--- title: AC Units Are Stifling More Sustainable Ways of Cooling Homes description: In the U.S., it's still easier for developers to pass on the cost of cooling homes to residents rather than invest in passive design. canonical: https://time.com/7305482/air-conditioning-passive-homes-sustainable-cooling/ author: Sam Bloch article:opinion: false article:content_tier: free article:published_time: 2025-07-28T11:00:00.000Z article:modified_time: 2026-03-11T01:30:57.921Z article:section: Climate og:title: AC Units Are Stifling More Sustainable Ways of Cooling Homes og:description: In the U.S., it's still easier for developers to pass on the cost of cooling homes to residents rather than invest in passive design. og:url: https://time.com/7305482/air-conditioning-passive-homes-sustainable-cooling/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltfaea0fe7d283826f/6998c89f1f6709fa75f569b5/air-conditioning-passive-housing-sustainable-design-extreme-heat-shade.jpg?branch=production&width=1024&quality=75&auto=webp&crop=16:9 og:image:width: 1024 og:image:height: 576 og:image:alt: Northeastern US To Swelter In First Heat Wave Of The Season og:type: article twitter:card: summary_large_image twitter:title: AC Units Are Stifling More Sustainable Ways of Cooling Homes twitter:description: In the U.S., it's still easier for developers to pass on the cost of cooling homes to residents rather than invest in passive design. twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltfaea0fe7d283826f/6998c89f1f6709fa75f569b5/air-conditioning-passive-housing-sustainable-design-extreme-heat-shade.jpg?branch=production&width=1024&quality=75&auto=webp&crop=16:9 ---  # AC Units Are Stifling More Sustainable Ways of Cooling Homes > Sponsored content. 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Future Proof is TIME's weekly climate and energy newsletter, written by senior correspondent Justin Worland. It connects the energy transition to the decisions reshaping business, technology, policy and markets. #### Where can I follow the energy transition as a business story? Future Proof covers climate and energy as an economic and business story rather than only an environmental one. It publishes every Friday and is free at time.com/newsletters. #### Who writes Future Proof? Justin Worland, a senior correspondent at TIME and an award-winning climate journalist, writes Future Proof. #### Is Future Proof free? Yes. Future Proof is free at time.com/newsletters. by [Sam Bloch](https://time.com/author/sam-bloch/) ## Sam Bloch Jul 28, 2025 11:00 AM UTC  Air conditioning units installed in windows at an apartment complex in Hyattsville, Maryland, on June 17, 2024. Air conditioning units installed in windows at an apartment complex in Hyattsville, Maryland, on June 17, 2024. Graeme Sloan/Bloomberg—Getty Images by [Sam Bloch](https://time.com/author/sam-bloch/) ## Sam Bloch Jul 28, 2025 11:00 AM UTC Americans are too reliant on air conditioning, an energy-hungry technology that worsens climate change. Artificial [cooling](https://time.com/7297693/heat-wave-air-conditioning-climate-guilt/) already accounts for 10% of globalheat-trapping greenhouse gas emissions, and the share could double in the next 25 years. Yet many of us live in homes that would be stuffy and [uncomfortable without AC](https://time.com/7295554/efficient-air-conditioning-heat-wave/), and in extreme conditions turn dangerous. It’s not an overstatement to say that the pollution we generate for cooling inside is burning the planet outside. But we have a sustainable solution to this problem in the form of passive housing, a new kind of low-energy architecture governed by old design philosophies. Passive houses consume only a quarter of the energy that is needed to warm a typical American house in the winter and cool it in the summer. In fact, some passive houses don’t need air conditioning at all. Yet at present, it accounts for less than 1% of new American construction in the past decade. Why isn’t it more popular? Passive houses embody what is known in energy efficiency circles as the split incentive problem, or an investment whose benefits do not accrue to the investor. The vast majority of American homes are built by developers and sold to someone else, and the vast majority of those developers are not financially incentivized to minimize their future occupants’ need for cooling, heating, and other utilities. In fact, the largest developers resist efforts to increase the home insulation needed to improve energy efficiency. But most developers aren’t Jeff Stern, a brainy, 59-year-old architect who lives in a passive house of his own design in Portland, Oregon. From the street, the two-story, 1,965-square-foot house looks clean and modern: two conjoined boxes, clad in brown cedar and accented with Mondrianesque red stripes. The mid-century aesthetic camouflages the traditional thermal design. **Read more:** [_Air Conditioning Will Not Save Us_](https://time.com/6199353/air-conditioning-will-not-save-us/) A principal consideration is solar orientation. Stern’s house faces south, admitting sun for natural warmth in Portland’s cool winters. In the summer, Stern relies on metallic window shades, installed outside the house, to keep that heat at bay. Another consideration is insulation: Lots of it, easily