When it gets too hot, the human body starts to cook. At 89.6 degrees Fahrenheit you begin sweating to maintain your core body temperature; by 95 degrees, you’re no longer able to shed heat through radiation alone, relying entirely on the mechanism of water evaporating from your skin. Once it’s 104 degrees out, your body stops working the way it should. By 120 degrees, if you don’t take drastic measures to cool and hydrate yourself immediately, you’re dead.
It’s still unusual for most parts of the U.S. to reach 120 degrees (though humidity and “wet bulb” temperature can reduce the effectiveness of sweating, making much cooler temperatures dangerous, too). The bad news, though, is that it’s not the outdoors you necessarily need to be all that worried about. Most people who die in heatwaves die inside.
Manufactured homes, also called mobile homes, are particularly lethal in extreme heat. During the 2021 Pacific Northwest heat dome, 20% of the 96 people who died in Oregon lived in such housing, according to an analysis by The Oregonian. In Phoenix in 2024, a full quarter of heat-related deaths occurred in mobile home parks, trailers, and RVs, which make up only 5% of the Valley’s housing stock. In Pima County, the rural region that encompasses Tucson, the share of deaths in the homes was even higher.
And yet last week, the House of Representatives approved a bill that could prevent the adoption of regulations that would help prevent future heat-related deaths in manufactured homes. The vote was the culmination of a nearly decade-long fight over who should regulate the construction of manufactured homes, which are crucial to solving the housing crisis and the primary route to low-income homeownership. It also lies at the crux of the debate over building out quick, cheap homes — the industry’s preference — versus investing in resilient construction practices with an eye on a hotter future.
H.R. 5184 looks, on its surface, like a common-sense affordability bill. Energy standards for manufactured homes have traditionally fallen under the purview of the Department of Housing and Urban Development, which has not updated the regulations since 1994. In 2007, on a bipartisan vote, Congress passed a law directing the Department of Energy — which has more expertise in energy efficiency than HUD — to set new standards for manufactured homes, which the department (finally) issued in 2022, and which focus on increasing insulation and reducing air leaks.
Slammed as costly “red tape,” the standards were repeatedly held off from going into effect. H.R. 5184 is meant to ensure they never will. Indiana’s Republican Representative Erin Houchin, who authored the bill, claims that the regulations would increase the upfront cost of manufactured homes by “$10,000 to $15,000” over the existing HUD standards. (The DOE’s analysis of the 2022 rule put the added construction cost at between $627 and $4,438, depending on the size of the home and the climate zone.) Proponents of the bill also say it would streamline oversight of manufactured home energy efficiency standards by reverting regulatory authority to HUD alone and excluding the DOE from the rule-making process henceforth.
The bill passed the House with bipartisan support from every Republican and 57 Democrats, the latter group led by Massachusetts Representative Jake Auchincloss. According to the American Council for an Energy-Efficient Economy, which opposes the bill, Auchincloss reportedly used the word abundance “multiple times” when advocating for H.R. 5184 in a private meeting — an apparent reference to the Abundance Agenda, which pushes to remove regulatory roadblocks to progressive goals such as clean energy and affordable housing. (Auchincloss’ team did not respond to a request for comment, though in a letter to his Democratic colleagues, he described housing affordability as “a national problem that we should address with common-sense regulatory reform.”)
But “is the purpose of housing to keep us safe and well and to allow us to actually live our best lives, or is it something else?” Vivek Shandas, the founder of the Sustaining Urban Places Research Lab at Portland State University, asked me. “If housing is set up to keep us out of the elements, then what we’re essentially agreeing to when we’re cutting some of these safety precautions is exposing people to more of the elements,” he said.
