LOW←TECH MAGAZINE English

Rediscovering the Handcart

Wed, 22 Apr 2026 00:00:00 +0000

Image: The handcart, equipped with a sail. Photo by Kris De Decker.

The human-powered handcart is the oldest of vehicles, and it will likely be the last one around in the future. Of all vehicles, it’s the cheapest and least complex to build and use. It offers a large advantage over carrying a load on your back or dragging it over the ground - the even older concept of the sled. On the other hand, the handcart is cheaper and easier to use than the animal-powered cart. Oxen and donkeys eat more than humans, and they have their own will, which can work against the driver.

Like any other wheeled vehicle, the handcart requires roads to drive on. This infrastructure has not always been available anywhere or at any time in history. For example, in medieval Europe, porters and pack animals were more common than handcarts because of poor roads. ¹ In the West, the handcart only reached its heyday during the first decades of the Industrial Revolution, when it connected fast-growing cities to train stations and harbors. In China, on the other hand, the handcart was the backbone of the transport network for millennia. ²

Of all vehicles, the handcart is the cheapest and least complex to build and use.

There are still many human-powered carts in modern society: strollers, grocery carts, roller suitcases, and various utility and folding carts. However, these modern carts are to their predecessors what birds are to dinosaurs. They are small, often with very small wheels, and we use them for very short distances, usually inside buildings. In contrast, old-fashioned handcarts were often large and had big wheels, and they were pushed or pulled on roads and over longer distances. Many crafts and professions had their own type of handcart.

Image: Low-tech Magazine's handcart. Photo by Kris De Decker.

Why I need a handcart

People still use large handcarts in so-called “developing countries”. However, they can be just as useful again in the large cities of the industrialized world, as I can testify after using one for a couple of months. Last autumn, I received an internship application from Kozimo, who studies at the Design Academy Eindhoven. In his application, Kozimo sent a video of a large handcart he made, which he was driving on the streets of Rotterdam, the Netherlands.

I have always dreamt of a handcart. I have never owned a car, and the only times I miss one are when I have to move stuff, something which has become increasingly common lately. Consequently, I proposed to Kozimo to build a handcart for me.

Now, I can no longer imagine living without it. I have used the vehicle to move houses and offices, pick up materials and objects I bought online, new or second-hand, and transport workshop and event materials (bike generators, solar panels, solar ovens, books, sound systems). I have done the same for friends. During these trips, I often took home materials, furniture, or objects that I found for free on the streets of Barcelona.

Image: Kozimo and Kris De Decker with Low-tech Magazine's handcart, halfway through a 30 km trip along the coast of Spain. Photo by Linda Osusky.

Unlike a van or a car, my handcart doesn’t need gasoline, electricity, or batteries, making it entirely independent from energy infrastructures. Neither do I need to pay taxes and insurance. The handcart is a very democratic vehicle. It allows anyone to carry a load wherever they want, while older, less affordable cars and vans are no longer allowed to enter city centers due to the installation of Low Emission Zones.

A handcart doesn’t need gasoline, electricity, or batteries, making it entirely independent from energy infrastructures.

It would make a lot of sense to offer vehicles like this at community centers, where they are available for all neighbors to use when needed. Few people would need a handcart each day, and communal use would solve the parking problem. Although our handcart can also be parked vertically, it won’t fit in most apartments.

Description of the handcart

This article will not explain in detail how to build a handcart. We want to do that another time with a simpler handcart model, because the vehicle we present in this article is not one that most people can make themselves. You need good woodworking and metalworking skills, and in fact, two people made the handcart.

Kozimo designed and built the whole structure from wood, while Guilhem Senges - visual artist and one of my neighbors - designed and made several essential reinforcements from metal; the wheels, the brakes, and the handlebars are all connected to the wood structure with custom-made iron parts.

Image: The underside of the handcart. Photo by Kris De Decker.

Images: The front and back of the handcart. Photos by Kris De Decker.

Image: The lights are mounted in coconuts. Photo by Kris De Decker.

