The decision of Greek islanders to coat their cliffside homes, churches, and pathways in pearly white paint was driven by practicality rather than aesthetics.
Just as a white tunic can keep one cool on a sunny day, painting buildings in white helps ancient islands reflect heat back into space, reducing absorption into structures. Before the advent of air conditioning, people in warm climates used similar methods: Iran’s chimney-like badgirs helped desert dwellers stay cool, while Malaysians built homes on stilts to avoid floods and allow air circulation.
In Europe, many homes and cities still operate as if air conditioning had never been invented, relying on thick shutters and ventilated courtyards to maintain airflow and shade. However, following a deadly heat wave that claimed at least 1,300 lives in western Europe last month, it is evident that traditional buildings are insufficient to combat the new heat extremes.
Conversely, the U.S., a nation reliant on air conditioning since World War II, faces a different issue. American buildings, designed with AC in mind, often lack natural heat defenses. The advent of air conditioning enabled the construction of large homes, malls, and glass office towers that, like cold-blooded lizards, absorb heat during heat waves.
In some respects, climate change has justified America’s heavy reliance on air conditioning. Unlike Europe, where passive cooling systems have become vulnerable, the U.S. can withstand heat as long as the AC is functional. Since the 1960s, the risk of heat-related deaths in America has dropped by 80 percent due to air conditioning.
Yet, this dependence on AC poses significant risks. Power outages during heat waves can turn buildings into furnaces, as they lack natural cooling mechanisms. Moreover, high electricity bills, often incurred during heat waves, can be burdensome.
In conventional American homes, losing power during extreme conditions means evacuation within hours, according to Alexander Gard-Murray, executive director of Passive House Massachusetts. However, implementing common-sense measures, such as planting trees, adding awnings, and using gravel instead of asphalt, can enhance natural cooling. These strategies, while not eliminating the need for AC, can reduce its workload, potentially halving electricity bills.
Air conditioning reshaped how America builds for heat
Historically, American homes were designed in harmony with their environments. New Orleans’ raised shotgun houses allowed cool air to circulate, while Boston’s saltbox houses withstood harsh winds. The Pueblo used thick mud blocks for insulation against temperature fluctuations.
However, in 1947, engineer Henry Galson revolutionized building practices with his invention of an affordable air conditioning unit. This innovation facilitated rapid housing development to accommodate post-war growth, especially in hot regions like the Sunbelt.
Air conditioning made vast areas of the U.S. livable, transforming cities like Phoenix into major urban centers. In less than a century, Phoenix grew from a small town to the fifth-largest city in the country.
Despite its widespread adoption, air conditioning led to a decline in context-specific building designs. Sonia Chao, associate dean of architecture at the University of Miami, notes that many buildings in South Florida resemble those in California or Arizona, despite differing climates. Buildings, once elevated to allow airflow, are now built directly on concrete, absorbing more heat.
While air conditioning effectively masks the heat, it allowed developers to overlook natural cooling designs like thick walls and shaded porches. Instead, they opted for cheaper materials and boxy designs to quickly construct homes in growing cities like Phoenix and Albuquerque.
The problem with America’s hyperreliance on the AC
Air conditioning has significantly improved American living standards by mitigating heat-related health risks. However, in the event of power failures, many homes become dangerously vulnerable. Katrin Klingenberg of Phius highlights the grid’s vulnerability, noting that a two-day blackout during a Phoenix heat wave could result in thousands of deaths.
Enhancing natural cooling in homes and neighborhoods can mitigate heat risks. Shading half of Phoenix’s streets could reduce heat-related deaths by 27%, while cool roofs could cut fatalities by 66% during blackouts.
Power outages in the U.S. have doubled over the past two decades, exacerbated by extreme weather and an aging grid. After Hurricane Beryl in 2024, the ensuing power failure in Texas led to numerous heat-related deaths, possibly exceeding those caused by the storm.
Patricia Solis from Arizona State University highlights the rapid impact of heat, which claims hundreds of lives annually in Maricopa County, many from homes with malfunctioning or absent air conditioning.
Tragically, people like Stephanie Pullman and Patricia Miletich have died due to heat-related issues in their homes, illustrating the vulnerability of mobile homes with poor insulation.
Solis emphasizes the need for integrating heat resilience into building practices globally, as extreme heat events become more common.
How to build a home for the climate we actually have
Creating a more heat-resilient home need not be complex or costly. Simple strategies, like orienting an RV away from the sun or adding an awning, can enhance comfort and safety during power outages.
Solis notes that some mobile home park owners have resisted such adaptations for aesthetic reasons, but her team has helped pass laws to protect residents’ right to implement them.
Achieving Passive House certification, the gold standard for energy-efficient buildings, is about executing basic principles well, such as ensuring walls are airtight and well-insulated.
A passive house acts like a thermos, maintaining a stable temperature and reducing energy usage by up to 90%, which can significantly lower utility bills. AJ Patton of 548 Enterprises is developing Chicago’s largest Passive House-certified affordable housing project, emphasizing the value of energy savings for low-income households.
While only a small percentage of new U.S. homes meet passive standards, Massachusetts has shown that building passive homes costs only slightly more than conventional ones, disproving the assumption that they are prohibitively expensive.
Massachusetts municipalities adopting stricter building codes continue to construct homes at a faster rate, dispelling fears that higher standards would hinder housing production, according to Gard-Murray.
Experts attribute the limited adoption of passive building techniques to a lack of awareness and the financial benefits accruing to utility bill payers rather than developers. The expiration of tax credits for energy-efficient buildings further complicates matters, as highlighted by Mark Ginsberg of Curtis + Ginsberg Architects.
Ginsberg criticizes recent government policies for impeding progress, noting that climate change denial remains prevalent. With a heat wave threatening millions, enhancing our AC systems could not come soon enough.
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