Not as easy as it looks: The Applied Research and Development Building, at Northern Arizona U. (Photo courtesy Northern Arizona U.)

Getting a platinum certification in the Leadership in Energy and Environmental Design program is not easy. Getting the highest-rated LEED building in academe, as Northern Arizona University did, is quite a feat indeed.

But of the 60 points (of a possible 69) that Northern Arizona’s Applied Research and Development building racked up for sustainable materials and green building practices, none was tougher than a point found in the miscellany category at the bottom of the LEED checklist: It’s a point for using high-volume fly-ash concrete.

Fly ash is a byproduct of coal-burning power plants. It can be substituted for Portland cement to reduce concrete’s carbon footprint. (It takes a lot of energy to produce Portland cement.) Fly-ash concrete comes with another benefit: It’s stronger than conventional concrete when cured.

But curing—a chemical process in which cement hardens as it reacts with moisture in the concrete mix—is part of the problem. Fly ash retards the curing process — it has a 56-day curing cycle, versus a 28-day curing cycle with conventional concrete.

Because the new building’s foundations were poured in summer and fall, the vertical columns had to start going up in the middle of winter, when it was 15 degrees outside. “We had to protect the columns so the moisture in the concrete wouldn’t freeze,” which would ruin the pour, says Paul Dufek, the project manager who worked on the building.

“So we went out and bought every electrical heating blanket in Flagstaff,” he says. “For a few weeks, you couldn’t get an electric heating blanket in Flagstaff because they were all here.” Workers wrapped three or four blankets around each column for up to a week — enough time to allow the concrete to set up. Mr. Dufek says that concrete associations from across the country have come to tour the building and see what many in the industry thought was impossible.

Incidentally, concrete is a major part of the heating and cooling system in the building, which was designed by Burns Wald-Hopkins Architects. Concrete inside the building acts as a thermal mass — that is, it stores heat as the sun beats on it through the long windows on the south side of the building. Then it releases that heat at night when the desert climate gets cold. In the summer, shades on the windows keep the sun off the concrete; that cold mass helps keep the building cool.

Mr. Dufek says that during construction in the winter the building was able to maintain a steady 60 degree temperature with no supplemental heat. The building’s passive heating and cooling systems help to make it about 82 percent carbon neutral — astounding when you consider that one floor of the building is almost all laboratory space, which hogs energy. —Scott Carlson

It’s a wrap: Workers covered columns with electric blankets to keep them from freezing in a high-altitude Arizona winter. (Photo courtesy Northern Arizona U.)