Millions of US homes are so overheated they open their windows in the winter. Why?

Nineteenth-century technology is finally being phased out in New York City, but its past is deeply entwined with American history

Until recently, my girlfriend and I lived in a steam-heated apartment in Manhattan. A creaky former tenement building, it had no radiators, just scalding-hot cast iron pipes that punched through the units like fire poles. The pipes terminated a few inches from our ceiling with valves that hissed and sputtered, leaking rusty orange water. And they weren't just heaters, but alarms, clanking like pots and pans every morning around 6.45am when the boiler flipped on in the basement.

This 19th-century technology certainly heated our apartment - but far too well. So every wintertime we would have to throw the windows wide open just to cool down. (My girlfriend enjoyed the contrasting sensations, like ice cream on warm pie. It always felt like a big waste of energy, but it was pleasant in its own old-school New York way," she says.)