I was in another, unnamed state recently – very, very far west of our home in Boulder, Colorado – and the experience, at least from a green point of view, was almost antediluvian, like I had disembarked the plane in 1950. Recycling was a completely foreign concept; the obvious fate for garbage was to burn it. Styrofoam packaging seemed like a really neat idea. There were some legit crusaders out there (ironically, I whiled my time driving a fully biodiesel rental), but the whole thing, frankly, was a sharp reminder of how most of the world thinks of the environment: They don't.

One of the aspects of living in Boulder – and I'm not sure yet whether this is positive or negative – is that 75 percent of the population at least thinks green.

Not very long ago, I'd been pretty down on Boulder. It's a little secluded, both geographically and socio-intellectually, for my tastes. Sometimes it has the feel of a gated community: People want things the way they want them; variance is intolerable. And you get the cognitive dissonance that stems from seeing a Chevy Dinosaur parked in the Whole Foods parking lot with the engine running and the AC on – and the John Kerry bumper sticker on the tail – while its owner goes in to shop.

But it hit me, out there in the sticks, that Boulder is an amazing place, really one of the genuine headquarters of the green movement. We've got everyone from leading lights like David Johnston to guys like Blake Jones, who are maybe small-timers at the moment but are working toward important futures. We've got Amory B. Lovins just up the way. The local university has won the solar decathlon every time it's been run (go Buffs!). We've got EcoCycle, the Resource yard, the Center for Resource Conservation; a city council that's pushing to meet Kyoto standards and is a smart steward of open space; and the state constitution now includes Amendment 37, the first voter-initiated renewable energy standard in the country.

We've also got the annual Solar Home Tour, a self-guided visit to 30-odd green houses around town: all operating on some degree of solar power, but also xeriscaped or hyperefficient or geothermally heated. And not just brand new, built-from-the-ground-up seven-figure "residences," but 1,200-square-foot ranch-style homes built during the Cold War but now full of clever retrofits.

The big highlight of the recent 2006 tour was the Solar Harvest House, just built in 2005: a five-bedroom, 4.500-square-foot home that runs almost entirely on solar power, without help from the local utility. There is no backup boiler, no water heater, no furnace; the house's walls and windows are tight enough to keep the indoor temperature at 68 degrees when it's 2 degrees outside for 8 sunless days. (The only natural gas they use is for cooking.) Thermal and PV solar panels line the roof, with a 6,000-gallon hot water storage tank built into the ground and superinsulated to R-98 (!) for their domestic hot water and radiant heating system. A geothermal exchange system helps with heating and cooling: outside air is drawn into a 270-foot-long underground tube (buried 8 feet deep) and then circulated into the house. In summer, when the earth is relatively cooler than the air, 105-degree outside air is drawn in, cooled by the earth to 68 degrees and sent (via solar-powered fan) into the house to keep it cool. In winter, 5-degree outside air is drawn first through the relatively warmer earth to preheat it to 38 degrees before it moves into the home's heating system. The owners pay $12 a month for a utility meter – but they end up in the black every year because the power company pays them for the excess electricity the house generates. Usage for the past 12 months is at something like minus-1000 kilowatt hours.

Eric Doub, the builder and owner, claims the house cost him 8% more per square foot to build than a typical custom house in Boulder. On a $1.2 million house, say, that would be an extra hundred grand. During the tour, someone asked him what he expected the return on investment to be, how long it would take him to make back that 8% via saved energy costs. This is what he said: "I don't even know, and I don't really care. No one ever asks what the payback of a granite countertop is, when everyone knows it's going to be the avocado green cabinet of the near future: People will just want to get rid of it, and it'll go in a landfill. We've got the comfort of knowing we've got a house that's going to be viable and tight in 20 years, 50 years, and we'll never need the utility company."

Sure, I guess you can be that cocky when you can afford to build a seven-figure home. But his company, EcoFutures Building ("Construction with a Conscience"), also built a Habitat for Humanity house down in Denver – something like 1,200 or 1,300 square feet – for (I think Doub said) under $400k. No boiler, no furnace; all solar and geothermal. Like building a future directly into the home: Whoever moves in won't ever pay a cent in utility bills, giving them that much more of an economic foothold.

Really inspiring and amazing stuff. And if there's a non-green message to glean from all this, it's that you could make some serious money by being a green contractor. The level of what's possible, just in terms of energy efficiency, far outstrips the level of general understanding. We recently had a plumber tell us that an 85-percent efficient boiler was the most efficient one on the market. He wasn't even close. We found a 97-percent efficient one (which I'll be telling you about soon), but there are 94 percenters, 92, 87. And he just didn't know about them. And I think that's the case everywhere. Contractors and builders have less and less idea what people want to spend money on, so they're still caught up in granite countertops and elegant sconces when what people are starting to really want is better insulation, more efficient homes, lower heating bills. The statistic Doub kept repeating was that a 3%-5% increase in initial costs, spent on efficiency measures, would cut 30%-50% off the lifetime system cost – heating, cooling, electricity, gas.

Solar Harvest is the most energy efficient home in Colorado. I doubt our place is going to beat that, but aiming at least as high is a pretty good goal.

NEXT WEEK: Our age-old boiler broke down. Finding an efficient one to replace it isn't easy, even in Boulder.