wood stove supposedly gives off less carbon than if it were left alone to decompose in the forest.

So we have all this stuff that added considerably to the cost of our house. That's what we're taught sustainability is.

The whole LEED phenomenon, which I think is useful and important, can be a "get out of jail free" card that ignores more important issues like "Where am I located?" and "How am I getting to and from my house, my office?"

I was biking the other day and I was behind a bus, a tour bus, and it said "Eco Bus" on the back. I'm like, "Why is this an Eco Bus?" It probably has a somewhat more efficient engine than a typical bus, and buses are better than cars, but the point is that anything that's slightly better...

Someone else said this, but someone will advertise a hairbrush that's plastic as sustainable because they didn't cut down a tree to make it, and they'll advertise a wood hairbrush as sustainable because it's natural. We're able to attach this title to anything that we do, and it's always about buying stuff.

I think we should look more carefully at how we live our lives, as opposed to what we're purchasing.

That sounds like some sort of Calvinist admonition, and what I want to add -- this is kind of the summation of the discussion of the three reasons why we should be more walkable in the book -- is that it turns out that the cities that have the lighter carbon footprints are the cities with the higher quality of life.

There's a few different surveys -- the Mercer Survey, the Economist Survey -- of quality of life, that measures 12 different categories, from education to landscape to climate; all these different things. What constitutes a place that people want to live in?

The places where we drive less are the places that do the best on that. And health care, and everything else. There's this correlation.

It isn't that being sustainable makes you happier. It's that the same things that make you sustainable, if you do it right, the same things that make you healthier and wealthier, if you do it right, will also make you happier.

There's this illusion that we have to suffer to be more sustainable. That's the second illusion, after the illusion that we have to buy stuff to be more sustainable, but it's equally misconstrued because if you do it right, it's a complete benefit in every way.