The fatal flaw in how America handles heat waves

As heat waves strain the power grid, passive cooling can help homes stay safer when the air goes out.

It was not the postcard-worthy aesthetics that prompted Greek islanders to first drench their cliffside-carved homes, churches, and pathways in a thick layer of pearly white paint.

Much like wearing a white tunic on a hot sunny day, painting your house a shade of reflective white is a fine way to keep an ancient island cool, bouncing some of the sun’s heat back into space instead of absorbing it into the structure of the buildings themselves. Before air conditioning existed, people in warmer areas of the world often built with similar techniques in mind: Iran’s picturesque chimney-like badgirs or wind catchers have helped desert dwellers stay cool for millennia, for example, and in the tropics, Malaysians have long engineered their homes on stilts to avoid floods and let a breeze in.

AC has made Americans much safer during heat waves — but it also transformed how the nation builds for heat.

With no built-in protections, many of today’s homes quickly become deadly heat traps if the power goes out or if the AC breaks during a heat wave.

Momentum is growing for passive cooling, which can greatly reduce your need for AC — and your power bill.

Many homes and cities in Europe are still living as if AC had never been invented, relying largely on their thick shutters, ventilated courtyards, and other strategies to encourage shade and airflow. But after a deadly, record-shattering heat wave tore through western Europe last week, killing at least 1,300 people, it has become increasingly clear that old-world buildings are not cooling enough on their own for our new world of heat.

As a similar heat dome now pulses over the eastern US, a nation of AC aficionados faces the inverse of this problem. Since just after the end of World War II, the US has built its homes, schools, and hospitals so thoroughly with AC in mind that most buildings have no built-in defense against the heat at all. The air conditioner made possible America’s cavernous McMansions, megamalls, and frigid glass office towers, engineered like ectotherms, liable to soak up a heat wave like a cold-blooded lizard sprawled out on a rock on a scorching summer’s day.

Clearly, climate change has, to some extent, vindicated America’s hyperreliance on the AC. Unlike in Europe, with its suddenly vulnerable passive cooling systems that kept things temperate back when weather used to be normal, the US can take the heat as long as the air is on. In the aftermath of the AC-enabled postwar housing boom, the likelihood of an American dying on a scorching hot day fell by a staggering 80 percent.

But the roaring, life-saving success of the AC has also embedded a profound vulnerability: the moment the power goes out, as it’s prone to do in a heat wave — or that electricity bills get too onerous, which tends to happen when the AC is cranked — the nation’s cold-blooded buildings convert into furnaces.

Why air conditioning became a cross-Atlantic culture war

In most conventional American houses, if you “lose power in the middle of an extreme heat wave or in a blizzard, you’ve got hours before you need to get out,” said Alexander Gard-Murray, executive director of Passive House Massachusetts, a group that encourages the state to build naturally cooler buildings – or “passive houses” – from the start. Some techniques are state-of-the-art and technologically novel, others are ancient, and still many others are basic common sense: don’t build facing the sun, plant trees, add an awning, and replace heat-radiating asphalt driveways with gravel.

Notably, none of these strategies involve shoving your AC unit out the window. But they can help your air conditioning work a lot less hard — which, by the way, could cut your electricity bills in half — at a time when America’s electrical grid is desperately straining to keep everything online. Most importantly, it ensures that “if something does go wrong, if the power goes out,” said Gard-Murray, “you’re still going to be........

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