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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.
Read another helpful guide about heat:
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Instead of rocket fuel, they’re burning biomass.
Arbor Energy might have the flashiest origin story in cleantech.
After the company’s CEO, Brad Hartwig, left SpaceX in 2018, he attempted to craft the ideal resume for a future astronaut, his dream career. He joined the California Air National Guard, worked as a test pilot at the now-defunct electric aviation startup Kitty Hawk, and participated in volunteer search and rescue missions in the Bay Area, which gave him a front row seat to the devastating effects of wildfires in Northern California.
That experience changed everything. “I decided I actually really like planet Earth,” Hartwig told me, “and I wanted to focus my career instead on preserving it, rather than trying to leave it.” So he rallied a bunch of his former rocket engineer colleagues to repurpose technology they pioneered at SpaceX to build a biomass-fueled, carbon negative power source that’s supposedly about ten times smaller, twice as efficient, and eventually, one-third the cost of the industry standard for this type of plant.
Take that, all you founders humble-bragging about starting in a dingy garage.
“It’s not new science, per se,” Hartwig told me. The goal of this type of tech, called bioenergy with carbon capture and storage, is to combine biomass-based energy generation with carbon dioxide removal to achieve net negative emissions. Sounds like a dream, but actually producing power or heat from this process has so far proven too expensive to really make sense. There are only a few so-called BECCS facilities operating in the U.S. today, and they’re all just ethanol fuel refineries with carbon capture and storage technology tacked on.
But the advances in 3D printing and computer modeling that allowed the SpaceX team to build an increasingly simple and cheap rocket engine have allowed Arbor to move quickly into this new market, Hartwig explained. “A lot of the technology that we had really pioneered over the last decade — in reactor design, combustion devices, turbo machinery, all for rocket propulsion — all that technology has really quite immediate application in this space of biomass conversion and power generation.”
Arbor’s method is poised to be a whole lot sleeker and cheaper than the BECCS plants of today, enabling both more carbon sequestration and actual electricity production, all by utilizing what Hartwig fondly refers to as a “vegetarian rocket engine.” Because there’s no air in space, astronauts have to bring pure oxygen onboard, which the rocket engines use to burn fuel and propel themselves into the stratosphere and beyond. Arbor simply subs out the rocket fuel for biomass. When that biomass is combusted with pure oxygen, the resulting exhaust consists of just CO2 and water. As the exhaust cools, the water condenses out, and what’s left is a stream of pure carbon dioxide that’s ready to be injected deep underground for permanent storage. All of the energy required to operate Arbor’s system is generated by the biomass combustion itself.
“Arbor is the first to bring forward a technology that can provide clean baseload energy in a very compact form,” Clea Kolster, a partner and Head of Science at Lowercarbon Capital told me. Lowercarbon is an investor in Arbor, alongside other climate tech-focused venture capital firms including Gigascale Capital and Voyager Ventures, but the company has not yet disclosed how much it’s raised.
Last month, Arbor signed a deal with Microsoft to deliver 25,000 tons of permanent carbon dioxide removal to the tech giant starting in 2027, when the startup’s first commercial project is expected to come online. As a part of the deal, Arbor will also generate 5 megawatts of clean electricity per year, enough to power about 4,000 U.S. homes. And just a few days ago, the Department of Energy announced that Arbor is one of 11 projects to receive a combined total of $58.5 million to help develop the domestic carbon removal industry.
Arbor’s current plan is to source biomass from forestry waste, much of which is generated by forest thinning operations intended to prevent destructive wildfires. Hartwig told me that for every ton of organic waste, Arbor can produce about one megawatt hour of electricity, which is in line with current efficiency standards, plus about 1.8 tons of carbon removal. “We look at being as efficient, if not a little more efficient than a traditional bioenergy power plant that does not have carbon capture on it,” he explained.
The company’s carbon removal price targets are also extremely competitive — in the $50 to $100 per ton range, Hartwig said. Compare that to something like direct air capture, which today exceeds $600 per ton, or enhanced rock weathering, which is usually upwards of $300 per ton. “The power and carbon removal they can offer comes at prices that meet nearly unlimited demand,”Mike Schroepfer, the founder of Gigascale Capital and former CTO of Meta, told me via email. Arbor benefits from the fact that the electricity it produces and sells can help offset the cost of the carbon removal, and vice versa. So if the company succeeds in hitting its cost and efficiency targets, Hartwig said, this “quickly becomes a case for, why wouldn’t you just deploy these everywhere?”
Initial customers will likely be (no surprise here) the Microsofts, Googles and Metas of the world — hyperscalers with growing data center needs and ambitious emissions targets. “What Arbor unlocks is basically the ability for hyperscalers to stop needing to sacrifice their net zero goals for AI,” Kolster told me. And instead of languishing in the interminable grid interconnection queue, Hartwig said that providing power directly to customers could ensure rapid, early deployment. “We see it as being quicker to power behind-the-meter applications, because you don’t have to go through the process of connecting to the grid,” he told me. Long-term though, he said grid connection will be vital, since Arbor can provide baseload power whereas intermittent renewables cannot.
