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As heat waves get worse, these fixes will help keep your home cool and energy efficient.
July 2023 will almost certainly be declared the hottest month ever recorded, but it is unlikely to hold that record for long. Climate change is making heat waves more frequent, intense, and longer-lasting across the U.S.
Adapting to this hotter future is often discussed at the scale of a city; measured in early warning systems, green spaces, and cooling centers. But there’s also a lot that individual homeowners can do to help their communities and protect themselves.
While the vast majority of American households — some 88% — use air conditioning for relief, homeowners would be wise to consider a variety of additional, “passive” cooling techniques. These are strategies that can keep your home at a safe temperature during a heat wave if the power goes out, an increasingly likely scenario. They will also save you a bit of money on energy bills. In a sense, adapting your home to extreme heat is just another way of thinking about how to make it more energy efficient.
These retrofits also have wider benefits. Since air conditioners work by transferring heat from inside your house outdoors, these fixes can cool down your neighborhood. They’ll cut carbon emissions and air pollution by lowering demand for electricity. If widely adopted, they’ll also help prevent blackouts and could shrink the amount of renewable energy projects that need to be built to replace fossil fuels, alleviating pressure on conservation.
I spoke with Steve Easley, a building science consultant who specializes in energy efficiency, and Shawn Maurer, technical director of the Smart Energy Design Assistance Center at the University of Illinois, about how homeowners should prioritize their options when it comes to passive cooling.
“I always recommend that people do a home energy audit from a certified HERS rater,” Easley told me, referring to the Home Energy Rating System, a nationally recognized system for inspecting and calculating a home’s energy performance. The auditor will tell you how leaky your house is, and how well your roof insulation, windows, and other parts of your house are working to keep out heat, and help you figure out what to attack first. (Easley also recommends getting at least three quotes for any of these solutions, because different contractors bid this work out very differently.)
Below are five things you can do to improve your home’s resilience to heat. Depending on a number of factors — such as where you live, how your house is constructed, and the condition it's in — the mileage you can get out of each of these measures will vary. The good news is that the federal government and many state governments offer tax credits and rebates for most of these solutions. The Inflation Reduction Act created the Energy Efficient Home Improvement tax credit, which offers homeowners up to $1,200 per year to spend on energy efficiency improvements. As part of that, you can claim $150 simply for getting an energy audit.
Maurer said the very first thing he would do to improve the efficiency of a home is to seal up any cracks where air can get in — for example, along the edges of the floors, around the windows, and in the ceiling around light fixtures. “That carries in moisture, heat, and everything from outdoors into the house. It's going to offset any air conditioned air you got inside the house. So air leakage is usually the place we recommend to start,” he said. “And then from there, it's what your budget can handle as far as adding more insulation to your house.”
Insulation comes in a wide range of materials, such as fiberglass and rock wool, blown cellulose, and rigid foam boards. It can be blown into your walls, installed on the floor of the attic, or underneath your roof deck. It’s a jack-of-all-trades when it comes to energy efficiency, since it keeps heat inside in the winter and blocks it from entering in the summer. That means it’s a great option for those in colder climates that also want to prepare their homes for hotter summers.
A 2021 study by a group of researchers at Lawrence Berkeley National Lab modeled the efficacy of a wide array of passive cooling measures in low-income homes in Fresno, California. It found that roof insulation, along with solar-control window films, which we’ll get to in a moment, were the two most effective ways to keep heat from entering the buildings. However, the authors note that roof insulation is an expensive major retrofit, and recommend that it only be done when the roof needs replacement.
A good first step might be finding out what kind of insulation you already have. The most important metric when it comes to insulation is called “R-value,” and the higher the number, the more effective it is. Older homes may have attic insulation as low as R-13, whereas modern building codes typically require insulation between R-38 and R-60.
The new federal tax credit offers up to 30% of the total cost of a project for air sealing and insulation, maxing out at $1,200 total. (Labor costs are not covered by the credit.)
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Having a light-colored roof and exterior will most certainly keep your home cooler than darker options, but not all light colors are created equal. “Cool” roofs and walls are made with special materials that reflect solar energy back into space, preventing it from being absorbed by the building. They also have high “thermal emittance,” meaning they release a lot of the heat that they do absorb, rather than sending it indoors.