Load weight and volume

Low-tech Magazine’s handcart is 250 cm long and 100 cm wide, while the platform itself measures 210 by 85 cm. Assuming a load height of 50 cm, the cargo volume is roughly 1.55 m3 (37 cubic feet or 1050 liters). That’s two to four times the typical trunk space in a European car. We have transported cargo that is wider or longer than the cart: a large heated table measuring 140x140cm, and several loads of wooden beams, each three meters long.

The load weight is limited by the wheels, which come from a wheelchair. They can support up to 150 kg. ³ The cart itself weighs 32 kg, so the practical maximum cargo weight is about 120 kg. The loading platform consists of slats with gaps between them, making it easy to secure various types of cargo.

Images: The handcart with various cargoes. Upper left: a 6m2 wooden floor and a chest. Upper right: 3-meter-long wood beams. Below: A heated table ready for transport.

It drives itself!

Over the past few months, we’ve learned that people have many misconceptions about handcarts. For example, you may think that pushing a handcart takes a lot of effort, perhaps based on your experience pushing supermarket carts through parking lots or pulling heavy suitcases through city centers (which is how I moved stuff before I had a handcart).

However, using the handcart can be so effortless - even when it’s heavily loaded - that it feels like you are not pushing at all. Once in motion, you can often guide it with one hand, and it sometimes feels like the cart is pulling you forward. It’s no exaggeration to say that pushing the handcart with a 100 kg load is more comfortable than walking while carrying a 10 kg heavy backpack.

Using the handcart can be so effortless - even when it’s heavily loaded - that it feels like you are not pushing at all.

There are several reasons for this light operation, rooted in physics. Each vehicle has to overcome three forces: rolling resistance, air resistance, and gravity. Air resistance is negligible at walking speed, meaning that a handcart user on flat terrain mainly needs to overcome rolling resistance. That’s the friction between wheels and road surface, a factor that’s largely independent of speed.

In contrast, air resistance increases with the square of speed. A cyclist, going at 15-20 km/h, already spends more effort overcoming air resistance than overcoming rolling resistance, which is the same in both cases because both vehicles have similar wheels. In short, the handcart’s low speed minimizes air resistance, while its narrow wheels minimize rolling resistance.

Image: Driving the handcart. Photo by Linda Osusky.

Second, accelerating a vehicle requires more energy than maintaining a constant speed. You only need to sustain momentum, not build it. Our handcart is pushed by a person walking, so the effort to accelerate lasts no longer than one or two seconds. In contrast, a cyclist takes much longer to reach cruise speed, and because of the higher air resistance, it takes more effort to sustain that speed. If the handcart is heavily loaded, it also gains significant kinetic energy, even at low speed. That explains why it sometimes feels like the cart is pulling you forward - because it actually is.

Finally, our wheels are much larger than those used on modern pushcarts. That makes for comfortable driving on asphalt and sidewalks, which are not as smooth as airport or supermarket floors. Large wheels increase air resistance, but because of our low speed, that doesn’t matter.

Handcarts and gravity

However, an effortless ride requires two conditions: flat terrain and a well-balanced load. Both involve the third force any vehicle must overcome: gravity.

Balancing the handcart: distributing the load

A two-wheeled cart becomes heavy and difficult to use when too much weight is placed on the front or back. Consequently, you need to load the vehicle so that the weight is equal on both sides of the wheels. That’s easy to check: the cart should remain in a horizontal position for several seconds without you touching it. If there’s just one piece of cargo, place it above the center of the wheels. If there are more things to carry, the total weight should be divided equally over the two sides. Finetuning the balance often involves moving a backpack from the front to the back of the cart, or vice versa.

You need to load the vehicle so that the weight is equal on both sides of the wheels.

A two-wheeled cart also needs additional support to keep it horizontal when parked, for instance, when loading or unloading cargo. Otherwise, the cart may suddenly flip to the other side. Our handcart carries four support beams, two on each side. When the cart is moving, they are in a horizontal position. When the cart is parked, we remove one or more beams and place them in a vertical position. Each beam can be set to a different length, allowing us to stabilize the cart on uneven terrain. We tighten the beams with screws.

Image: The handcart is parked with four supporting legs. Photo by Kris De Decker.

Image: Detail of the supporting beam holder. Photo by Kris De Decker.