The American Council for an Energy-Efficient Economy, an advocacy group, has stressed that H.R. 5184, which preserves the 30-year-old HUD standard, will increase the average annual energy bill by up to $475 for residents of new double-wide homes compared to what they would have paid under the 2022 rules. ACEEE estimates that the break-even point for monthly net savings to recoup the added initial down payment, taxes, and fees for a single-wide home in the South would have been just over a year, and just over four years for a double-wide in the same region. “My hope is that U.S. senators can do math better than, apparently, a majority of their House colleagues and recognize that energy savings significantly exceed the cost of insulation and air sealing,” Mark Kresowik, the senior policy director at ACEEE, told me.
Manufactured home owners already spend an outsized amount of their income on energy costs, and higher energy bills could push residents to avoid turning on their air conditioning during heatwaves, putting their health and potentially their lives at risk. It is “absolutely correct” that H.R. 5184 could result in more mobile home park deaths as a result, Kresowik said.
Cooling manufactured homes can be challenging in general, though. “We’re finding that in some of these [existing] manufactured homes on a 105-degree day, temperatures will be upward of 120, 125 degrees inside,” Shandas said — the threshold of human survival. That’s partially because, unlike site-built homes, mobile homes are often placed on asphalt, which “radiates that heat at night and keeps the temperatures inside the homes up.”
“When the sun rises the next morning,” Shandas explained, “it continues to heat up,” creating a deadly compounding effect.
Even residents who can afford to run an air conditioning unit around the clock at full blast can be in trouble in poorly insulated homes. AC frequently “doesn’t have the horsepower to reduce [indoor temperatures] down to less than 85 degrees, so it often tends to hang around 90 inside on a 100-degree day,” Shandas said. Particularly for the older adult population, some 3.2 million of whom live in manufactured and mobile homes, that is enough to be dangerous.
Esther Sullivan, an expert on manufactured homes at the University of Colorado Denver and the author of Manufactured Insecurity: Mobile Home Parks and Americans’ Tenuous Right to Place, emphasized that H.R. 5184 will affect only the construction of new homes. The most vulnerable live in mobile homes built before the HUD codes instituted in 1976, and which may have as little as an inch of separation between the inside and the outdoors. (One resident Shandas interviewed in Northeast Portland told him that he could tell how fast the wind was blowing when he was inside with his windows closed — it was that drafty.)
As supporters of H.R. 5184 — like the Manufactured Housing Institute, a trade organization that lobbied in support of the bill — point out, most home manufacturers are already voluntarily meeting or exceeding the 2022 DOE standards. (The MHI pointed me toward its statement in support of the bill when I reached out for comment.) Andrew Rumbach, the co-lead of the climate and communities program at the Urban Institute, which does not take an official side for or against the bill, told me that “even if the current HUD standards were not updated and you purchased a manufactured home today, you’re far more safe in an extreme heat event compared to someone who lives in one of those older, potentially dilapidated homes.”
Sullivan also cheered the advancements in new manufactured home construction. Factory-produced housing, even more than site-based homes, can incorporate “extreme innovations in things like energy efficiency,” she said. But H.R. 5184 would be a “major step backward,” she went on, arguing that it won’t even address the housing abundance goals touted by its supporters. “The problem with producing more housing is allowing more housing to be located,” she said. “It’s zoning.” Many suburban and metropolitan areas, for example, forbid mobile home parks from being sited within their borders.
Preventing mobile home deaths in heatwaves will require attention to the existing housing stock, which needs expensive weatherization and park-level infrastructure upgrades, such as shade and collective cooling shelters. “We’ve seen firsthand how replacing aging, energy-inefficient manufactured homes with new, efficient models can create long-term stability for families and entire communities,” Scott Leonard, the Oregon residential project manager of Energy Trust, a nonprofit that helps families make such upgrades to their homes, told me in a statement. Shandas specifically highlighted the need for local, engaged park managers who can check in on residents during extreme heat events. (He also suggested “some kind of indicator or warning that would tell people to leave when it’s hotter inside than outside and go to a cooling center.”)
But new construction needs to be energy efficient as well, so homeowners can afford the operating costs of life-saving AC units during increasingly hot summers. “The bottom line is that people who live in places that have heat waves deserve to live in a home that’s safe from those heat waves,” Rumbach said.
