There’s an unmistakable hokiness to Reynolds’ terminology; it veritably begs to be dismissed in favour of a Le Corbusier slab with triple-glazed windows. Then again, the industrial age took its lead from an effete and avowedly socialist Parisian intellectual in owl glasses and a bowtie who favoured bicycles and dinner in Left Bank bistros, so how strange would it be if the sustainable age started with a stubble-chinned, silver-maned survivalist with a Kentucky drawl and a hippie’s weakness for ethereal proper nouns? Capture him in the right light, and he could almost be a sort of parallel-dimension modernist — starting from an earthly zero composed of dirt and discarded rubber and the light and life-giving warmth of the sun — and his work is, at any rate, worthy of a declaration of its own. To wit: if there is to be a civilization a hundred years hence that is sufficiently functional to permit discussion of the history of architecture, then its dwellings will likely owe more to the design philosophy of the Michael Reynolds school than to anything that traces its origins to the deconstructivist show at the MoMA.

Right around the time Peter Eisenman’s art gallery was being feted, Reynolds began work on his first commissioned Earthship, on a gentle sage-covered slope on the outskirts of Taos. Fifteen years later, I checked into the place for a week’s stay with my wife, my daughter, and a friend from Manhattan, to attend Reynolds’ Earthship-building seminar.
It was a 65-square-metre cottage, which its original owner had dubbed the “Suncatcher,” and which she liked so much she had Reynolds build her another just up the hill. Though Reynolds would soon tell us that even five-year-old Earthships could do with a retrofit in accordance with the more polished design he’d developed, the Suncatcher was still just fine without a single major renovation.

It was, first of all, not a yurt. It had ample electric light, running water, a hot shower, a gas stove to cook dinner on, and a fridge for my daughter’s bottles. It had skylights with clever gravity-powered opening mechanisms, and they did not leak. The interior reminded me a bit of Mediterranean-style holiday villas I’d seen in the south of Portugal — smooth mortar walls, tile floors, rounded corners and doorways — though I’m sure it bore an even closer resemblance to New Mexico’s ubiquitous pueblo revival homes. We were urban people with a toddler in tow, and we had no complaints.

This is all worth noting for two reasons: first, because this easy functionality was the product of one of Reynolds’ first full-fledged experiments with a design entirely of his own invention; and second, because the Suncatcher, like all Earthships, was practically self-sufficient. Whatever forms sustainable shelter will one day take, it seems reasonable to begin from the avant-garde zero of complete gridlessness, and Reynolds has been there since the late 1980s. Aside from the gas hookup for the stove and the backup water heater, the Suncatcher was completely untethered.

Like most Earthships, it was built as a series of deep U’s, their open sides lined up against a south-facing wall of glass. The north-facing wall backed onto a berm of piled earth, giving the house a low-slung, half-submerged profile somewhere between The Hobbit’s Bag End burrow and the Tatooine farmstead of Luke Skywalker’s youth. The front corridor was lined by a narrow greenhouse fed by the home’s non-sewage waste water, which is partially cleaned by the plants therein en route to the toilet. (Theoretically, the greenhouse could be used as a subsistence garden — Reynolds likes to point out that it can grow bananas in the desert — but in the Suncatcher, as in many contemporary Earthships, the foliage is mostly decorative.) And there was a small six-panel photovoltaic array connected to a small battery bank in the foyer that supplied all of the house’s electricity.

All of this, though, is set dressing for Reynolds’ revolutionary breakthrough, the core principle he has established for the field of sustainable architecture, which is encased in the Earthship’s walls. The walls of an Earthship’s U-shaped rooms are constructed of recycled tires pounded full of earth and mortared in place. They provide the storage medium for its passive-solar heating and cooling system — its thermal mass, that is. Reynolds’ work amounts to a radical experiment in thermal mass, which he has discovered does most of the work of sustainability all by itself.

In a 1996 primer on the uses of thermal mass for designing “energy-conserving buildings,” Bruce Haglund and Kurt Rathmann of the University of Idaho outline a handful of critical elements that read like academic translations of the results of Reynolds’ single-minded, unconventional field research. “Ideal thermal mass,” they write, is found in materials with “a high heat capacity, a moderate conductance, a moderate density, and a high emissivity.” This rules out a number of the modern world’s most common building materials, including wood (which neither stores nor conducts heat well), steel (which reflects too much heat and conducts what it does absorb too quickly, resulting in a “storage cycle” of mere minutes), and glass (which is also too reflective and doesn’t trap certain kinds of heat energy at all). “Concrete and other masonry products,” they conclude, “are ideal.” The “cardinal rule,” Haglund and Rathmann assert, is that the thermal mass be placed “inside the insulated skin of the building.” The resulting system functions “both diurnally and annually,” by which they mean that the thermal mass stores the day’s heat to warm the house at night, and it also traps the heat of summer to warm up the winter.

Most of what an Earthship is and why it looks like it does has emerged from Reynolds’ efforts to maximize its passive-solar aspect. The earth berm hugging the north wall of tires, separated by a layer of whatever insulation is cheapest and most readily available, provides the “insulated skin.” The sloping, south-facing windows are designed to maximize heat gain in winter and minimize it in summer. And the walls of tires? Those started, Reynolds concedes, as “a contrived effort to recycle.” This was back in the 1970s, when he was not long out of the University of Cincinnati’s architecture school and toying with domes and pyramids built from scavenged junk on a mesa outside Taos. It turned out, though, that thick rubber stuffed with compacted dirt was at least as good as concrete brick for adding thermal mass, and much cheaper. “I’ve said it a thousand times,” Reynolds says. “If I was paid, in a grant, $30 million to invent two of the best building materials I could invent, I would invent tires and cans.”

As the years went by, he refined his design, reducing the daily and seasonal temperature fluctuations inside his structures, one degree at a time. He also discovered that adjusting the depth of the U’s and the slope of the windows made the design adaptable to almost any climate on earth. In addition to the the walrus 92 high-altitude desert of the Taos Valley, home to three full-fledged Earthship communities, Earthships have been built in the Bolivian jungle and the snowy mountains of British Columbia, in rainy Scotland and sunny southern California. Reynolds has run into inflexible building codes and intransigent inspectors at all turns, but still the thermally massive buildings have done their job. “I’ve spent 75 percent of all my time, all my energy, and all my money getting permission to do this stuff,” he has said. “Only 25 percent has gone into actually doing it.”

Reynolds likes to describe himself as a miner of knowledge, and he’s definitely something of an accidental archaeologist, because thermal mass is a building concept nearly as old as human civilization. Indeed, one of the most dramatic pre-industrial exercises in thermal mass occurred not far from Taos, at the Ancestral Pueblo village of Mesa Verde in southwestern Colorado, an elaborate thousand-year-old settlement built into an alcove in the middle of a cliff face, which some experts claim took advantage of the great stone wall’s passive heating and cooling, as well as the shade of the rock overhang. More recently, several of Frank Lloyd Wright’s houses featured thermally massive floors, and the aforementioned Santa Monica modernist cube featured in Dwell relies on a thermally massive concrete slab floor for much of its vaunted energy efficiency.