In the desert heat of Kandahar, Afghanistan, where the asphalt cooks and air conditioners wheeze in surrender, Afghan taxi drivers have taken a cue from Ancient Persia. Temperatures are now over 104 degrees and air con repairs are too expensive. Forget Tesla’s climate control or fancy freon-fueled chillers—these drivers are mounting DIY windcatchers on their car roofs and turning their beat-up Toyotas into eco-cooling machines. The cost? $43.

Call it badgir 2.0: A clever, water-cooled evaporative system rigged from plastic jugs, PVC pipe, swamp-cooler pads, and a 12V pump, all held together by hope and centuries-old wisdom.

These contraptions—locally called “badnivil”—aren’t just a funky roadside gimmick. They’re actually working better than factory-installed AC in dry climates, cooling the entire cab and earning high praise from passengers, who now prefer the “natural AC” over the old mechanical kind.

“With these coolers, you feel the breeze everywhere,” says one driver in a now-viral AFP video. “The AC just blows cold at the front. This is more like nature.”

Related: 5 ways to use air conditioner water

These rooftop air chillers are inspired by windcatchers—tall structures in Persian architecture designed to funnel and cool breezes into homes, often enhanced with water or ice for maximum effect. Combine that principle with a little MacGyver spirit, and you’ve got Kandahar’s answer to climate adaptation on four wheels.

While the world waits for billion-dollar innovations to solve heat resilience, these Afghan tinkerers have already built theirs—for about $15. Afghan opium producers also rely on solar energy to grow poppies.

So… Want to Make Your Own McGyvered air con for your car?

You don’t need to be in Kandahar—or even be particularly handy—to build a mini version for your car. Here’s a stripped-down DIY guide to create your own Afghan-style windcatcher cooler. No tech degree or camel required.

?️ DIY: Afghan-Style Evaporative Car Cooler

What You’ll Need:
Item Notes

20L plastic water tank or jerry can (mounts on roof or trunk)
Swamp cooler pad / burlap / sponge (acts as the cooling surface)
Small 12V submersible pump (available online or at garden shops)
Flexible tubing or hose to circulate water
Ducting or vent hose to channel cooled air inside
Mesh screen keeps bugs out, air in
Basic tools, zip ties, sealant for rigging and mounting
Optional: solar panel to power the pump without draining your battery

How Jerry-rigged AC Works

The pump draws water from the tank and keeps the cooling pad wet.

As the car moves (or from natural breeze), air blows through the wet pad.

Water evaporates, heat disappears, and cool air is piped inside.

Because your AC runs on water and physics—not gasoline.

Build Instructions (simplified)

Mount a plastic box or crate on the car roof with airflow holes on both sides. Stuff it with wet cooling pads, burlap, or even old T-shirts—just keep them moist.

Run tubing from a small water tank (placed nearby) to a pump that trickles water onto the pad.

Connect a duct from the back of the box down into your cabin (through a window or vent).

Power your pump via your car battery or a tiny solar panel.

Enjoy the quiet hum of sustainability while everyone else melts in traffic.

Pro tip: If your city is humid, this won’t work as well—evaporative cooling is most effective in dry desert air. For urban use, pair it with a small fan for airflow boost.

The Afghan windcatcher car cooler isn’t just clever. It’s low-cost climate adaptation. With rising global temperatures and millions of cars still without functioning air con, it’s a design-for-the-rest-of-us moment. A punk rock move in a world of overdesigned heat tech. Plus, it’s deeply sustainable: no refrigerants, no increased fuel use, no carbon guilt. Just water, airflow, and a little DIY spirit.

My friends in the hot and dry Negev Desert own a Desert Cooler mounted on the roof to keep their home cool, and delightfully more humid in the hot, desert and dry sun. Why these have fallen out of fashion is anyone’s guess.

The post Afghan Taxis Get Ancient Persian A/C Hack—And It Works Better Than Yours appeared first on Green Prophet.

We’ve written about the benefits of white paint on a hot tar roof in the past, at least a couple of times. And the fact that they can’t slow global warming.  White paint is what people paint the roofs of their apartment buildings in Tel Aviv to keep the insides cool. It’s certainly something that designers and architects in the Middle East already know and that’s why mashrabiya were invented.

People in the Middle East or Texas who don’t want to enter an inferno 6 months of the year buy white cars. And if you have a black roof home or even a panel of glass windows that face the sun, expect to have your air conditioner bill go through the roof for 6 months of the year.