All of this could serve as a much cheaper alternative, to say, re-opening shuttered nuclear facilities, as Microsoft also recently committed to doing at Three Mile Island. “It’s great, we should be doing that,” Kolster said of this nuclear deal, “but there’s actually a limited pool of options to do that, and unfortunately, there is still community pushback.”
Currently, Arbor is working to build out its pilot plant in San Bernardino, California, which Hartwig told me will turn on this December. And by 2030, the company plans to have its first commercial plant operating at scale, generating 100 megawatts of electricity while removing nearly 2 megatons of CO2 every year. “To put it in perspective: In 2023, the U.S. added roughly 9 gigawatts of gas power to the grid, which generates 18 to 23 megatons of CO2 a year,” Schroepfer wrote to me. So having just one Arbor facility removing 2 megatons would make a real dent. The first plant will be located in Louisiana, where Arbor will also be working with an as-yet-unnamed partner to do the carbon storage.
The company’s carbon credits will be verified with the credit certification platform Isometric, which is also backed by Lowercarbon and thought to have the most stringent standards in the industry. Hartwig told me that Arbor worked hand-in-hand with Isometric to develop the protocol for “biogenic carbon capture and storage,” as the company is the first Isometric-approved supplier to use this standard.
But Hartwig also said that government support hasn’t yet caught up to the tech’s potential. While the Inflation Reduction Act provides direct air capture companies with $180 per ton of carbon dioxide removed, technology such as Arbor’s only qualifies for $85 per ton. It’s not nothing — more than the zero dollars enhanced rock weathering companies such as Lithos or bio-oil sequestration companies such as Charm are getting. “But at the same time, we’re treated the same as if we’re sequestering CO2 emissions from a natural gas plant or a coal plant,” Hartwig told me, as opposed to getting paid for actual CO2 removal.
“I think we are definitely going to need government procurement or involvement to actually hit one, five, 10 gigatons per year of carbon removal,” Hartwig said. Globally, scientists estimate that we’ll need up to 10 gigatons of annual CO2 removal by 2050 in order to limit global warming to 1.5 degrees Celsius. “Even at $100 per ton, 10 gigatons of carbon removal is still a pretty hefty price tag,” Hartwig told me. A $1 trillion price tag, to be exact. “We definitely need more players than just Microsoft.”
New research out today shows a 10-fold increase in smoke mortality related to climate change from the 1960s to the 2010.
If you are one of the more than 2 billion people on Earth who have inhaled wildfire smoke, then you know firsthand that it is nasty stuff. It makes your eyes sting and your throat sore and raw; breathe in smoke for long enough, and you might get a headache or start to wheeze. Maybe you’ll have an asthma attack and end up in the emergency room. Or maybe, in the days or weeks afterward, you’ll suffer from a stroke or heart attack that you wouldn’t have had otherwise.
Researchers are increasingly convinced that the tiny, inhalable particulate matter in wildfire smoke, known as PM2.5, contributes to thousands of excess deaths annually in the United States alone. But is it fair to link those deaths directly to climate change?
A new study published Monday in Nature Climate Change suggests that for a growing number of cases, the answer should be yes. Chae Yeon Park, a climate risk modeling researcher at Japan’s National Institute for Environmental Studies, looked with her colleagues at three fire-vegetation models to understand how hazardous emissions changed from 1960 to 2019, compared to a hypothetical control model that excluded historical climate change data. They found that while fewer than 669 deaths in the 1960s could be attributed to climate change globally, that number ballooned to 12,566 in the 2010s — roughly a 20-fold increase. The proportion of all global PM2.5 deaths attributable to climate change jumped 10-fold over the same period, from 1.2% in the 1960s to 12.8% in the 2010s.
“It’s a timely and meaningful study that informs the public and the government about the dangers of wildfire smoke and how climate change is contributing to that,” Yiqun Ma, who researches the intersection of climate change, air pollution, and human health at the Yale School of Medicine, and who was not involved in the Nature study, told me.
The study found the highest climate change-attributable fire mortality values in South America, Australia, and Europe, where increases in heat and decreases in humidity were also the greatest. In the southern hemisphere of South America, for example, the authors wrote that fire mortalities attributable to climate change increased from a model average of 35% to 71% between the 1960s and 2010s, “coinciding with decreased relative humidity,” which dries out fire fuels. For the same reason, an increase in relative humidity lowered fire mortality in other regions, such as South Asia. North America exhibited a less dramatic leap in climate-related smoke mortalities, with climate change’s contribution around 3.6% in the 1960s, “with a notable rise in the 2010s” to 18.8%, Park told me in an email.
While that’s alarming all on its own, Ma told me there was a possibility that Park’s findings might actually be too conservative. “They assume PM2.5 from wildfire sources and from other sources” — like from cars or power plants — “have the same toxicity,” she explained. “But in fact, in recent studies, people have found PM2.5 from fire sources can be more toxic than those from an urban background.” Another reason Ma suspected the study’s numbers might be an underestimate was because the researchers focused on only six diseases that have known links to PM2.5 exposure: chronic obstructive pulmonary disease, lung cancer, coronary heart disease, type 2 diabetes, stroke, and lower respiratory infection. “According to our previous findings [at the Yale School of Medicine], other diseases can also be influenced by wildfire smoke, such as mental disorders, depression, and anxiety, and they did not consider that part,” she told me.
