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<\/a><\/p>\nSantorini\u2019s whitewashed buildings at dusk.<\/p>\n
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\u2019s 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\u2019s picturesque chimney-like badgirs or wind catchers<\/a> have helped desert dwellers stay cool for millennia, for example, and in the tropics, Malaysians have long engineered their homes on stilts<\/a> to avoid floods and let a breeze in.<\/p>\n Many homes and cities in Europe are still living as if AC<\/a> 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<\/a> tore through western Europe last week, killing at least 1,300 people<\/a>, it has become increasingly clear that old-world buildings are not cooling enough on their own for our new world of heat<\/a>.<\/p>\n As a similar heat dome<\/a> 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\u2019s 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\u2019s day.<\/p>\n Clearly, climate change has, to some extent, vindicated America\u2019s hyperreliance<\/a> on the AC. Unlike in Europe, with its suddenly vulnerable<\/a> passive cooling systems<\/a> that kept things temperate back when weather used to be normal<\/a>, 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<\/a>.<\/p>\n But the roaring, life-saving success of the AC has also embedded a profound vulnerability: the moment the power<\/a> goes<\/a> out<\/a>, as it\u2019s prone to do in a heat wave \u2014 or that electricity bills get too onerous, which tends to happen when the AC is cranked \u2014 the nation\u2019s cold-blooded buildings convert into furnaces.<\/p>\n In most conventional American houses, if you \u201close power in the middle of an extreme heat wave or in a blizzard, you\u2019ve got hours before you need to get out,\u201d said Alexander Gard-Murray, executive director of Passive House Massachusetts, a group that encourages the state to build naturally cooler buildings \u2013 or \u201cpassive houses\u201d \u2013 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\u2019t build facing the sun, plant trees, add an awning, and replace heat-radiating asphalt driveways with gravel.<\/p>\n 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 \u2014 which, by the way, could cut your electricity bills in half<\/a> \u2014 at a time when America\u2019s electrical grid is desperately straining to keep everything online. Most importantly, it ensures that \u201cif something does go wrong, if the power goes out,\u201d said Gard-Murray, \u201cyou\u2019re still going to be okay.\u201d<\/p>\n Air conditioning reshaped how America builds for heat<\/strong><\/p>\n American homes used to reflect the cities they were built in. Cool air flowed beneath the floorboards of New Orleans\u2019 breezy raised shotgun houses. Boston\u2019s winter winds met the saltbox house\u2019s long, sloping roofs, and Pueblo tribes used thick blocks of mud to build adobe homes that withstood the desert\u2019s daily fluctuations.<\/p>\n Shotgun homes in New Orleans. Bryan Tarnowski\/Bloomberg<\/p>\n A saltbox house in Masachusetts History Archive\/Universal Images Group<\/p>\n But in 1947, an engineer named Henry Galson transformed how America builds with his invention of \u201cthe people\u2019s air conditioner<\/a>,\u201d a low-cost AC unit \u2014 until then, a luxury item \u2014 snug enough to nestle into a residential window. With millions of service members, then returning from World War II, the nation needed more housing, and it needed it fast. Cheap air conditioning allowed builders more flexibility to mass-produce the suburbs that sprawled out<\/a> as a solution to America\u2019s post-war housing crisis \u2014 even in hot climates like the Sunbelt.<\/p>\n Air conditioning made large swaths of the country newly habitable, fueling the spectacular growth of many now-flourishing metropolises across the American South and Southwest. In less than a century, the AC transformed blisteringly hot Phoenix from a small desert town, population 65,000, into the fifth-largest city<\/a> in the country.<\/p>\n At the same time, as the AC became ubiquitous in America, \u201cmany architects stopped designing buildings for their specific context,\u201d said Sonia Chao, associate dean of architecture at the University of Miami and author of Calibrating Coastal Resilience. \u201cWhat we have today are buildings in South Florida that look a lot like the buildings being built in California or Arizona\u201d or more temperate climates, when in fact \u201cwe really shouldn\u2019t be building in the same ways.