Passive Cooling in a Tiny House
Originally published on RMI.org.
By John Matson
As the world warms and the demand for cooling increases, many homes will require an “all of the above” approach to keep cool without further contributing to global warming. That can include high-performance cooling systems that use climate-friendly coolants and consume relatively little energy, as well as building design approaches that offset the need for mechanical cooling in the first place.
This tiny, ultra-efficient Passive House was built in just 10 days in #Australia http://t.co/glUiZVSN1o pic.twitter.com/pjYxo496ti
— The Architect’s Newspaper (@archpaper) February 10, 2015
In this post, we look at some passive cooling strategies that help keep an innovative tiny house comfortable during California summers, without the use of a mechanical cooling system.
Brett Webster, a manager in RMI’s Carbon-Free Buildings program, lives in a 170-square-foot home in Sonoma County, California. Brett and his partner helped design and build the solar-powered tiny house as part of a graduate project, and they have lived in the demonstration home for about five years. The home itself was built on a 24-foot-long trailer and can be hitched up to a truck for relocation. So even though Brett and his partner have lived in their tiny home for years, they have moved twice in that time between Northern California locations (and their respective microclimates).
Strategic Shading
The walls of the tiny house are clad in reclaimed cedar slats over one-inch-thick panels of cork, which provides a layer of continuous insulation, reducing the thermal bridging of the wooden wall framing. Because the carbon sequestered in cork trees can exceed the carbon emissions of producing cork products, cork is often considered a carbon-negative material. The cedar siding is separated from the cork by an air gap, which allows the wooden slats to shade the cork and absorb solar radiation, while slowing the rate of heat transfer directly to the house. The walls of the structure are insulated with recycled denim to further limit heat gain in warm weather and heat loss in cool weather.
Pulley-mounted shade awnings, made from cedar slats to match the siding, cover the largest expanse of glass on the tiny house: a sliding-glass door at the entry to the home. Webster says that the shade structure extends far enough to block solar radiation from pouring through the glass entryway in summer, but it can let in sunlight and heat in winter, when the sun is lower in the sky.
The ability to shade the windows in summer and admit sunlight during the winter is critical to maintaining passive comfort in the house. The windows that the design team chose for the tiny house are well-insulated (low U-value) but are also designed to let the sun’s heat in (high solar heat gain coefficient), because the Bay Area is mostly a heating-dominant climate zone. During the summer, when that heat gain is not desirable, shading the windows is a necessity.
Ceiling and Roof
A layer of BioPCM phase change material in the ceiling acts like thermal mass to absorb and store heat that would otherwise warm the interior space. Adobe buildings and concrete-walled structures similarly benefit from thermal mass that prevents the interior from becoming overheated during the day. But phase change material is lightweight, making it more appropriate for applications like the ceiling of a tiny house, and it doesn’t have the carbon footprint of concrete. (Cement production alone accounts for about 8 percent of global carbon emissions.)
The phase change material, which comes embedded in sheets that can be rolled out between ceiling joists like high-tech bubble wrap, melts from solid to liquid at 77 degrees F (25°C). As it changes phases, the material absorbs a lot of thermal energy, preventing the temperature from exceeding 77 degrees until its heat-absorbing capacity has been reached, like a sponge that can’t soak up any more water.
The tiny house’s roof is designed to harness much of the sun’s energy and reject the rest. A 2.3-kilowatt solar array shades much of the tiny house’s roof and feeds into a Tesla Powerwall to store electricity for nighttime use. The “cool roof” is also covered with a light-colored acrylic roofing membrane to minimize heat gain from solar radiation.
Some Energy Required (But Not Much)
In addition to the passive cooling approaches described above, the tiny house relies on a few efficient electric devices to provide airflow and ventilation. Even though they don’t qualify as strictly “passive” technologies, ceiling fans and other efficient electric devices have long gone hand-in-hand with passive cooling approaches. The ventilation and airflow systems in the tiny house consume very little energy and allow the building to remain comfortable without a dedicated mechanical cooling system.