Many people have asked us why we didn’t build a four-wheeled cart that wouldn’t need to be balanced. However, four wheels would double the rolling resistance and thus the effort required to push the cart. Furthermore, a four-wheeled cart is less maneuverable and more difficult to drive on uneven terrain. You also need to get two extra wheels, and you need to build a steering mechanism. Throughout history, the two-wheeled handcart (or one-wheeled handcart in the case of China) was much more common than the four-wheeled cart. ¹

Going uphill: you need help

An effortless ride also requires more or less flat terrain, which is what you get here in many parts of Barcelona. If you go up a steep slope, you suddenly feel the weight of the cart and its cargo. Climbing with a heavily loaded cart can be as strenuous as running up stairs or cycling at top speed. People tell us we should put an electric motor on the cart, and that’s perfectly possible.

However, we found a simpler solution: if necessary, we ask for help from another person. Our handlebars are wide enough for two or even three people to push together, which makes going uphill a lot easier. Adding an electric motor and a battery would significantly increase the vehicle’s weight, and it only makes sense if you regularly have to climb hills.

Going downhill: brakes

Going downhill, you have to counter gravity forces to prevent the handcart from hurling down a slope, which would be very dangerous. Rather than pushing the cart, you’ll have to pull it back instead. Here, cyclists have all the advantage, as they can use gravity to its full benefit during a descent.

We made going downhill a lot easier by adding bicycle brakes. In combination with the large wheels, the brakes also allow the handcart to be taken down sidewalk curbs or even stairs without damaging it. They double as a hand brake as well, by tightening two lashing straps around them. That allows leaving the cart unattended on a slope or in high winds.

Image: The brakes. Photo by Kris De Decker.

Handcarts go on the sidewalk

Many people assume that handcarts go on the road, with the cars, or on the cycling path. That’s not the case: you use it on the sidewalk. Legally, handcart users are in a similar position to other pedestrians pushing a smaller handcart, such as a stroller. The only difference is that, when they are forced onto the road because there’s no sidewalk or it’s blocked, handcart users should walk on the right side of the road, while other pedestrians should walk on the left. For now, the police have stopped us only once, and they were just curious.

Legally, handcart users are in a similar position to other pedestrians pushing a smaller handcart, such as a stroller.

We could find no traffic laws that limit the size of a handcart, at least not in the handful of countries we researched, including Spain. However, in practice, there are clear limits. If your vehicle is wider than the space between traffic bollards that keep cars out of pedestrian streets, all pedestrian zones will become inaccessible to you. You should also take into account other obstacles on the sidewalk, such as building scaffolding. Consequently, it’s rarely practical to build a handcart more than one meter wide.

Barcelona has very wide sidewalks in most of the city. We rarely have to share the road with cars or cyclists. Of course, that’s not the case in every city, and then the use of a handcart becomes less attractive. Using a handcart on the road or cyclepath is rather dangerous because other vehicles are much faster.

Image: Kozimo pushes the handcart through a narrow walkway. Photo by Kris De Decker.

Respecting other pedestrians

Driving a large handcart on the sidewalk demands your full attention. You don’t want to hit any infrastructure, and you surely don’t want to hit someone’s legs. You need to drive it with respect for other pedestrians and their pets (some dogs start barking at the vehicle). In general, the handcart is very safe to use because it travels at a very low speed. That makes accidents less likely in the first place and less impactful if they do happen. You also have a very good overview of your vehicle, much better than for a car or a bicycle. As long as you keep your eyes on the handcart, you are unlikely to hit anything or anyone.

However, our handcart is so silent that people don’t hear it coming. We added a bicycle bell to warn people, but we hope to find a better tune in the future: every vehicle needs its own type of sound. We also need a bell for oncoming pedestrians who are watching their phones while walking and expect others to make space. With the handcart, we cannot always make that space. Our handcart has front and rear lights as well, wired to a USB power bank mounted underneath the platform. Lights are very helpful on sidewalks, both day and night, as they make the vehicle more visible. Furthermore, lights are essential if you need to move onto the road after dark.

Images: Kris De Decker drives the handcart through Barcelona. Photos by Guillaume Lion.