\u201d<\/p>\n Most homes in South Florida once sat atop crawl spaces that protected them against floodwaters and let in a breeze to naturally cool the rooms above, said Chao. But many local buildings are now built directly atop concrete, meaning that \u201cas the earth itself gets warmer,\u201d the homes above absorb the heat too.<\/p>\n Of course, if you blast your AC high enough, you probably won\u2019t feel it. And, for decades, that gave American developers tacit permission to pare down the elements like thick masonry<\/a>, high ceilings<\/a>, shaded porches<\/a>, and window shutters<\/a> that once naturally kept us cool in favor of cheap drywall and easier-to-construct boxy floor plans that helped them cram sprawling tracts of readymade starter homes across suddenly bustling desert cities such as Phoenix and Albuquerque. They cleared trees and poured asphalt, churning out decades\u2019 worth of leaky, heat-absorbent neighborhoods. But it didn\u2019t matter \u2014 so long as the AC kept running.<\/p>\n The problem with America\u2019s hyperreliance on the AC<\/strong><\/p>\n AC proved transformational to American life in profoundly positive ways, stretching the boundaries of where one can comfortably live and greatly reducing extreme heat as a public health threat. The problem is, if for whatever reason, the AC is not running, many American homes now become immediately and extraordinarily exposed. \u201cWe all like to believe that the grid is safe and stable,\u201d said Katrin Klingenberg, executive director of Phius, which sets standards for passive homes constructed in the US. \u201cBut it\u2019s actually way more vulnerable than we all think.\u201d<\/p>\n Researchers estimate that if Phoenix were to experience a two-day blackout<\/a> during one of its regular heat waves \u2014 knocking out air conditioning citywide \u2014 it would quickly kill 12,800 people, or roughly 1 percent of the population, while a full half of the city would require emergency medical care.<\/p>\n Arizonans will always need AC to stay safe from the heat, but they could be far more resilient to temporary lapses if their homes and neighborhoods were better designed to stay cool without it. If Phoenix planted enough trees to shade half of its streets \u2014 which would be enough to lower the city\u2019s temperature<\/a> by at least a few degrees\u2014 27 percent fewer residents would die in such a blackout, according to the study. If every building installed a \u201ccool roof\u201d \u2014 simply painting it with a white material to better reflect sunlight \u2014 then the death toll would plummet by 66 percent.<\/p>\n In Arizona, mobile home residents are especially vulnerable to heat waves. Patrick T. Fallon\/AFP<\/p>\n This is not just a thought experiment. Driven by extreme weather and an aging electrical grid, the number of power outages in the US<\/a> has doubled over the past two decades. After Hurricane Beryl knocked out power for millions in Texas in 2024, at least dozens \u2014 and possibly hundreds<\/a> \u2014 of people died from heat-related causes, meaning the outage may have been deadlier<\/a> than the storm itself.<\/p>\n \u201cIt overcomes you really fast,\u201d said Patricia Solis, executive director of the Knowledge Exchange for Resilience at Arizona State University, which focuses on Maricopa County, where hundreds of people<\/a> die from heat-related causes each year, many inside their own homes, their air conditioning broken, turned off, or unplugged.<\/p>\n One of them was Stephanie Pullman<\/a>, a 72-year-old who died in Phoenix in 2018, a day after her electricity was cut off over a $51 unpaid bill. Another was Patricia Miletich, a 70-year-old with memory issues, whose busted AC was blowing hot 110+ degree air into her RV when she died in June 2024. Upwards of a quarter of Arizonans<\/a> who succumb to heat inside their homes live in mobile houses, structures whose thin walls, poor insulation, and cramped concrete quarters make them especially expensive to cool with AC, and especially deadly without it.<\/p>\n Because this extreme heat is \u201cgoing to happen increasingly to more and more of us around the world,\u201d Solis warned, we have to \u201cmake it a part of the way that we build our environments, that we build our homes, that we rebuild our homes.\u201d<\/p>\n How to build a home for the climate we actually have<\/strong><\/p>\n It\u2019s not as hard or expensive as you might think to build a cooler home, one that does at least some of the work needed to keep things more comfortable in extreme temperatures.<\/p>\n \u201cIt\u2019s not about doing extraordinary things; it\u2019s about doing ordinary things extraordinarily well.