All kinds of materials have been developed with these properties. For roofs, there are tiles, shingles, membranes, liquid coatings, and products made of slate, wood, and metal.
Cool roofs don’t necessarily have to be white, although the color does work very well. According to a database maintained by the Cool Roof Ratings Council, the most effective products tend to be bright white coatings, but there are also gray, green, blue, brown, and tan products that are rated highly.
For reflective walls, the most effective products similarly come in white and other light-colored paints, which can reflect 60 to 90 percent of sunlight when new. An extensive 2019 study of reflective wall paints by the same group at Lawrence Berkeley National Lab found that cool walls can reduce annual energy use in single-family homes in warmer U.S. climates by 2% to 8.5%.
Easley said it’s worth considering a cool roof if you have a central air conditioning system in your attic. Otherwise, attics in places like Arizona can get upwards of 130 degrees, taxing the equipment and forcing it to work harder. If your attic isn’t home to your AC, it may only make financial sense to do this kind of retrofit if your house is already in need of a new paint job or your roof needs work.
But it’s probably not worth considering a cool roof if you live in a colder climate, like the Northeast and upper Midwest, since cool roofs can actually make it colder inside in the winter.
There’s no federal incentives for cool roofs, but several states and utilities offer rebates.
This is a big category, and it’s easy to get overwhelmed by the options. Starting with those that will likely cost the most to the least, you can:
• Replace your windows altogether.
• Add storm windows to the interior or exterior of your existing glass.
• Purchase films that can be applied to the existing glass to increase its reflectivity.
• Install external shutters or awnings that block the sun.
• Install interior blinds and curtains that block the sun.
Here’s a rundown of each option.
New windows: Replacing your windows can cost tens of thousands of dollars, so unless they are already in need of repair, you may want to hold off on that option. But when the day does come around, you’ll want to look for “Low-E” windows, which stands for low emissivity. The inside of the glass is coated with microscopic layers of silver that reflect heat while still allowing light to pass through.
Within that category, you’ll also want to look for windows that have what’s called a low “solar heat gain coefficient.” This measures how much heat is absorbed by the glass and transferred inside. It’s rated on a scale of 0 to 1. If you live somewhere that’s sunny year round like Arizona, you ideally want one rated 0.25 or lower.
Through 2032, homeowners can claim up to $600 in federal tax credits for purchasing Energy Star rated windows.
Storm windows: Rather than replacing your windows entirely, it’s far cheaper to install storm windows with Low-E glass, which basically involves bolting another window to the outside of your house. Storm windows have an added benefit of improving air sealing, eliminating drafts.
Film: An even lower-cost option is to look into films with low solar heat gain coefficients that can be applied to existing windows. However, Easeley warned that many manufacturers will void your warranty if you add films to your windows.
Shutters, awnings, blinds, and curtains: Exterior shutters and overhangs that block the sun from ever reaching your windows will generally be more effective than interior shades or blinds, but all of these measures can help. “Window blinds and curtains are really dirt cheap ways to control energy,” said Maurer. “It’s not a very good buffer, but it’s something.”
The Berkeley study on passive cooling measures notes that blinds moderately improve how much heat from the sun enters your home, but they can feel more effective by reducing the sensation of sunlight streaming into your house.
If you still have any incandescent lights, they can also be a significant source of heat. They should be replaced with LED lights.
Planting trees, climbing ivy, and other vegetation can also passively cool your house by shading both your house and any surrounding pavement. However, if you have solar panels, or plan to get them in the future, do not plant trees on the south side of your home as it may reduce the solar system’s effectiveness.
Maurer cautioned that if you do a bunch of work in your home to reduce your cooling needs, you’ll want to keep that in mind if you ever have to replace your air conditioner. He advised having a contractor come in to re-measure what size system you need, since doing a like-for-like replacement will probably be overkill and could result in it malfunctioning.
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It’s already conquered solar, batteries, and EVs. With a $2 billion new turbine factory in Scotland, it may have set its next target.
Batteries, solar panels, electric vehicles. The story of renewable energy deployment globally is increasingly one of China’s fiercely competitive domestic industries and deep supply chains exporting their immense capacity globally. Now, it may be wind’s turn.
The Chinese turbine manufacturer Ming Yang announced last week that it plans to invest $2 billion in a factory in Scotland. The facility is scheduled to start production in late 2028, churning out offshore wind equipment for use in the United Kingdom, which has over 15 gigawatts of offshore wind capacity, as well as for export, likely in Europe.