Even in Barcelona, sidewalks can get crowded, and a busy sidewalk will slow down the vehicle considerably. With little chance to overtake someone, we tend to get stuck behind the slowest walkers.

A handcart is not a difficult vehicle to drive, but nowadays people in industrialized societies have no experience with it. Apart from driving it attentively, you also need to be careful when rounding blind corners (take the turn as wide as possible) and when you leave a garage or any other type of exit (pull rather than push the cart). By the time you see oncoming traffic, you already have 2 meters of your handcart on the road or around the corner.

Why not a bike trailer?

Almost everyone who sees the handcart for the first time asks the same question: how do you attach it to a bicycle? You don’t. You push it while walking. When we say that, there follows a silence. Pushing a handcart seems like one step too far back, even for people committed to living more sustainably. Why would you push a handcart if you could just as well use a much faster bike trailer, or a cargo bike?

In fact, there are several practical reasons to opt for a handcart rather than a bike trailer, and we have already mentioned many of them. First, a handcart lets you go anywhere a pedestrian can, while cyclists often need to get off their bikes and push them - just like a handcart. A handcart is also more agile. For example, although the cart is 2.5 meters long, it takes just two seconds and little space to turn it around and walk in the opposite direction from where you came from.

Why would you push a handcart if you could just as well use a much faster bike trailer, or a cargo bike?

A handcart can be built larger than a bike trailer as well. Although it’s perfectly possible to build a bike trailer the size of our handcart, its higher speed would pose much greater risk of accidents and damage, both to the cart and to other road users. As a bike trailer, it would also need to be made sturdier, and it would need a more elaborate mechanism to operate the brakes.

All this does not mean that bike trailers are a bad idea. We have used the handcart mainly for trips between 5 and 10 km, which comes down to one to two hours of walking. For longer distances, the bike trailer has the obvious advantage of speed. If you need to cover 40 km, you would need to travel eight hours with a handcart, compared to just two hours with a bike trailer.

Image: Guilhem Senges, who built the vehicle's metal parts, pushes the handcart to a welding job a few streets up in the neighborhood.

The merits of slow travel

However, when people ask us why we don’t use it as a bike trailer, we can also answer differently: why the rush? Deciding to travel with the slowest vehicle possible is subversive because it questions values we take for granted in the modern world, such as speed and utility.

To many people, walking a handcart seems like a waste of time, but our experience is exactly the opposite. Every trip is an adventure, and we always look forward to using it again. It’s a pleasure to drive the vehicle, more like steering a boat than driving a land vehicle. It’s easy to chat with other pedestrians, who tend to be very curious about our vehicle. Consequently, the trip takes even longer.

To many people, walking a handcart seems like a waste of time, but our experience is exactly the opposite.

Driving a handcart feels entirely different from using any other mode of transport. When people are walking, they usually cannot carry much with them, either in terms of weight or volume. In contrast, the handcart allows you to walk with a lot of stuff close at hand: drinks, food, a sound system, books, extra clothes. Furthermore, you have a large platform, which allows you to rest and invite others to do the same. It becomes a vehicle for wandering and roaming, and for connecting to other people.

Image: It's a pleasure to drive the vehicle, more like steering a boat than driving a land vehicle. Model: Rocío Sánchez. Photo by Kris De Decker.

Image: The handcart with rain protection. Photo by Kris De Decker.

Handcart Accessories

Once the handcart proved its utility as a cargo vehicle, Kozimo began designing and building additional structures to expand its uses. These objects make use of the slatted platform or the support beam design. Unfortunately, Kozimo’s internship ended before we could test all these extensions, but the little experience we gained by now shows that the handcart can be much more than just a cargo vehicle.

Passenger seat

The first, and perhaps most powerful addition, is a foldable seat. While our handcart can be - and usually is - operated by only one person, it’s ideally handled by two people, especially for longer voyages. Thanks to the seat, one person can push the cart while the other one rests in the vehicle.

As long as the road is flat, the extra weight of the passenger does not significantly increase the effort to push the cart. Consequently, two people can travel faster or farther in a single day. When climbing hills or bridges, the passenger gets off the seat. If necessary, he or she also helps to push the cart.

