Why it seems like just yesterday I was harping on the notion that, as long as our public policies yield built environments in which eco-friendly choices are difficult, eco-friendly choices will not be the norm.

Today I find a superb illustration of my pet notion in the Wall Street Journal, in the form of an excellent piece by Jeffrey Ball. I beg of you: go read it. (Of course, you can’t unless you subscribe to WSJ, which you don’t, so …)

It’s about people trying their best to conserve energy (you might recall that the president wants us to be "better conservers") in Houston, Texas. Long story short: it ain’t easy.

Admittedly, one part of the problem is the typical American craving for luxury and comfort:

Karl Rabago, an efficiency expert at the Houston Advanced Research Center, a nonprofit think tank, also knows the contradictions of energy-efficient living.

He chose a house just 6½ miles from his office in The Woodlands, an environmentally oriented community north of Houston. That lets him commute by bicycle, usually wearing a green T-shirt emblazoned with the message “ONE LESS CAR.”

He and his wife picked out a house in which the rooms they use most face north. That way, they get less direct sunlight, cutting down markedly on air-conditioning use. “Ninety-five percent of my energy conservation comes from the decisions I made in advance,” Mr. Rabago says.

The house has a swimming pool out back, a fitness room upstairs and 3,600 square feet of interior space. He and his wife paid about $340,000 for the place, in which they live alone.

“Yeah, it’s way too big for two people,” Mr. Rabago volunteers sheepishly, as Simon & Garfunkel’s “The Sound of Silence” plays from speakers connected to his iPod. The Rabagos bought a large house because they figured it will earn them a higher profit when the time comes to sell. “I’m not into sack cloth and ashes,” he says.

But then there are zoning laws:

Yet when he requested a metal roof, which would have reflected even more sunlight, his builder said the subdivision allowed only shingles made of asphalt — a petroleum product. When Mr. Gresham proposed covering his front yard with rocks and native plants that don’t need watering, his subdivision’s homeowners association told him he had to stick with grass. “It protects their property values,” explains Diana Barak, director of operations for PCMI, a Houston firm that helps administer the homeowners association.

And of course don’t forget outmoded cultural connotations:

The spiral-shaped [compact florescent] bulbs use about one-quarter the energy of conventional lights, generate less heat, and usually last several years. Still, the bulbs remain an oddity. Two years ago, when Mr. Rabago and his wife put their old house near Minneapolis on the market, their real-estate agent advised him to remove the fluorescent bulbs and to put back the conventional models. “Sorry, Karl, don’t try to sell your lifestyle,” he recalls the agent saying.

So anyway, perhaps Houston is an extreme example, but the point remains: Most places are built such that eco-unfriendly habits are deeply ingrained and difficult — economically, socially, and just practically — to break.

But note this:

There’s a paradox at work in the way the U.S. consumes energy. The American economy is getting more energy-efficient. Partly because of a shift toward lighter industry and service work, and partly because machinery is getting more efficient, the U.S. today uses only about half as much energy as it did in the early 1970s to produce every dollar of gross domestic product. Yet the average American’s personal energy consumption isn’t going down.

You could view this as a troubling paradox, or you could just view it as good news. Ultimately, the large-scale energy-use picture does not hinge crucially on the personal habits of the citizenry. Changes in technology and public policy ultimately have far greater repercussions.