What Will It Take to Make Buildings Carbon Neutral?

If cities are going to curb the rise of global temperatures to less than 2 degrees Celsius, they’ll have to address the single largest contributor, by sector, to their carbon footprint: buildings. Buildings account for roughly 50 percent of a city’s total carbon emissions, and 70 percent in major cities like London, Los Angeles, and Paris.

The ultimate goal, as laid out by the World Green Building Council at COP 21 in Paris in 2015, is that by 2050—when 68 percent of the world’s population is projected to live in urban areas—all buildings will only use as much energy as they generate. And to get there, a group of large cities is first tackling a closer target. Last month, the mayors of 19 cities—including New York, London, Tokyo, and Johannesburg—declared that they will enact policies and regulations that will make all new buildings carbon neutral by 2030.