One person can push the cart while the other one rests in the vehicle, increasing the distance that two people can travel in a day.

An extra pair of eyes on the road is also handy. The seat can be put in two positions, so that both the passenger and the driver are either looking in the same direction or facing each other, which makes it easier to talk and allows the passenger to serve as the rear-view mirror.

We used the seat on a 30 km day trip along the coast of Catalunya, Spain, moving stuff from my old place to my new place. For one person, this would have been an exhausting trip. However, there were several people on the way there, and two people on the way back. The fact that we could rest from time to time - without stopping - made a great difference, especially on the way back. An extra person also proved useful when unexpected obstacles arose. For example, there was a bridge under repair, which forced us to carry the cart down the rocks, over the beach, and up the rocks again.

Image: A foldable seat on the slatted platform. Photo by Kris De Decker.

Image: Kozimo drives the handcart along the coast. Linda Osusky is filming while resting in the seat. Photo by Kris De Decker.

Images: Carrying the handcart over the rocks. Photos by Linda Osusky.

Digital nomad office

As a second addition, we combined the seat with a work table that doubles as a solar power plant, resulting in a digital nomad office. The table fits onto the sides of the handcart and slides back and forth. The solar panel can be in a horizontal position or at various tilted angles. It can charge a laptop or any other device requiring up to 100 watts of power.

If you’re two people traveling, one person can work at the table while the other drives. If you’re alone, you can wheel the vehicle to the nearest park or beach, set up the four support legs, and work all day. In 2016, I took my home office off the grid with solar panels on the window sills. ⁴ Ten years later, both the office and the solar panels have become mobile.

Images: Digital nomad office. Photos by Kris De Decker.

Image: Digital nomad office. Photo by Kris De Decker.

Renewable power plant

Although we built only one solar panel support structure, the handcart platform is large enough to support a total of four 100-watt solar panels. That would provide us with 400 watts of solar power for a concert or emergency power, for example. The handcart can also transport the two bike generators Low-tech Magazine has in Barcelona. ⁵Consequently, the cart enables us to quickly provide power within a radius of several kilometers, at any time of the day. The handcart could also be wheeled into a sunny spot during the day, charging a battery bank to power a household during the night and in bad weather.

Mobile home

If you want to get back home the same day, the handcart’s range is roughly 40-80 km (8-16 hours of walking, back and forth). However, at least in my case, nobody obliges me to come back home the same day. I could use the handcart for longer voyages, especially since it offers me a place to sleep.

The four supporting legs that make loading and unloading the cart more practical can also be used to turn the vehicle into a bed. After Kozimo went back to the Netherlands, I bought a foldable mattress that fits neatly on the platform. During a trip, I can store the other cargo under the cart at night. Alternatively, I could push a passenger who’s lying in the bed, turning the vehicle into an adult version of a baby stroller.

Images: A foldable sleeping mattress on the handcart. Photos by Kris De Decker.

Image: A mosquito net covers the handcart with a sleeping mattress. Photo by Kris De Decker.

Kozimo also made four supporting legs that are almost two meters long. I can use them to erect a tent around the bed, and cover the structure with modern tent materials, wool blankets, or a mosquito net. The large poles can also dry laundry. Furthermore, I could use the supporting legs in various combinations to convert the cart into a podium, expo stand, market stand, or a cinema or presentation screen.

The seat, table, solar panel, sleeping mattress, and longer poles can all be carried on the handcart simultaneously, leaving ample space for other luggage. That means that I could potentially work, live, and travel in the vehicle, turning it into a nomadic home. It fits somewhere between the tiny house on wheels, the tipi, and the homeless shack. Rents got very expensive in Barcelona, so I may as well give it a try.

Image: The handcart is packed for a longer trip. Photo by Kris De Decker.

Sailing and roller skating the handcart

Finally, Kozimo made a small sail for the handcart to help pull a heavy load in a good wind; the vehicle is sometimes used along the coast. Of course, we got the inspiration from the use of sails on the historical Chinese wheelbarrow. For a longer trip, the sail fits on the cart, so I could use it whenever the opportunity arises.