Some more research from Purdue and a “new” white paint, which is the whitest of the white paint, explores just how much you can save by painting your roof white. This is a great idea for energy savings on large industrial buildings, schools, hospitals, factories and government buildings looking to lower energy costs. They say that their experimental paint is so effective you might never need to turn your air con on. And after the new white roof? Maybe a rooftop garden? Solar energy panels?

Back over to the study: Purdue University engineers have created white paint that can keep surfaces up to 18 degrees Fahrenheit cooler than their ambient surroundings – almost like a refrigerator does, but without consuming any energy. We call this passive cooling. 

According to the researchers, the paint would replace the need for air conditioning by absorbing nearly no solar energy and sending heat away from the building. Without the building heating up, air conditioning wouldn’t have to kick on.

“It’s very counterintuitive for a surface in direct sunlight to be cooler than the temperature your local weather station reports for that area, but we’ve shown this to be possible,” said Xiulin Ruan, a Purdue professor of mechanical engineering.

The paint not only sends heat away from a surface, but also away from Earth into deep space where heat travels indefinitely at the speed of light. This way, heat doesn’t get trapped within the atmosphere and contribute to global warming. 

Sci Fi White Paint Video:

“We’re not moving heat from the surface to the atmosphere. We’re just dumping it all out into the universe, which is an infinite heat sink,” said Xiangyu Li, a postdoctoral researcher at the Massachusetts Institute of Technology who worked on this project as a Ph.D. student in Ruan’s lab.

Earth’s surface would actually get cooler with this technology if the paint were applied to a variety of surfaces including roads, rooftops and cars all over the world, the researchers said.

In a paper published Wednesday (Oct. 21) in the journal Cell Reports Physical Science, the researchers show that compared with commercial white paint, the paint that they developed can maintain a lower temperature under direct sunlight and reflect more ultraviolet rays.

Their proof is infrared camera images taken of the two paints in rooftop experiments.

“An infrared camera gives you a temperature reading just like a thermometer would to judge if someone has a fever. These readings confirmed that our paint has a lower temperature than both its surroundings and the commercial counterpart,” Ruan said.

Reflects most of the sun’s heat

Commercial “heat rejecting paints” currently on the market reflect only 80% to 90% of sunlight and cannot achieve temperatures below their surroundings. The white paint that Purdue researchers created reflects 95.5% sunlight and efficiently radiates infrared heat.

Developing this paint formulation wasn’t easy. The six-year study builds on attempts going back to the 1970s to develop radiative cooling paint as a feasible alternative to traditional air conditioners.

Making the whitest of the white from seashells

The researchers considered over 100 different material combinations, narrowed them down to 10 and tested about 50 different formulations for each material. They landed on a formulation made of calcium carbonate, an earth-abundant compound commonly found in rocks and seashells.

This compound, used as the paint’s filler, allowed the formulation to behave essentially the same as commercial white paint but with greatly enhanced cooling properties. These calcium carbonate fillers absorb almost no ultraviolet rays due to a so-called large “band gap,” a result of their atomic structure. They also have a high concentration of particles that are different sizes, allowing the paint to scatter a wider range of wavelengths.

According to the researchers’ cost estimates, this paint would be both cheaper to produce than its commercial alternative and could save about a dollar per day that would have been spent on air conditioning for a one-story house of approximately 1,076 square feet.

“Your air conditioning kicks on mainly due to sunlight heating up the roof and walls and making the inside of your house feel warmer. This paint is basically creating free air conditioning by reflecting that sunlight and offsetting those heat gains from inside your house,” said Joseph Peoples, a Purdue Ph.D. student in mechanical engineering and a co-author of the work.

Cutting down on air conditioning also means using less energy produced by coal, which could lead to reduced carbon dioxide emissions, Peoples said. The researchers have further studies underway to evaluate these benefits.

Environmental artist and designer Pablo Solomon lives in the hot and arid American state of Texas. He doesn’t believe that white paint could put air conditioners out of commission in Houston:

“While painting surfaces white does reflect sunlight, it will not replace AC in Houston, Texas. Having lived much of my early life there, the heat is made more miserable by the high humidity. Also, although Houston is 50 miles inland from the Gulf of Mexico, it is usually the first or second port by tonnage in the US due to it being accessible by the Houston Ship Channel being dredged from Buffalo Bayou and the San Jacinto River,” he tells Green Prophet.

He notes: “Houston’s weather is totally dominated and kept at subtropical warmth by the Gulf of Mexico. Normal humidity hovers around 80 plus percent. Downtown Houston is barely 50 feet above sea level and many of the suburbs toward the coast are less than that. Add all of the steel and concrete of America’s 4th largest city and AC is not a luxury, but a requirement.