\u201d<\/p>\n \u2014 Alexander Gard-Murray, executive director of Passive House Massachusetts<\/p>\n Something as simple as facing an RV away from the sun, adding an awning or garden trellis, or installing vinyl skirting around the foundation to prevent hot air from coming up through the floor, could make a mobile home safer<\/a> to be in if the power goes out, says Solis. And even in less catastrophic conditions, these age-old adaptations would make an AC unit cheaper to run. When she began her work, some mobile home park owners sought to outright forbid residents from adding cooling features like a small window garden for purely cosmetic reasons. Solis and her team later helped pass a law outlawing such practices<\/a>.<\/p>\n Even earning the gold standard of building cooler buildings \u2014 a \u201cPassive House\u201d certification from Phius \u2014 isn\u2019t \u201csome space-age, super advanced crazy thing,\u201d said Gard-Murray, of Passive House Massachusetts. \u201cIt\u2019s not about doing extraordinary things; it\u2019s about doing ordinary things extraordinarily well,\u201d he said, like making sure your walls are airtight and thick enough to act as a buffer against outside temperatures.<\/p>\n If most American buildings absorb heat like a plastic water bottle left out in the sun, a passive house is built like a thermos, keeping things relatively temperate regardless of the temperature outside. To illustrate that, a group of architects once built two miniature houses<\/a>, one according to normal building codes and the other like a passive house, plopped them in a park in New York City, and filled both with 1,800 pounds of ice. One month later, the mini passive house had 40 percent of its ice left, while the other one had only 7 percent.<\/p>\n You can imagine how much safer that makes you if your AC ever goes out, and makes it up to 90 percent less energy-intensive to run \u2014 enough to cut your utility bills in half \u2014 when it\u2019s on. \u201cIf we\u2019re much more intentional about insulating the property, the heating and cooling systems have to do a lot less work,\u201d said AJ Patton, founder of the Chicago-based developer 548 Enterprises, which is currently building Chicago\u2019s largest-ever Passive House-certified affordable housing complex.<\/p>\n \u201cToo often we\u2019ve used sustainable technologies as a luxury item,\u201d said Patton, but the biggest benefits to these homes are for lower-income households who could really use the savings on their bills or are more vulnerable to having their power cut off.<\/p>\n As of now, only about one percent of homes being built in the US are built according to passive standards. One might assume that building such a sensible, sustainable, and safer home must be prohibitively expensive, or else it would be much more common. After all, who doesn\u2019t want a significantly lower utility bill, all other things being equal? But in reality, at least in Massachusetts \u2014 where passive designs are now the mandatory norm in many cities \u2014 a survey found that such buildings only cost as little as two to three percent more<\/a> than conventional buildings.<\/p>\n Equally important in a country with a notorious housing shortage, the municipalities in Massachusetts that have opted into more stringent requirements continue to build new homes at a faster clip<\/a> than those that haven\u2019t, and they approved more new housing permits after the change. There could be a lot of factors at play in those differences, but at the very least it shows that requiring strict standards in this case might not, as some skeptics fear, \u201ccrash our housing production,\u201d Gard-Murray said.<\/p>\n The real reason why these building techniques don\u2019t happen more often comes down to a lack of awareness, experts told me, along with the fact that the biggest financial benefits are for whoever pays the utility bill, not the developer who has to pay the upfront costs. It doesn\u2019t help either that the Trump administration has cut or let expire tax credits<\/a> that helped defray the extra costs of energy-efficient buildings. Some projects like Patton\u2019s lost out on $300,000 in expected incentives in real time.<\/p>\n \u201cThe moronic government policies of the last 18 months are not helping us,\u201d said Mark Ginsberg, a founding partner of Curtis + Ginsberg Architects, which has completed about 25 multi-family passive projects in New York City, most of them affordable or supportive housing.<\/p>\n\n
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