Images: The handcart with a 1m2 sail. Model: Iris De Decker. Photos by Kris De Decker.

We could increase the speed of the handcart by using a larger sail, and combining it with roller blades, inline skates, or a skateboard. In that case, the cart would pull the driver in good winds. It’s also possible to push the cart while using roller blades, inline skates, or an electric unicycle, without a sail. For now, we did a first small test on flat terrain using inline skates, with very good results. If you would take enough cargo, the kinetic energy of a skate-powered handcart would regularly pull you forward even without a sail.

The higher speeds of these configurations obviously introduce more risk and, most likely, trouble with the police. Higher speeds require ample space, free of pedestrians. That almost always pushes the handcart on the road, between the cars, as most cycle paths are not wide enough. However, it shows that sustainable vehicles could take many different forms if only we would give them the space to flourish. There are more than enough roads suitable for sailing and roller-skating handcarts; we need to empty them of cars and vans.

Images: Julia Steketee drives the handcart on online skates. Photos by Kris De Decker.

Handcart design and construction: Kozimo, Guilhem Senges.
Photos: Kris De Decker, Linda Osusky, Guillaume Lion.
Special thanks to: AkashaHub Barcelona, Carmen Tanaka, Gaston Quispe Castros, Linda Osusky, Guillaume Lion, Rocío Sánchez, Iris De Decker, Lili-Roos Noeyens, Julia Steketee, Tim Rudolph, Guilherme Maglio, Selcen Küçüküstel.
Marie Verdeil and Roel Roscam Abbing contributed to the selection of images.

Bulliet, Richard W. The wheel: inventions and reinventions. Columbia University Press, 2016. ↩︎ ↩︎
How to downsize a transport network: The Chinese wheelbarrow, Kris De Decker, Low-tech Magazine, 2011. https://solar.lowtechmagazine.com/2011/12/how-to-downsize-a-transport-network-the-chinese-wheelbarrow/ ↩︎
You could build a handcart with stronger wheels, either heavy-duty wheelchair wheels (available up to 350 kg) or cargo-bike wheels. However, stronger wheels are likely wider, which increases rolling resistance. It would also become more difficult to push these heavier loads up a steep incline. ↩︎
How to get your apartment off-the-grid, Kris De Decker, Low-tech Magazine, 2016. https://solar.lowtechmagazine.com/2016/05/how-to-get-your-apartment-off-the-grid/ ↩︎
How to build a practical household bike generator, Kris De Decker & Marie Verdeil, Low-tech Magazine, 2022. https://solar.lowtechmagazine.com/2022/03/how-to-build-a-practical-household-bike-generator/ ↩︎

Low-tech Magazine: The Uncompressed Book Series

Mon, 30 Mar 2026 00:00:00 +0000

Image: The redesigned and revised chronological book edition. Photo: Marie Verdeil.

Between 2019 and 2021, Low-tech Magazine published three books containing selections of articles from the website, spanning 14 years (2007-2021). In 2024, we launched the “compressed edition”, which squeezes the article catalog of the three-volume book series into just one book of 620 pages.

We did this by switching to a smaller font size, downsizing most images, and opting for a two-column layout. I rewrote some articles, especially older ones, resulting not only in fewer pages but also in better articles.

This revised edition of the original, “uncompressed” series is based on the edits made for the compressed edition. However, we increased the font and image sizes and returned to a one-column layout for improved reading comfort.

The book design is a collaborative effort by Laia Comellas, Marie Verdeil, and Johanna Gratzer. Marie Verdeil made the covers, Vaiva Vinskaitė did the typesetting.

Image: The redesigned and revised chronological book edition. Photo: Marie Verdeil.

The books are available in paperback and hardcover:

Paperbacks:

Hardcovers:

Volume IV (2022-2026)

We’re also working on the final edits for Volume IV (2022-2026), expected to launch in May.

Patrons have free access to all ebooks, and early access to print books at a reduced price. They also receive exclusive content, which includes previews of new building projects and behind-the-scenes news.

Our books are also available as epubs. However, the chronological series is still based on the original book edition. We temporary lowered their price and will launch the new versions in a couple of months.