“Thank heavens that new high efficiency AC units, double/triple paned windows and improved insulation cut energy use a lot. Also to put things in perspective, if you spin your home globe, you will see that Houston is the same latitude as Cairo and Saigon.”

___ 

Have a passive energy solution to report? Email me karin@greenprophet.com

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I dream of shade everywhere I walk, run or cycle and wonder why cities in hot climates don’t make a point to put shade everywhere. Sunny side of the street for me? Nope, I follow the paths that cast shadows from trees or nearby buildings. You get the point.

As we humans grow to understand why we need to make cities walkable, and comfortable, the big issue of shading hot cities is a big one.

Architects building shady, flowery canopies for Hajj got the message. And now, Israel’s Design Museum of Holon started a competition for encouraging architects to develop projects for urban shade.

Winners were Point Supreme Architects, an architecture firm from Athens, Greece.

See the sketches above and below for their winning design Serpantina:  public urban spaces that could be made in the shade.

The design is expected to be built in Tel Aviv, Israel by next year.

Serpantina is a simple linear element made up of modules of standard metal profiles and sun shading fabrics widely available in the market that can be both easily reproduced, adapted to different locations, transported and assembled on site.

More details:

Project details:

status: competition 1st prize
area: 300 m2
location: Tel Aviv, Israel
structural engineer: Athanassios Kontizas
local architect: Robert Ungar
collaborator: Reineke Otten
client: Beracha Foundation and Design Museum Holon
expected completion: June 2015

The post Made in the shade with simple, cheap urban design for Tel Aviv appeared first on Green Prophet.

The designers of Passivhaus (or Passive House in English) aim to demonstrate that their building will double the “greenness” of a comparable home built to Qatar’s existing green rating system – Global Sustainability Assessment System (GSAS).  Can a house designed to be “hot” also be “cool”?

The Passivhaus design (or passive house) is an adaptation of a German concept, newly modified for Qatar’s punishing climate. In the 1990’s, two German researchers developed specifications for a building whose thermal mass and super insulation could protect its interior from a harsh external climate. Their strategy was proven to work in cold environments. Researchers are now exploring how it pans out in extreme heat and humidity.

The project pits two 225 square meter (2,745 square foot) single-story villas against each other to determine which guzzles more energy and water. Over a six month test period, a family of four will reside in both buildings – each with similar layouts, fixtures, and appliances. The study is part of a 2-year, $665,000 project, underwritten by the Qatar National Research Fund.

On one corner, Passivhaus features airtight construction and high-efficiency air conditioning. Heat-gain and daylighting are passively controlled via small windows and skylights with high performance glazing. Roof-mounted solar panels generate renewable energy, with any surplus electricity sent back to the national power grid – a first for this Persian Gulf nation. Bioreactor tanks which clean and recycle water have also been installed.

On the other corner, a conventional villa, named “Baytna” (Arabic for “our house”), was built to a one-star GSAS standard using standard construction methods.

Although GSAS guidelines make this building greatly more efficient than most Qatari homes, researchers predict that this house will consume 50% more energy and water and 50% more carbon dioxide emissions compared with Passivhaus.

But enough with predictions – time to put this to the test. This autumn, same-size families will move into each home to compare energy use and carbon footprint.

A team from the Texas A&M University at Qatar will monitor and analyze the families’ energy use and water consumption, and track performance of equipment and materials used in each of the houses.

After six months, the families will be trained on how to live eco-friendly lifestyles before allowing them to stay for another six months.  That phase of the project will observe how behavioral modification impacts resource consumption. (This screams to be sold as a geeky reality show – one I’d happily tuck in to.)

Dr. Alex Amato, head of sustainability at Qatar Green Building Council (QGBC), said the live-in experiment was chosen to produce more true-to-life findings than using a computer-simulated test.  “If we can achieve success, the next step will be to see how we can reward people for their behavior, and to expand the program for existing houses and new neighborhoods,” he said in a statement on the Qatar Foundation website.

He believes that cost of adopting Passivhaus standards for Qatar’s climate can be reduced if prefabrication and off-site manufacturing are maximized.

“Sustaining economic growth is not possible without a vision that…balance(s)…economic development and protection of the environment,” said Ahmad Al-Abdulla, Deputy Group CEO at Barwa Real Estate Group (BRE).

This project, which seeks to create a model for the home of the future, is the brainchild of the QGBC,  BRE and Qatar General Electricity & Water Corporation (Kahramaa).  Good stuff, but what’s how do those lush green lawns fit into the sustainable equation?

