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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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The Department of Energy has put together a list of sites and is requesting proposals from developers, Heatmap has learned.
The Department of Energy is moving ahead with plans to allow companies to build AI data centers and new power plants on federal land — and it has put together a list of more than a dozen sites nationwide that could receive the industrial-scale facilities, according to an internal memo obtained by Heatmap News.
The memo lists sites in Texas, Illinois, New Jersey, Colorado, and other locations. The government could even allow new power plants — including nuclear reactors and carbon-capture operations — to be built on the same sites to generate enough electricity to power the data centers, the memo says.
Trump officials hope to start construction on the new data centers by the end of this year and switch them on by the end of 2027, according to the memo.
The agency will request formal feedback from artificial intelligence companies and developers about how best to proceed with its proposal as soon as Thursday, according to an individual who wasn’t authorized to speak about the matter publicly.
The effort, aimed at maintaining America’s “global AI dominance,” represents one of the few points of agreement between the Trump and Biden administrations. In the final days of his term, President Biden ordered the government to identify federal properties where new data centers could be built.
Scarcely a week later, President Trump issued an executive order lifting all Biden-era limits on AI development — but keeping the mandate to move quickly to maintain America’s alleged edge in the new technology. “It is the policy of the United States to sustain and enhance America’s global AI dominance,” the Trump order said.
The new memo proposes a list of 16 federal sites that could host AI data centers, new power plants, and other “AI infrastructure.” They include several sites where nuclear weapon components are made, including the Pantex site near Amarillo, Texas, and the Kansas City National Security Campus, which is operated by Honeywell International. The other candidate sites are:
Other sites could still be considered, the memo says, and the current list has no particular ranking or order.
The offer may not be enough to convince developers to work with the federal government, one energy expert told me.
“I think it’s important that the government is thinking about how to help the industry, but you also have to think about it from the perspective of the industry a little bit. Why is doing this on a DOE site better than doing this as a project in Texas?” said Peter Freed, a founding partner at the Near Horizon Group and the former director of energy strategy at Meta.
“Historically, the perspective is that anything involving government land just adds complexity,” Freed told me. “I love Idaho National Lab. It’s a national treasure. But if you want a data center there by the end of 2027 — where is the power going to come from?”
Only if the government were able to guarantee fast-track access to certain kinds of equipment — such as transformers or circuit breakers, which are in a severe shortage — would it make sense for most developers to work with them, he said.
The new memo raises the idea that “innovative energy technologies” including “nuclear reactors, enhanced geothermal systems, fuel cells, carbon capture, energy storage systems, and portfolios of on-site technologies” could be considered to power the new data centers.
The memo asks potential developers, “What information would you need to determine the suitability of various energy storage systems (e.g., subsurface thermal energy storage, flow battery, metal anode battery) as a means for supporting data center cooling or other operations?” It also asks what companies would need to know about a site’s suitability for carbon capture and storage operations. It asks, too, what information might be needed about a site’s topography, physical security, and earthquake risk to build a new nuclear power plant.
The memo doesn’t mention wind turbines or new solar farms, although they could fall under some of the terms it sets out. It also asks companies what information they might need about nearby nuclear power plants or the local power grid — and it inquires whether some data center operations could be turned on and off depending on local power availability.
Although the government could allow new data centers to be built, it won’t accept all liability for them. The memo adds that companies might need to “agree to bear all responsibility for costs and liabilities related to construction and operation of the Al data centers as well as other infrastructure upgrades necessary to support those data centers.”
The Trump administration seems intent on moving quickly on the proposal. Once it publishes the request, companies will have 30 days to respond.
Current conditions: A rare wildfire alert has been issued for London this week due to strong winds and unseasonably high temperatures • Schools are closed on the Greek islands of Mykonos and Paros after a storm caused intense flooding • Nearly 50 million people in the central U.S. are at risk of tornadoes, hail, and historic levels of rain today as a severe weather system barrels across the country.
