In the past year and a half, Edward Mazria's 2030 manifesto has taken on a momentum of its own. Until recently, the 67-year-old architect was a principal in the successful Santa Fe, N.M., practice of Mazria Riskin Odems and lecturing about global warming on the side. But in 2007, Mazria, AIA, decided to spin off from the firm. He brought along a few staff to help run Architecture 2030, the nonprofit he founded to spread the word about architects' role in averting climate change. Or rather, the decision was made for him, since the groundswell of interest in his environmental research had begun to eclipse the practice. “This is all time-consuming,” Mazria says, sounding a tad travel-weary this spring after returning from back-to-back speaking engagements in Sacramento, Calif., Orlando, Fla., Miami, and Lafayette, La.

It's been several years since Mazria, a veteran of the 1970s environmental movement, sliced up the latest scientific data and concluded that the building industry is responsible for about half of America's energy consumption and the greenhouse gas emissions that contribute to global warming. Since much of the burden falls squarely on architects—he estimates they design 77 percent of all nonresidential buildings, 70 percent of all multifamily, and 25 percent of all single-family homes—he's begun asking the profession to incrementally reduce fossil fuel use in projects: by 60 percent in 2010 and by an additional 10 percent every five years until reaching net-zero nirvana in 2030. At each stage, he allows, 20 percent of those emissions targets may be offset by purchasing renewable energy credits.

Mazria's clear, urgent message has been embraced by individuals, firms, and architecture schools all over the world. The challenge has been adopted by the major building sector organizations, the U.S. Conference of Mayors, and a number of cities and states. Illinois recently legislated that all state buildings meet the 2030 targets. California adopted the benchmarks for commercial buildings and is requiring that residential units produce as much energy as they use by 2020. In perhaps the biggest triumph of all, last January the U.S. government signed the 2030 Challenge's energy-reduction targets into law for all federal buildings.

It's hard to imagine that all new buildings could be carbon-neutral within a decade or two. But the science is clear, and the technology is closing in. In the nation's northern climes, “even on cloudy days there's enough sunlight falling on each square foot of roof to get 10 times as much energy as the buildings need to operate,” Mazria says. “It's a matter of conversion. Solar technologies keep increasing every year. We think the technology will increase faster than the reduction targets.” However, he's asking architects to first tackle the problem through pure design. Passive solar strategies alone, he maintains, can reduce emissions by 50 percent to 80 percent. The rest can be made up with solar and wind power—technologies that are dropping in price.

“The latest reports are saying the price of generating on-site electricity using thin photovoltaic cells is expected to drop dramatically in a few years,” Mazria says. “We think the cost of going carbon-neutral will keep pace with targets as we go out in time. That's also why the targets are staged—to allow time for the cost to drop.”

taking the measurements By all accounts, we're at the tipping point for a major shift in the way buildings are designed and built. Whether the motivation is rooted in marketing or a moral sense (or both), architects have begun to rally around their power to adjust the global thermostat. And to his credit, Mazria has kept things clean and simple by basing the targets on a common measurement: the amount of BTUs a building uses per square foot, with reductions benchmarked against the EPA Target Finder's averages for different building types. (Its values are calculated from the Commercial Buildings Energy Consumption Survey (CBECS)—a baseline agreed upon by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), The American Institute of Architects (AIA), and the U.S. Green Building Council (USGBC).) But hitting those goals takes some homework.

Rob Brennan, AIA, of Baltimore-based Brennan + Company Architects, started using green specs five years ago and does a “green plan” for every project. As a result, he believes he's well on the way toward hitting the 60 percent target. Verifying those numbers is the more difficult task, however, and the ability to take quick, accurate measurements in the design phase will become even more critical as the targets progress. Brennan recently identified a mechanical engineer who does energy modeling and is offering the service as an option for clients, but money is an obstacle. “We're climbing the ladder; some clients are open to it, others not at all,” he says. “The 2030 Challenge is a noble cause; it's made people aware of what needs to be done, and quickly. Our effort in the next year will be to quantify our projects' energy use to get to these more aggressive numbers.”

If anyone knows how to balance BTUs and budget, it's long-time environmentalist David Arkin, AIA, Arkin Tilt Architects, Berkeley, Calif. But even he agrees that running the numbers is hard work. It's something architects aren't trained to do, and it's difficult to find energy-savvy engineers willing to work on a small scale. That's why he hired recent architecture school graduate Dan Johnson, LEED AP, to do the math. Johnson interned at Spokane, Wash.-based Integrated Design Lab, which conducts sustainability studies. “We're skeptical of the results we get from energy consultants,” Johnson says. “Maybe they don't understand the design entirely. I like doing the calculations right in front of me, so I know what all the assumptions are. For a lot of stuff I just use pencil and paper. Calculating something by hand will keep you moving faster and require less investment in time.”

Because BTU averages for small residential projects aren't readily available, Arkin Tilt measures its work against California's Title 24 energy code, aiming for at least a 60 percent reduction. For energy modeling, the architects use DOE–2 software and also ENERGY–10, which is oriented toward smaller buildings. “It's only recently that this issue has penetrated single houses,” Johnson says. “A lot of the mechanical systems, such as radiant floors, aren't even included in the software, so we have to hack that. As more residential architects turn to energy software, manufacturers are responding, but they're slow to develop new products.” And the fancier 3-D modeling programs aren't necessarily better, he believes. “The simpler programs that simulate your building as a dumb box are faster to use, and I don't think the numbers are any less accurate,” Johnson says. “Plus, if we change anything during construction, the greater accuracy of the model we use in design doesn't pay.”

For Arkin, who's been using passive solar strategies since day one of his 11-year-old practice, heeding the 2030 Challenge has meant paying far more attention to the building envelope, selecting the most efficient windows and weather-stripping details, for example. He's also considering monitoring finished projects for a year, using the feedback to fine-tune his specs. “I do think the 2030 Challenge is going to succeed because it's relatively straightforward,” he says. “You're given a number of ways of accomplishing it, and the tools are out there.”