The post Will Qatar’s Passivhaus Baytna experiment perform in intense heat? appeared first on Green Prophet.

Green Prophet loves to find potential everywhere – so how about desert seawater greenhouse construction in Qatar? They are also doing this in Abu Dhabi.

What exactly is a desert seawater greenhouse, you might ask?

According to the Seawater Greenhouse website: “Seawater Greenhouse is a unique concept which combines natural processes, simple construction techniques and mathematical computer modeling to provide a low-cost solution to one of the world’s greatest needs – fresh water.

“The Seawater Greenhouse is a new development that offers sustainable solutions to the problem of providing water for agriculture in arid, coastal regions.”

In layman’s terms, the seawater greenhouses use seawater to humidify the air in the greenhouse while sunlight distills the fresh water out of the seawater. This is a unique solution for desert areas where fresh water is scarce.  It is especially great for Middle Eastern countries, many of which have access to saltwater and have large areas of desert land. But it sort of also feels like a country in the west is borrowing ideas long ago practiced in the Middle East and calling it “new.”

Seawater greenhouse Powered by the Sun

But beyond being practical, the use of desert seawater greenhouses is greener than the alternatives for a couple of reasons.  Firstly, traditional desalination projects are energy intensive and consume lots of fossil fuels.

Once constructed, desert seawater greenhouses are solar powered.  Secondly, in enabling more desert areas to be used for agriculture, local agriculture is encouraged and fewer food products may be imported from far away (thus reducing a nation’s food carbon footprint).

According to Charlie Paton, the inventor of Seawater Greenhouse technology, “UAE, Bahrain, Oman, Abu Dhabi and Kuwait are other countries in the region which are planning to turn its vast areas of arid lands into arable through the unique method.”

Read more about how Qatar’s neighbors are exploring alternative energies
Solar Technologies FZE Plans to Build Middle East’s Largest Solar Panel Plant in Dubai
Dubai’s Wind Powered Rotating Skyscraper is Building in Motion
A Green Survey of Dubai and the United Arab Emirates

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According to research by the Department of Energy shade trees can reduce the need for air conditioning by 7% to 40%. If you have a garden, plant a tree. It can decrease the energy you need to cool your space but also provide a place to hang a tire swing, not to mention the offsets.

If you don’t have a garden plant vines in a window box. They grow nicely over security bars. This way you can disguise the ugliness and give yourself beautiful flowers as well!

While plastic awnings offer a basic shade solution, they lack the natural benefits that trees provide in terms of air circulation and ventilation.

One of the key advantages of trees is their ability to facilitate airflow through their branches and leaves. Unlike plastic awnings, which block airflow and can create stagnant pockets of hot air underneath, trees allow breezes to pass through, creating a cooling effect. The movement of air through a tree’s canopy helps to dissipate heat and humidity, making the shaded area feel more comfortable even on the hottest days.

Additionally, trees can act as natural air purifiers, filtering out pollutants and allergens from the air. As air moves through the leaves and branches, particles such as dust, pollen, and pollutants are trapped, improving air quality in the surrounding area. This is especially beneficial for individuals with respiratory issues or allergies, as it can help to reduce symptoms and improve overall well-being.

Read Also: 5 tips for reusing air conditioning water

Moreover, trees play a crucial role in regulating microclimates within their vicinity. By providing shade and cooling the surrounding air, trees help to create a more stable and pleasant outdoor environment. This is particularly important in urban areas, where the urban heat island effect can lead to higher temperatures and increased discomfort. Trees can help to mitigate this effect by shading pavement and buildings, reducing the absorption of heat and lowering ambient temperatures.

In terms of functionality, trees offer several advantages over plastic awnings when it comes to airflow. The natural shape and structure of a tree’s canopy are optimized to maximize airflow and ventilation. The leaves and branches are arranged in such a way as to allow air to move freely through the canopy, creating a gentle breeze underneath. This natural ventilation system helps to keep the shaded area feeling fresh and comfortable, even on still days when there is little wind.

Furthermore, trees provide shade not only for people but also for buildings and other structures. By shading rooftops and walls, trees help to reduce solar heat gain and lower indoor temperatures. This can significantly reduce the need for air conditioning and ventilation, leading to energy savings and lower utility bills. In contrast, plastic awnings only provide shade to the areas directly beneath them, without offering any additional benefits to surrounding structures.

The post Plant Some Shade – Why trees are better than artificial shade appeared first on Green Prophet.