Winter is Coming: Build a Solar Powered Foot Stove

Sun, 16 Nov 2025 00:00:00 +0000

Image: The electric foot stove that we build in this manual. Photo by Marie Verdeil.

We built an electric cube heater, powered by a 100-watt solar PV panel. During the day, the solar panel slowly heats the cube, which radiates heat to its surroundings. Due to its high thermal mass, the object continues to radiate heat for hours after sunset.

Electric Foot Stove

The heat cube can serve multiple purposes. You can use it as a modern variant of a preindustrial foot stove. Put your feet on the cube and throw a blanket over your lap to trap the heat.

Historically, foot stoves contained glowing sintels from the fireplace, but an electric version is safer and healthier. There is no risk for carbon monoxide poisoning or fire. The heat cube contains no flammable materials.

Image: A nineteenth century foot stove. Source: Museum Rotterdam (CC BY-SA 3.0).

You can also put the cube under a table that has a blanket on top, and that is another method to build an electrically heated table. The heat cube can also quickly dry a pair of socks or keep a prepared dish warm in the kitchen or on the table.

Rather than storing electricity from a solar panel in a battery to operate an electric heater at night, the solar panel stores heat in the thermal mass of the heat cube itself. That’s cheaper and more sustainable, because batteries account for 70-90% of the money and energy invested in an off-grid solar PV system.

Heat can be stored for even later in the night by covering the cube with one or more wool blankets.

Image: The heat cube used as a hand and foot warmer. Photo by Marie Verdeil.

Bricks, Mortar, and Tiles

We created the heat cube using inexpensive and simple materials: bricks, mortar, and tiles. The solar panel supplies power to an electric resistance heater, which we made ourselves and which we laid between several layers of bricks. The electric resistance heater connects directly to the solar panel, without a solar charge controller or voltage regulator in between. If you add more solar panels, the heat cube also works in cloudy weather.

Electric Tile Stove

Our heat cube is relatively small (20x20x25cm), but this manual can serve to build a much larger version, which could take the form of an electric tile stove, which could include a heated bench or sleeping platform.

Tile stoves date back to the Middle Ages and accumulate heat from a biomass fire within a stone or brick mass. They are fired only once or twice per day and continue to radiate heat for approximately 12 to 24 hours. However, a tile stove can also work electrically. In that case, there is no need to add a labyrinth of smoke channels that delays the release of heat through the chimney; instead, only layers of bricks with electric heating elements in between are required. Neither do you need a chimney.

Image: A 1920 tile stove in the "Tautes Heim". Source: www.tautshome.com (CC BY 3.0).

Tile stoves are very heavy, and powering them electrically doesn’t make that any better. Once built, they remain in place. Even our small cube heater is not precisely a portable device: it weighs 26 kg. If you want to move it around, it’s a good idea to put it on a wooden board with wheels mounted underneath. Make sure it can’t slide down a slope.

Solar Oven vs. Foot Stove

This solar-powered cube heater forms part of a larger collection of devices that we built, including a solar powered oven and a solar powered coffee maker. They are all based on direct solar power and heat storage rather than electric energy storage.

All these devices are inspired by tile stoves. However, while the solar oven and coffee maker are designed to keep the heat inside, the cube heater is designed to radiate heat outwards. Therefore, it is the only appliance that has no thermal insulation. That also makes it easier, quicker, and cheaper to build than the others.

Thermostat

The heat cube we built works without a thermostat. Because it has no thermal insulation, there is little danger of overheating and damage to the electric resistance circuit. It’s the room that gets warmer: the cube continues to radiate heat into its environment and maintains a steady temperature. Furthermore, the sun goes down every evening, cutting off the power supply.

However, overheating could occur when you charge the heater with one or more blankets on top, effectively adding insulation, or when you operate it on grid power using an AC/DC converter. To avoid this, you can add a thermostat, which turns off the power source when the surface temperature exceeds a preset limit.

A thermostat can also be helpful when the heat cube surface becomes too hot to touch with bare skin. However, you can also wrap a blanket around it or make a fitting cover, similar to the ones used for hot water bottles. Installing an on/off button provides you with a manually operated thermostat.

