Wait a minute. Did the mayor of New York threaten to ban glass skyscrapers? Bill de Blasio certainly gave that impression during a press conference on Earth Day: “We are going to introduce legislation to ban the glass and steel skyscrapers that have contributed so much to global warming,” he proclaimed. “They have no place in our city or on our Earth anymore.”

De Blasio’s stated motivation is certainly correct: The planet faces an environmental disaster due to excess greenhouse gas emissions, and buildings are major producers. An inventory of 2015 emissions [PDF] in New York found that buildings accounted for 67 percent of the year’s total. But many building technologies contribute to the problem, not just one envelope type. A ban on the glass curtainwall seems like an ill-advised solution that could, among other things, actually limit the development of sustainable design techniques.

As it turns out, de Blasio was trolling—sort of. After dropping the ban bomb, he offered a clarification: “If a company wants to build a big skyscraper, they can use all the glass [they want], if they do all the things needed to reduce the emissions. But putting up monuments to themselves that harm our Earth and threaten our future—that will no longer be allowed in New York City.” Fair enough.

At the press conference, the director of the Mayor’s Office of Sustainability, Mark Chambers, reiterated that there would be, in fact, no ban on glass. Instead, the goal is to increase large and tall buildings’ energy efficiency and reduce their carbon footprints.

Curiously, just a few days before, the City Council had passed legislation to reduce greenhouse gas emissions from large buildings by 40 percent by 2030, as part of a larger Climate Mobilization Act.

So why did de Blasio bother? I suspect he was performing a bit of political theater, wrapping a rational regulatory goal to reduce emissions in extreme rhetoric, and piggybacking on the notoriety of the proposed Green New Deal in Congress. By that standard, the ploy worked: Here I am, writing about it.

Unfortunately, de Blasio pushed questionable policy, and that calls for a response. Outright bans of specific materials or technologies often make clumsy, counterproductive tools. Where climate is concerned, government should establish where we need to go, but shouldn’t dictate how to get there. Hopefully New York—and any other entity pursuing reductions in emissions and embodied carbon—will instead pursue goals-based strategies that set targets and promote best practices. I say this not because of some ideological opposition to government intervention, but because we need all the good ideas we can get.

Over the past decade or so, the sustainability movement has helped kindle an amazing resurgence of technology in architectural practice and education, and it would be criminal to limit the possibilities. After decades of spectacular form-making, the pendulum is swinging in the opposite direction. Passion for modeling complex curves is giving way to the necessity of modeling building performance. While both can be profoundly creative acts, at this fragile moment in ecological history, we should encourage the latter, pragmatic sort of innovation—and vehemently oppose obstacles to it.