President Trump today will outline sweeping new tariffs on foreign imports during a “Liberation Day” speech in the White House Rose Garden scheduled for 4 p.m. EST. Details on the levies remain scarce. Trump has floated the idea that they will be “reciprocal” against countries that impose fees on U.S. goods, though the predominant rumor is that he could impose an across-the-board 20% tariff. The tariffs will be in addition to those already announced on Chinese goods, steel and aluminum, energy imports from Canada, and a 25% fee on imported vehicles, the latter of which comes into effect Thursday. “The tariffs are expected to disrupt the global trade in clean technologies, from electric cars to the materials used to build wind turbines,” explained Josh Gabbatiss at Carbon Brief. “And as clean technology becomes more expensive to manufacture in the U.S., other nations – particularly China – are likely to step up to fill in any gaps.” The trade turbulence will also disrupt the U.S. natural gas market, with domestic supply expected to tighten, and utility prices to rise. This could “accelerate the uptake of coal instead of gas, and result in a swell in U.S. power emissions that could accelerate climate change,” Reutersreported.
Republican candidates won in two House races in Florida on Tuesday, one of which was looking surprisingly tight going into the special elections. The victories by Jimmy Patronis in Florida’s First District and Randy Fine in the Sixth District bolster the party’s slim House majority and could spell trouble for the Inflation Reduction Act as the House Ways and Means Committee mulls which programs to cut to pay for tax cuts. But the result in Wisconsin’s Supreme Court election was less rosy for Republicans. Liberal Judge Susan Crawford defeated conservative Brad Schimel despite Schimel’s huge financial backing from Tesla CEO and Trump adviser Elon Musk, who poured some $15 million into the competition. The outcome “could tarnish the billionaire’s political clout and trigger worry for some Republicans about how voters are processing the opening months of Trump’s new administration,” as The Wall Street Journalexplained.
The Trump administration announced mass layoffs across the Department of Health and Human Services on Wednesday, part of a larger effort to reduce the agency’s workforce by 25%. The cuts included key staffers with the Low Income Home Energy Assistance Program, which has existed since 1981 and helps some 6.7 million low-income households pay their energy bills. A 2022 white paper calls LIHEAP “one of the most critical components of the social safety net.” The move comes at a time when many U.S. utilities are preparing to raise their energy prices to account for higher costs for materials, labor, and grid upgrades. In a scathing letter to HHS Secretary Robert F. Kennedy. Jr., Senate Energy and Commerce Democrats call the workforce cuts “reckless” and demand detailed explanations for why roles have been eliminated.
Energy storage startup Energy Vault on Wednesday announced it had closed $28 million in project financing for a hybrid green hydrogen microgrid energy storage facility in California. The firm says its Calistoga Resiliency Center, deployed in partnership with utility company Pacific Gas & Electric, is “specifically designed to address power resiliency given the growing challenges of wildfire risk in California.” The zero-emission system will feature advanced hydrogen fuel cells that are integrated with lithium-ion batteries, which can provide about 48 hours of back-up power via a microgrid to the city of Calistoga during wildfire-related power shutoffs. The site is expected to be commercially operational in the second quarter of 2025.
“The CRC serves as a model for Energy Vault’s future utility-scale hybrid microgrid storage system deployments as the only existing zero-emission solution to address [power shutoff] events that is scalable and ready to be deployed across California and other regions prone to wildfires,” the company said in a press release. As Heatmap’s Katie Brigham wrote last fall, PG&E has become an important partner for climate and energy tech companies with the potential to reduce risk and improve service on the grid.
China will finalize its first-ever sale of a green sovereign bond Wednesday. The country is expected to issue the bond on the London Stock Exchange and has reportedly received more than $5 billion in bids. “It’s no coincidence that China has chosen to list its debut green bond in London, given European investors’ continued strong demand for environmental products,” Bloombergnoted. Green bonds are investment vehicles that raise money exclusively for projects that benefit the climate or environment. China’s finance ministry wants the bond to “attract international funds to support domestic green and low-carbon development,” and specifically climate change mitigation and adaptation, nature conservation and biodiversity, and pollution prevention and control. Some of the money raised might also go toward China’s EV charging infrastructure, according toReuters.