Minghao Qiu, an assistant professor at Stony Brook University and one of the country’s leading researchers on wildfire smoke exposure and climate change, generally agreed with Park’s findings, but cautioned that there is “a lot of uncertainty in the underlying numbers” in part because, intrinsically, wildfire smoke exposure is such a complicated thing to try to put firm numbers to. “It’s so difficult to model how climate influences wildfire because wildfire is such an idiosyncratic process and it’s so random, ” he told me, adding, “In general, models are not great in terms of capturing wildfire.”
Despite their few reservations, both Qiu and Ma emphasized the importance of studies like Park’s. “There are no really good solutions” to reduce wildfire PM2.5 exposure. You can’t just “put a filter on a stack” as you (sort of) can with power plant emissions, Qiu pointed out.
Even prescribed fires, often touted as an important wildfire mitigation technique, still produce smoke. Park’s team acknowledged that a whole suite of options would be needed to minimize future wildfire deaths, ranging from fire-resilient forest and urban planning to PM2.5 treatment advances in hospitals. And, of course, there is addressing the root cause of the increased mortality to begin with: our warming climate.
“To respond to these long-term changes,” Park told me, “it is crucial to gradually modify our system.”
On the COP16 biodiversity summit, Big Oil’s big plan, and sea level rise
Current conditions: Record rainfall triggered flooding in Roswell, New Mexico, that killed at least two people • Storm Ashley unleashed 80 mph winds across parts of the U.K. • A wildfire that broke out near Oakland, California, on Friday is now 85% contained.
Forecasters hadn’t expected Hurricane Oscar to develop into a hurricane at all, let alone in just 12 hours. But it did. The Category 1 storm made landfall in Cuba on Sunday, hours after passing over the Bahamas, bringing intense rain and strong winds. Up to a foot of rainfall was expected. Oscar struck while Cuba was struggling to recover from a large blackout that has left millions without power for four days. A second system, Tropical Storm Nadine, made landfall in Belize on Saturday with 60 mph winds and then quickly weakened. Both Oscar and Nadine developed in the Atlantic on the same day.
Hurricane OscarAccuWeather
The COP16 biodiversity summit starts today in Cali, Colombia. Diplomats from 190 countries will try to come up with a plan to halt global biodiversity loss, aiming to protect 30% of land and sea areas and restore 30% of degraded ecosystems by 2030. Discussions will revolve around how to monitor nature degradation, hold countries accountable for their protection pledges, and pay for biodiversity efforts. There will also be a big push to get many more countries to publish national biodiversity strategies. “This COP is a test of how serious countries are about upholding their international commitments to stop the rapid loss of biodiversity,” said Crystal Davis, Global Director of Food, Land, and Water at the World Resources Institute. “The world has no shot at doing so without richer countries providing more financial support to developing countries — which contain most of the world’s biodiversity.”
A prominent group of oil and gas producers has developed a plan to roll back environmental rules put in place by President Biden, The Washington Post reported. The paper got its hands on confidential documents from the American Exploration and Production Council (AXPC), which represents some 30 producers. The documents include draft executive orders promoting fossil fuel production for a newly-elected President Trump to sign if he takes the White House in November, as well as a roadmap for dismantling many policies aimed at getting oil and gas producers to disclose and curb emissions. AXPC’s members, including ExxonMobil, ConocoPhillips, and Hess, account for about half of the oil and gas produced in the U.S., the Post reported.
A new report from the energy think tank Ember looks at how the uptake of electric vehicles and heat pumps in the U.K. is affecting oil and gas consumption. It found that last year the country had 1.5 million EVs on the road, and 430,000 residential heat pumps in homes, and the reduction in fossil fuel use due to the growth of these technologies was equivalent to 14 million barrels of oil, or about what the U.K. imports over a two-week span. This reduction effect will be even stronger as more and more EVs and heat pumps are powered by clean energy. The report also found that even though power demand is expected to rise, efficiency gains from electrification and decarbonization will make up for this, leading to an overall decline in energy use and fossil fuel consumption.
Ember
The world’s sea levels are projected to rise by more than 6 inches on average over the next 30 years if current trends continue, according to a new study published in the journal Nature. “Such rates would represent an evolving challenge for adaptation efforts,” the authors wrote. By examining satellite data, the researchers found that sea levels have risen by about .4 inches since 1993, and that they’re rising faster now than they were then. In 1993 the seas were rising by about .08 inches per year, and last year they were rising at .17 inches per year. These are averages, of course, and some areas are seeing much more extreme changes. For example, areas around Miami, Florida, have already seen sea levels rise by 6 inches over the last 31 years.
“As the climate crisis grows more urgent, restoring faith in government will be more important than ever.” –Paul Waldman writing for Heatmap about the profound implications of America becoming a low-trust society.