A high-efficiency overhead ceiling fan consumes 4–18 watts of electricity and ensures occupant comfort in warmer temperatures. “Airflow creates a cooling sensation that’s extremely effective,” Webster says. According to the US Department of Energy, using a ceiling fan can significantly offset the need for air conditioning, allowing occupants to raise the thermostat by about 4 degrees F without sacrificing comfort.
The well-insulated structure is designed to be closed off to the outside during hot days in the summer, so the windows do not provide any natural ventilation during the daytime. The tiny house therefore relies on an energy recovery ventilator to bring fresh air into the house. An energy recovery ventilator uses a heat exchanger to reduce the thermal energy of the outside air before it enters the house, thereby providing ventilation without flushing warm air into the building. In the winter, it does the reverse, using the heat of the outgoing stale air to warm the incoming fresh air.
Unplugging
The tiny house’s passive design and minimal energy requirements for ventilation make it fully capable of going off-grid, especially in the summer months when solar energy is abundant. And even if most of us aren’t ready to commit to living in a 170-square-foot house on wheels, the lessons from Webster’s tiny house and other passive homes provide a powerful reminder: Even for energy-intensive applications like cooling, with thoughtful design, you can do a lot with a little.
Image gallery courtesy of RMI.
![Classic Jeep Grand Wagoneer gets a battery electric makeover [video]](https://i0.wp.com/electrek.co/wp-content/uploads/sites/3/2025/11/grand-wagoneer_EV_2.jpg?resize=1200,628&quality=82&strip=all&ssl=1)
Texas-based tuning firm Vigilante 4×4 is known for its wild, high-horsepower Jeep SJ Hemi restomods – but they’re more than just a hot rod shop. To prove it, they’ve developed a bespoke, all-electric skateboard chassis designed to turn the classic Jeep Grand Wagoneer into a modern, desirable electric SUV.
The scope of the Vigilante 4×4 electric chassis project is truly impressive. More than just a Jeep SJ frame with an electric drive train bolted in, the chassis is a completely fresh design that utilizes precise 3D scans of the original SJ Wagoneers, Grand Wagoneers, and J-Trucks to establish hard points, then fitted with low-slung battery packs to give the electric restomods superior weight balance, a lower center of gravity, and objectively improved ride and handling compared to its classic, ICE-powered forefathers.
The result is a purpose-built platform that delivers power to the wheels through a dual-motor system – one mounted in the front, and one at the rear – to provide a permanent, infinitely variable four-wheel drive system that offers both on-road performance and the kind of off-road capability that made the Grand Wagoneer famous in the first place.
Vigilante 4×4 electric Jeep SJ
“This isn’t a replacement for our Vigilante HEMI offerings,” reads the official copy. “It’s a total revisit of the Vigilante platform under electric power.”
The company emphasizes that its new chassis is still in the prototype stages. As such, there are no specs, there is no pricing, there are no range estimates. Despite it all, the response from Jeep enthusiasts has already been strong. “Keep in mind this is our first prototype,” a spokesperson said. “There’s still a lot of work to be done – but the journey has begun.”
Electrek’s Take
Retro done wrong – think the Dodge Charger Daytona EV or VW ID.Buzz – is a disaster. Always. If that nostalgic tone is just a little bit off, the song doesn’t work. The heartstrings don’t pull. Done right, however, the siren song of nostalgia will have you putting a second mortgage on your house to put a Singer Porsche or ICON Bronco in your garage.
It’s too soon to tell what side of that line the Vigilante 4×4 Jeep SJ will eventually fall, but one thing (at least) is certain: it’s closer to the mark than that Wagoneer S.
SOURCE | IMAGES: Vigilante 4×4, via Mopar Insiders.
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EQORE, a distributed battery storage startup based in Somerville, Massachusetts, has raised $1.7 million in seed funding to help industrial buildings tackle rising electricity costs. The round was oversubscribed and includes backing from the Massachusetts Clean Energy Center (MassCEC), Henry Ford III of Ford Motor Company, and Jonathan Kraft of The Kraft Group.