GE Vernova has now produced more than half of the turbines needed for the SunZia Wind project in New Mexico. When completed in 2026, the 2.4 gigawatt project will be the largest onshore wind farm in the Western Hemisphere.
Rob and Jesse catch up on the Greenhouse Gas Reduction Fund with former White House official Kristina Costa.
The Inflation Reduction Act dedicated $27 billion to build a new kind of climate institution in America — a network of national green banks that could lend money to companies, states, schools, churches, and housing developers to build more clean energy and deploy more next-generation energy technology around the country.
It was an innovative and untested program. And the Trump administration is desperately trying to block it. Since February, Trump’s criminal justice appointees — led by Ed Martin, the interim U.S. attorney for the District of Columbia — have tried to use criminal law to undo the program. After failing to get the FBI and Justice Department to block the flow of funds, Trump officials have successfully gotten the program’s bank partner to freeze relevant money. The new green banks have sued to gain access to the money.
On this week’s episode of Shift Key, Rob and Jesse talk with Kristina Costa, who has been tracking the effort to bankrupt the green banks. Costa helped lead the Inflation Reduction Act’s implementation in the White House from 2022 to 2025 — and is a previous Shift Key guest. She joins us to discuss how Trump is weaponing criminal law to block a climate program, whether there’s any precedent for his actions, and what could come next in the legal battle. 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.
Subscribe to “Shift Key” and find this episode on Apple Podcasts, Spotify, Amazon, or wherever you get your podcasts.
You can also add the show’s RSS feed to your podcast app to follow us directly.
Here is an excerpt from our conversation:
Robinson Meyer: There's kind of two lines you hear from the Trump administration about this, two claims made by the Trump administration about the reason for these seizures, and I just wanna talk about them briefly because this is an unprecedented action. We should look at why the government has claimed that it needs to take this unprecedented action.
The first has to do with this video made by Project Veritas, a kind of conservative media organization …
Kristina Costa: A hit squad.
Meyer: A hit squad that recorded, unwittingly, an EPA official who described the EPA’s actions during December 2024, between the loss of the election and the inauguration, as “throwing gold bars off the Titanic.” That the agency was so eager and desperate to spend as much of the IRA down as it could before the Trump administration took office that it was like they were throwing gold bars off the Titanic — you know, a sinking ship.
The EPA administrator has fixated on this line and described it as waste and self-dealing, suggesting reckless financial mismanagement, blatant conflicts of interest, astonishing sums of tax dollars awarded to unqualified recipients and severe deficiencies of regulatory oversight.
You were involved in setting up the IRA. I wonder, first of all, just how do you reflect on this episode? And second of all, was the Biden administration doing the proverbial version of throwing gold bars off the Titanic during the post-election period?
Costa: Yeah, so I mean, it falls apart as any sort of quote-unquote evidence in what's happening with the Greenhouse Gas Reduction Fund if you just believe in the linear nature of time. So, as I said, we announced EPA made the selections in April of 2024. The funds were fully obligated in August of 2024. Grantees were starting to make announcements about investments in October of 2024 — all dates which precede election day by weeks to months. And so it is just a complete fabrication on the part of Lee Zeldin that there was any sort of inappropriate action on the part of the Biden EPA or any of the other agencies in doing what Congress directed us to do, which was to award and obligate funds to recipients consistent with the provisions of the Inflation Reduction Act that authorized and appropriated funds for the programs.
We had also — and I think I might have said this when I was with you guys in December — one of the first things that we did, from the White House implementation team, was to meet with all of our grant agencies and, in September and October of 2022, set targets for them for how much funding we wanted them to try to award and obligate by the end of the administration. And we set a goal, basically, that we would be aiming to have at least 80% of the available funds obligated by the end of 2024. And we hit that. And so the idea that there was some massive acceleration post-election — like, were there some contracts that the agencies obligated in December and January that, in the event of a Kamala Harris administration, they would've maybe obligated in February and March instead? Sure. I'm not going to say otherwise, but those grants had been made already. There wasn't this rush of actual decision-making.
Music for Shift Key is by Adam Kromelow.