The deal comes as China finds itself at a kind of domestic clean energy crossroads, in terms of both supply and demand. On the former, the country has launched a campaign aimed at softening the cutthroat domestic competition, overproduction, and price wars that have defined many of its green industries, especially electric vehicles.
At the same time, China is setting out to alter its electricity markets to put renewable energy on a more market-based footing, while also paying coal-fired power plants to stay on the grid, as University of California, San Diego researcher Michael Davidson explained on a recent episode of Shift Key. These changes in electricity markets will reduce payments to solar and wind producers, making foreign markets potentially more attractive.
“We anticipate Chinese original equipment manufacturers will intensify their push toward international expansion, with Mingyang’s planned investment a signal of this trend,” Morningstar analyst Tancrede Fulop wrote in a note to clients. “This poses a challenge for Western incumbents, as Chinese players can capitalize on their cost advantages in a market driven by price.”
Ironically, Fulop said, the market changes will make the Chinese market more like Europe’s, which has become more price conscious as the market has matured and reductions in cost have slowed or outright stopped. “The transition is expected to make renewable developers increasingly price-sensitive as they seek to preserve project returns, ultimately weighing on wind turbine manufacturers’ profitability,” he wrote.
There’s a “cliff” coming in Chinese renewable energy deployment, Kyle Chan, a postdoctoral researcher at Princeton University, told me. “Overall, the net effect is expected to be a pretty sharp drop, and we’re already starting to see some of the effects of that.”
And turbine manufacturers would not be the first Chinese renewable industry to show up in Europe.
“There’s already an existing model” for Chinese manufacturers to set up shop in Western countries, Chan said. Chinese companies are already planning to manufacture solar modules in France, while Chinese EV maker BYD’s is planning factories in Hungary, Turkey, and potentially Spain.
China as a whole is responsible for over half of all new offshore wind capacity added in 2024, according to Global Energy Monitor, and has been growing at a 41% annual rate for the past five years. The energy intelligence firm Rystad estimates that China will make up 45% of all offshore wind capacity by 2030. Ming Yang itself claims to be behind almost a third of new offshore wind capacity built last year.
Meanwhile, offshore wind projects in the West — especially the United States — have faced the omnicrisis of high interest rates, backed-up supply chains, and Donald Trump. News of Ming Yang’s Scotland factory sent yet another shock through the ailing Western offshore wind market, with shares in the Danish company Vestas down 4% when the market opened Monday.
But with Chinese products and Chinese investment comes controversy and nerves among European political leaders. “There’re questions about tech transfer and job creation,” Chan said. “They also face some security issues and potential political backlash.”
In August, the German asset manager Luxcara announced that it would use Siemens Gamesa turbines for a planned offshore wind project instead of Ming Yang ones after backlash from German defense officials. “We see this as further evidence that a Chinese entry into the European wind market remains challenging,” analysts at Jefferies wrote to clients in August.
They were right to be skeptical — Chinese turbines’ entry into the European market has been long predicted and yet remains unrealized. “China’s increasingly cheap wind turbines could open new markets,” S&P Global Insights wrote in 2022, citing the same cost advantages as Morningstar did in reference to the Ming Yang factory announcement.
“China was already trying to angle into the European market,” Chan told me, seeing it as comparable to the U.S. in size and potentially more open to Chinese investment. “If they were kind of thinking about it before, now it’s gotten a greater sense of commercial urgency because I think the expectation is that their profit margins are really going to get squeezed.”
While China leads the world in building out renewable energy capacity domestically and exporting technology abroad, it has “decided not to decide” on pursuing a rapid, near-term decarbonization, Johns Hopkins University China scholar Jeremy Wallace recently argued in Heatmap.
While that means that the Paris Agreement goals are even farther out of reach, it may be fine for Chinese industries, including wind, as they look to sell abroad.
“Chinese firms have lots of reasons to want to build things abroad: Diversification away from the Chinese market, the zero or negative profits from selling domestically, and geopolitical balancing,” Wallace told me.
“If Brits want to have their citizens making the turbines that will power the country,” Wallace said, “this seems like a reasonable opportunity.”