The timing couldn’t be more relevant. Data centers are booming, and that demand is slamming an already stressed grid. Big, utility-scale batteries help at the grid level, but they can’t fix the bottlenecks happening on local distribution networks. That’s where onsite storage steps in — storing energy when demand is low and discharging it when demand spikes, which helps stabilize costs for both the grid and the businesses using it.
MassCEC’s head of investments, Susan Stewart, said, “What excites us the most about EQORE’s technology is the dual impact: grid support and customer savings.” She noted that commercial and industrial buildings are ideal hosts for battery storage, but haven’t gotten much attention until now. “EQORE is closing that gap.”
Investor Randolph Mann highlighted what makes the company stand out: “By uniting advanced controls with high‑resolution metering and true end‑to‑end service, EQORE finally makes commercial behind-the-meter storage effortless and financially compelling for businesses.”
EQORE comes out of MIT’s Sandbox program and delta v accelerator and is currently part of the Harvard Climate Entrepreneurs Circle incubator. CEO and cofounder Valeriia Tyshchenko, a third‑generation engineer from Ukraine and MIT graduate, said the new funding will help the company scale alongside its existing revenue.
With the seed round closed, EQORE plans to grow its team and ramp up battery deployments at energy-intensive manufacturing facilities. The company doesn’t just install batteries; it operates them. Its autonomous software shifts when a facility uses power based on market conditions and utility incentives, reshaping load in real-time without disrupting operations.
Read more: Battery boom: 5.6 GW of US energy storage added in Q2
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![Check out Hyundai's cool new off-road electric SUV concept [Images]](https://i0.wp.com/electrek.co/wp-content/uploads/sites/3/2025/11/Hyundai-off-road-SUV.jpeg?resize=1200,628&quality=82&strip=all&ssl=1)
Hyundai took the sheets of its new off-road electric SUV, the Crater Concept, at the LA Auto Show. Here’s our first look at the compact off-roader.
Meet Hyundai’s new off-road SUV, the Crater Concept
We knew it was coming after Hyundai teased the off-road SUV earlier this week, hidden under a drape. Hyundai took the sheets off the Crater Concept at the LA Auto Show on Thursday, giving us our first real look at the rugged off-roader.
Hyundai refers to it as a compact off-road SUV that’s inspired by extreme events. The concept was brought to life at the Hyundai America Technical Center in Irvine, California.
The off-road SUV draws design elements from Hyundai’s Extra Rugged Terrain (XRT) models, such as the IONIQ 5 XRT, Santa Cruz XRT, and the new Pallisade XRT Pro.
Although it’s a concept, Hyundai said the Crater Concept is a testament to its commitment to designing future XRT vehicles that are more functional, more capable, and more emotional.
“CRATER began with a question: ‘What does freedom look like?’ This vehicle stands as our answer,” Hyundai’s global design boss, SangYup Lee said.
The off-road SUV features Hyundai’s new Art of Steel design theme, first showcased on the THREE concept at the Munich Motor Show in September.
Hyundai said the design team was guided by one clear goal: To create a rugged and capable vehicle that’s designed to go anywhere. The Crater Concept embodies that vision with added wide skid plates, 33″ off-road tires, limb risers, rocker panels, and a roof platform.
Hyundai designed the interior for “tech-savvy adventure seekers,” with a singular design centered around a high-brow crash pad that stretches across the dashboard.
The concept also swaps the traditional infotainment setup for a head-up display that spans the entire front window, which Hyundai said includes a live rearview camera.
Hyundai’s off-roader includes a new Off-Road Controller for front and rear locking differentials, as well as a terrain selector with modes including Sand, Snow, and Mud. Other off-road features include downhill brake control, trailer brake control, a compass, and an altimeter.
Although Hyundai said it was electric, it didn’t reveal any further details about the powertrain. The off-road SUV could be a battery-electric or fuel-cell-electric vehicle.
Like the new Nexo, Hyundai’s hydrogen fuel cell vehicle, the concept features “HTWO” lamps exclusive to its FCEVs.
Earlier this week, the design team at Hyundai Design North America also introduced its new design and ideation studio codenamed “The Sandbox.” The creative design studio is set to serve as a global hub for future XRT vehicles and gear.
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