I grew up in the world’s coldest city without central heating. Here’s what the world can learn from us

On winter mornings in Harbin, where the air outside could freeze your eyelashes, I would wake up on a bed of warm earth.

Harbin, where I grew up, is in northeast China. Winter temperatures regularly dip to -30°C and in January even the warmest days rarely go above -10°C. With about 6 million residents today, Harbin is easily the largest city in the world to experience such consistent cold.

Keeping warm in such temperatures is something I’ve thought about all my life. Long before...