RENEE MONTAGNE, HOST:
The planet may not feel any different today, but there are now seven billion people on it. That's what the United Nations announced yesterday. And as that number continues to rise, global incomes are likely to rise as well. That means more cars and computers, bigger homes, the kinds of things Americans take for granted.
As NPR's Christopher Joyce reports, it's that rise in consumption that's got population experts worried.
CHRISTOPHER JOYCE, BYLINE: There's still room left on planet Earth for more people. But is there enough stuff for them - land, food, cars, cell phones?
Klaus Lackner is a physicist at Columbia University's Earth Institute. He says as economies improve in places like India and Africa, where populations are growing fastest, they're going to want to live more as we do.
KLAUS LACKNER: It's very hard to c convince people to stop consumption.
JOYCE: But maybe the world's next billion will be happy with Hondas instead of Hummers.
LACKNER: I would expect consumption in the future gets larger, but we also learn how to do things more efficiently. And so the raw material consumption may well go down.
JOYCE: But Lackner says consumption will eventually go up again. You can only tighten your belt so much. And physicist Dan Kammen says there just isn't much incentive for rich countries to do that anyway.
DAN KAMMEN: In many parts of the world, energy is - and I hate to say this - it's simply too cheap.
JOYCE: Kammen is head of an energy laboratory at the University of California at Berkeley. He says cheap energy enables Western countries to live high on the hog and lots of other people want to copy us.
KAMMEN: There's a huge impact of the decisions that we make, and also we export a lot of technologies.
JOYCE: The problem is, there just isn't enough cheap energy or water or land for nine or 10 billion people to live the same way. So what if Americans set a different example, consume less by living smaller? The Japanese do it.
Can small be beautiful in the U.S.? Some people think so.
(SOUNDBITE OF MACHINERY)
JOYCE: In an industrial park outside of Sacramento, there is a factory inside what looks like an old airplane hangar. Zeta Communities builds modular homes here. Project manager Scott Wade says they're not like stick-built homes.
SCOTT WADE: Stick-built meaning they build it one piece at a time, whereas we build it an assembly at a time.
JOYCE: One assembly is the floor with duct work in it. The next. the walls then the ceiling, and so on. Workers make and assemble the parts for one home, about 1,500 square feet in a single day.
WADE: It is a higher quality because we have more control over it. We don't have the weather delays. We don't have that kind(ph) of stuff getting in the way.
JOYCE: Everything from the caulk along the walls to the lumber is certified green or from sustainable sources. The walls contain extra insulation and every hole is sealed to make the buildings energy efficient. Zeta claims that in the right climate, rooftop solar panels could provide all the home's power, a so-called net zero energy home.
Zeta founder and president Naomi Porat sees cities as her company's big market.
NAOMI PORAT: The population all around the world is moving toward the cities. Land is a vital resource and there's not a lot remaining, so we need to start thinking about very creative ways to use our space.
JOYCE: In cities, modules can be stacked to make a new generation of efficient buildings. At Zeta headquarters, architect Taeka Takagi rolls out blueprints with one of Zeta's prototypes.
TAEKA TAKAGI: It is a micro studio. The units are under 300 square feet.
JOYCE: That's truly micro, smaller than most suburban living rooms. Porat says there is a group who might find this alluring, though.
PORAT: They're hitting a - sort of what I call the technocrati generation and demographic that uses the city as its living room and kitchen, and goes to practically a dorm room to crash at the end of the day.
JOYCE: How do you convince someone to live this small?
TAKAGI: The psychology of convincing someone is to provide very simple things, like enough storage.
TAKAGI: I like to provide a large sink, so that the person who's using it doesn't feel like they're lacking or living smaller and everything is miniaturized.
JOYCE: Since buildings consume about 40 percent of the nation's energy, they're a logical target for more efficiency. But Berkeley's Dan Kammen says living smaller is not the ultimate solution. With nine or 10 billion people, rising consumption will overwhelm any efficiencies, as well as our current sources of energy. What's needed, he says, is renewable energy that's cheap and won't run out.
KAMMEN: And by essentially every measure we're not moving fast enough.
JOYCE: Christopher Joyce, NPR News.
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