What You Need

Six bricks. We used refractory bricks (also known as fire bricks), which are used in high-temperature environments. Refractory bricks are made of silica and store thermal energy very well. However, regular bricks work as well, because they withstand temperatures much higher than those reached in the cube heater. Just make sure the bricks have a 1:2 size ratio, allowing you to create a pile with alternating brick layers.
Mortar. We used regular construction mortar, which can withstand temperatures up to 300°C. Refractory cement combined with sand and water could also work. However, it’s not a requirement because the heater doesn’t reach a temperature of 300°C.
Electric resistance heating element. We made a 100-watt electric resistance heater, which we fixed in the mortar between the bricks. It’s made from nichrome wire and heat-resistant electric cables. See our separate manual.
Tiles. We used ceramic tiles to cover the sides and the top of the cube, and a thicker floor tile at the base. The tiles radiate heat, waterproof the structure, and help to keep it together.
Adhesive mortar. To paste the tiles to the bricks.
A fuse. You add this in the positive wire between the solar panel and the heat cube. Its Amps rating should be slightly higher than that of the heating element. Read more about fuses.
A thermostat (optional). In contrast to the other devices in this collection, the heat cube does not have a thermal switch and thermal fuse. You could add a thermostat to regulate the temperature of the heat cube (see our manual on building an electrically heated table).
An on/off switch (optional). Add this when you don’t have a thermostat.

Image: Step by step instructions to build the heat cube. Illustration by Marie Verdeil.

Building steps

Cut a large and thick floor tile into a square. Its dimensions should be bigger than two bricks lying side by side. We have more information about cutting tiles in the solar oven manual.
Prepare the heat-resistant circuit of 100W. Since we have three layers of bricks, we prepare two separate strands of nichrome wire to evenly spread the heat. One strand goes between the first and second layers of bricks, and the other between the second and third layers. Solder both strands to heat-resistant electric cables. Next, connect these heat-resistant electric cables in parallel. To decide the length and the thickness of the nichrome wire, and other building steps, consult our separate manual.
Prepare some construction mortar following the package instructions. Apply some mortar to the bottom tile and place your first brick on top of it. Add some mortar on the inner side of the second brick before pressing it next to the first brick.
Add a generous amount of mortar on top of this first level and place the first part of the resistance circuit, ensuring the nichrome wires are spread evenly, don’t cross, and remain in the center. Take care that the nichrome wire doesn’t come closer than 5 cm to the sides of the cube, otherwise the surface becomes too hot.
Cover with more mortar and layer a second level of two bricks, perpendicular to the first one.
Place some mortar on top of the second level before laying down the second part of the circuit. Make sure the ends of both circuits are on the same side of the cube and that the heat-resistant cable ends extend at least 5 cm beyond the cube. We will connect them in parallel later.
Place the last layer of bricks, perpendicular to the second level. Use the leftover mortar to fill the holes on the edges of the bricks.
Wait 24 hours for the mortar to cure.
Solder the two separate circuits together in parallel, ensuring there are a few centimeters of space left to extend the circuit with regular cables later.
Prepare some adhesive mortar and cut the tiles for the five sides of the heating cube (except the bottom).
Drill two holes for the cables through the tile on the side where they stick out.
Apply generous amounts of adhesive mortar on all sides and cover the surface. Let it dry according to the mixing instructions.
Once dry, apply grout in between the tiles’ edges.
Connect regular electric cables to each strand to create a power supply cable. We made it 1m long. Optionally add connectors at the end of each cable. The simple resistance circuit has no polarity.

Image: Six bricks form the main mass of the heat cube. Photo by Marie Verdeil.

Image: All bricks are fixed to each other with a mortar layer that also has the electric resistance heating elements inside. Photo by Marie Verdeil.

Image on the left: Tiling the heat cube. All tiles are provisionally taped around the bricks. Image on the right: Grouting the cube. Two holes in the side made to let the cables pass through. Photos by Marie Verdeil.

Credits:

Concept: Kris De Decker
Design: Marie Verdeil
Construction and documentation: Marie Verdeil, with assistance from Hugo Lopez.