twice the code minimum, to emulate the thick walls of a mudbrick hut and slow heat transfer. The foundation, walls, and roof all fit together to create an airtight seal. And natural ventilation is key. In the summer, when the sun goes down, Stern opens the windows to bring in the evening breeze. “Night dumping,” he calls this process of natural cooling. Not long after he wakes in the morning, he scoots around the house, closing the windows and the shades to seal in the cool air before the outdoor temperature rises. In fact, during the Pacific Northwest’s lethal 2021 heat dome, when the official air temperature in Portland reached a breathtaking high of 116 degrees, the temperature in Stern’s passive house never ticked above 84\. That’s not what most Americans consider comfortable, but during a killer heat wave, it is safe. “Light sweating mode,” Stern laconically recalled, as he and his wife sauntered around the house in shorts.  Stern had a unique opportunity to build his own low-energy home and eventually recoup the costs of his upfront investments in the form of small utility bills. But he experiences the split incentive problem when he designs other peoples’ homes. Years ago, he was hired to design a four-story, 23-unit apartment building for a developer in Portland. On the southern exposures, Stern called for wood shutters to slide on a track outside the windows, like a barn door. For most of the year, the shades would be out of the way, but in the summer, he imagined residents could crank open their casement windows, reach outside, and slide the shutters across the glass. But early on in construction, the developers began to worry about the durability of the external shades and backed out. What the tenants got instead were window ports to install their own AC units. Instead of paying more up front to save energy, the developer opted to pass the costs of cooling on to the future tenants. From a business perspective, the decision of developers to cut corners and not to invest in insulation, shading and other energy-saving measures makes sense. But the impact of decisions they make to protect their individual bottom lines affects all of us in the future, in the form of more and more energy that will be needed to keep those buildings cooler and cooler as temperatures continue to rise. It is this understandable self-interest that has prevented passive housing from reaching the masses. To cut through this knot, Americans need stronger building codes that mandate higher energy-efficiency standards, and developers need stronger financial incentives to build climate-resilient homes. We have reasons to be optimistic. **Read more:** [_How to Keep Your Home Cool in Extreme Heat_](https://time.com/6295911/how-to-keep-house-cool-extreme-heat/) Since Stern finished his passive house in 2013, such policies and incentives have boosted passive house construction in states such as New York, Massachusetts, Pennsylvania, and Colorado, where political leaders are committed to reducing the carbon emissions of the building sector. To achieve these goals, they have not only beefed up their building codes but also awarded tax breaks and direct cash incentives to homebuilders who meet passive standards. Because of their unusual requirements, a passive house, apartment, or office can cost 3% to 5% more to build than a conventional structure. These states are offsetting the cost of that construction through government support. Currently, there are about sixteen thousand passive house apartments in the works nationwide. If every state in America strongly committed to reducing energy and increasing climate resilience, then passive housing could one day be as popular in the United States as it is in the European Union, where member countries are commanded to reach zero emissions in new buildings by 2030 and in existing ones by 2050\. This mandate has made passive house construction all but essential in many countries. The Continent boasts many thousands more passive houses, apartments, and offices than the United States, and while most are new builds, some are also retrofitted old stock. “I move into a building, and it’s marketed as a luxury building,” said Alexandria Ocasio-Cortez, the congresswoman who represents New York City’s outer boroughs in Washington, D.C. “It’s an efficient building, it’s clean, it has public space, it has a rooftop garden.” A few months after she first introduced a Green New Deal resolution in 2019 that set a long-term goal of sustainable and affordable housing for every American, Ocasio-Cortez returned to Queens to open eight stories of passive house apartments for the elderly, many of whom were formerly homeless. “I do a tour with one of the seniors,” she continued, “and it looks just like my apartment.” She was stunned. Her visit occasioned a question: How could safe, dignified, and environmentally responsible housing be available for everyone? In part, through passive housing. The technical prerequisites for the world that she and others fight for are already here. _This is an edited excerpt from the book_ SHADE: The Promise of a Forgotten Natural Resource _by Sam Bloch. Copyright © 2025 by Sam Kahn Bloch. Publish by Random House, an imprint and division of Penguin Random House LLC. 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