Current conditions: A major Pacific storm is drenching California and bringing several inches of snow to Montana, Idaho, and Wyoming • A tropical storm in the Atlantic dumped nearly a foot of water on South Carolina over three days • Algeria is roasting in temperatures of more than 105 degrees Fahrenheit.
The Department of Energy notified workers in multiple offices Friday that they were likely to be fired or reassigned to another part of the agency, E&E News reported Tuesday. Staffers at the Office of Clean Energy Demonstrations and the Office of State and Community Energy Programs received notices stating that the offices would “be undergoing a major reorganization and your position may be reassigned to another organization, transferred to another function or abolished.” Still, the notice said “no determination has been made concerning your specific position” just yet.
At least five offices received “general reduction in force notices,” as opposed to official notification of a reduction in force, according to a Latitude Media report. These included the Office of Clean Energy Demonstrations, the Office of Energy Efficiency and Renewable Energy, the Office of State and Community Energy Plans, and the Office of Fossil Energy. Nearly 200 Energy Department employees received direct layoff notices.
Catastrophic floods brought on by the remnants of a typhoon devastated the Alaska Native village of Kipnuk on Sunday. Five months ago, the Trump administration canceled a $20 million grant intended to protect the community against exactly this kind of extreme flooding, The New York Times reported Tuesday. The grant from the Environmental Protection Agency was meant to stabilize the riverbank on which Kipnuk is built. But in May, the agency yanked back the Biden-era grant, which EPA Administrator Lee Zeldin said was “no longer consistent” with the government’s priorities. In a post on X, Zeldin said the award was part of "wasteful DEI and Environmental Justice grants,” suggesting the funding was part of an ideological push for diversity, equity, and inclusion rather than a practical infrastructure boost to an Indigenous community facing serious challenges.
Zealan Hoover, a Biden-era senior adviser at the EPA, accused Zeldin of using “inflammatory rhetoric” that misrepresented the efforts in places like Kipnuk. “For decades, E.P.A. has been a partner to local communities,” Hoover said. “For the first time under this administration, E.P.A. has taken an aggressively adversarial posture toward the very people and communities that it is intended to protect.”
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Late last Thursday, Heatmap’s Jael Holzman observed that the status of the 6.2-gigawatt Esmeralda 7, the nation’s largest solar project, had changed on the Bureau of Land Management’s website to “canceled.” The news sent shockwaves nationwide and drew blowback even from Republicans, including Utah Governor Spencer Cox, as I reported in this newsletter. Now, however, the bureau’s parent agency is denying that it made the call to cancel the project. “During routine discussions prior to the lapse in appropriations, the proponents and BLM agreed to change their approach for the Esmeralda 7 Solar Project in Nevada,” a spokesperson for the Department of the Interior told Utility Dive. “Instead of pursuing a programmatic level environmental analysis, the applicants will now have the option to submit individual project proposals to the BLM to more effectively analyze potential impacts.”
That means the project could still move forward with a piecemeal approach to permitting rather than one overarching approval, which aligns with what one of the developers involved told Jael last week. A representative for NextEra said that it is “in the early stage of development” with its portion of the Esmeralda 7 mega-project, and that the company is “committed to pursuing our project’s comprehensive environmental analysis by working closely with the Bureau of Land Management.” Still, the move represents a devastating setback for the solar installation, which may never fully materialize.
Ethane exports are rising as export capacity soars.EIA
U.S. exports of ethane, a key petrochemical feedstock extracted from raw natural gas during processing, are on track for “significant growth” through 2026, according to new analysis from the Energy Information Administration. Overseas sales are projected to grow 14% this year compared to the previous year, and another 16% next year. Ethane is mostly used as a feedstock for ethylene, a key ingredient in plastics, resins, and synthetic rubber. China has been the fastest growing source of demand for American ethane in recent years, rising to the largest single destination with 47% of exports last year.
Spain’s electricity-grid operator shrugged off concerns of another major blackout after detecting two sharp voltage variations in recent weeks. Red Electrica, which operates Spain’s grid, said that what The Wall Street Journal described as “recent voltage swings” didn’t threaten to knock out the grid because they stayed within acceptable limits. But the operator warned that variations could jeopardize the electricity supply if the grid didn’t overhaul its approach to managing a system that increasingly relies on intermittent, inverter-based generating sources such as solar panels. Red, which is 20% owned by the Spanish government, acknowledged that the high penetration of renewables was responsible for the recent fluctuations. Among the changes needed to improve the grid: real-time monitoring, which Heatmap’s Matthew Zeitlin noted in April “is necessary because traditionally, grid inertia is just thought of as an inherent quality of the system, not something that has to be actively ensured and bolstered.”
It’s not just Spain facing blackouts. New York City will have a power deficiency equivalent to the energy needed to power between 410,000 and 650,000 homes next summer — and that number could double by 2050, the state’s grid operator warned this week in its latest five-year report. “The grid is at a significant inflection point,” Zach Smith, senior vice president of system and resource planning for NYISO, said in a statement to Gothamist. “Depending on future demand growth and generator retirements, the system may need several thousand megawatts of new dispatchable generation within the next 10 years.”
Sodium-ion batteries are all the rage, as Heatmap’s Katie Brigham reported yesterday about the commercial breakthrough by the startup Alsym. But a major challenge facing sodium-ion batteries compared to lithium-ion rivals is the stability of the cathode material in air and water, which can degrade the battery’s performance and lifespan. A new study by researchers at Tokyo University of Science found that one ingredient can solve the problem: Calcium. By discovering the protective effects of calcium doping in the batteries, “this study could pave the way for the widespread adoption” of sodium-ion batteries.
Rob talks with the author and activist about his new book, We Survived the Night.
Julian Brave NoiseCat is a writer, Oscar-nominated filmmaker, champion powwow dancer, and student of Salish art and history. His first book, We Survived the Night, was released this week — it uses memoir, reporting, and literary anthology to tell the story of Native families across North America, including his own.
NoiseCat was previously an environmental and climate activist at groups including 350.org and Data for Progress. On this week’s episode of Shift Key, Rob talks with Julian about Native American nations and politics, the complexity and reality of Native life in 2025, and the “trickster” as a recurring political archetype.
Shift Key is hosted by Robinson Meyer, the founding executive editor of Heatmap, and Jesse Jenkins, a professor of energy systems engineering at Princeton University. Jesse is off this week.
Subscribe to “Shift Key” and find this episode on Apple Podcasts, Spotify, Amazon, YouTube, or wherever you get your podcasts.
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Here is an excerpt from our conversation:
Robinson Meyer: What were lessons that you took away from the writing of the book, or from the reporting of the book, that changed how you thought about climate or the environment in some way that maybe wasn’t the case when you were working on these issues full time?
Julian Brave NoiseCat: I would say that while I was working on climate issues, I was actually, myself, really changing a lot in terms of my thoughts on how politics worked and did not work. I think I came into my period of my life as a climate activist really believing in the power of direct action, and protest, and, you know, if you get enough people in the streets and you get enough politicians on your side, you eventually can change the laws. And I think that there is some truth to that view.
But I think being in DC for four years, being really involved in this movement, conversation — however you want to put that — around the Green New Deal, around eventually a Biden administration and how that would be shaped around how they might go about actually taking on climate change for the first time in U.S. history in a significant way, really transformed my understanding of how change happens. I got a greater appreciation, for example, for the importance of persuading people to your view, particularly elites in decision-making positions. And I also started to understand a little bit more of the true gamesmanship of politics — that there is a bit of tricks and trickery, and all kinds of other things that are going on in our political system that are really fundamental to how it all works.
And I bring that last piece up because while I was writing the book, I was also thinking really purposefully about my own people’s narrative traditions, and how they get at transformations and how they happen in the world. And it just so happens that probably the most significant oral historical tradition of my own people is a story called a coyote story, which is about a trickster figure who makes change in the world through cunning and subterfuge and tricks, and also who gets tricked himself a fair amount.
And I think that in that worldview, I actually found a lot of resonance with my own observations on how political change happened when I was in Washington, D.C., and so that insight did really deeply shape the book.
Mentioned:
We Survived the Night, by Julian Brave NoiseCat
How Deb Haaland Became the First Native American Cabinet Secretary
This episode of Shift Key is sponsored by …
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A warmer world is here. Now what? Listen to Shocked, from the University of Chicago’s Institute for Climate and Sustainable Growth, and hear journalist Amy Harder and economist Michael Greenstone share new ways of thinking about climate change and cutting-edge solutions. Find it here.
Music for Shift Key is by Adam Kromelow.