Love and Hate
I have a love-hate relationship with technology. On the one hand, I love technology. Case-in-point: My enthusiasm/addiction for building, tweaking, and troubleshooting computers.Early on (middle-school-era Mark), this curious tinkering had some unfortunate and smelly side-effects, namely, the fireworks-like frying of a few components (fried components give off a very unique smell somewhat reminiscent of burnt French fries). But, more important than the forfeited components were the lessons I learned along the way, lessons like never to put a power supply directly on a metal case, or alternatively that metal is not a semi-conductor, but rather an all-the-time conductor. Truthfully, the inaugural part-fry is an important stepping stone for any would-be computer enthusiast. After all, learning what not to do can be just as important as learning what to do.
Eventually, this budding passion matured into a capable knack for spec-ing and building custom computers. Like a chef carefully tasting each ingredient as he develops a recipe, there’s something strangely satisfying about thoughtfully selecting each component to hit that sweet spot of price-and-performance, putting it together, and then finally watching it all roar to life with the press of a power button. So, I love technology.
I also hate technology. I bemoan the way cell-phones connect us to those far away, and yet disconnect us from those closest to us. Similarly, social media connects us to the world at large while isolating us from the world around. We scroll through our news feeds insulated from genuine human contact. The concrete jungles we have erected separate us from the planet upon which we live and breathe, disconnecting us psychologically as much as a physically from the Earth.
So, I love technology, but I am also wary of viewing it as a panacea-like savior. Don’t get me wrong. There are some amazing high-tech solutions out there, but our 21st century way of life can create the tempting illusion that the best solution is always the most high-tech. Truthfully, some of the most elegant and effective solutions can be deceptively simple, sometimes even ancient.
Wisdom of The Ancients
Just the other-day, I stumbled upon a fascinating piece of ancient heating technology. That this ancient technology can rival, and in some cases even surpass, modern offerings makes it as impressive as it is intriguing. There are as many names for this technology as there are cultures that used it. It is perhaps most commonly known as a “glazed tile oven” or “masonry stove.”If you live in the United States, you’d be forgiven for not hearing about this ancient and amazing technology sooner. While extremely common place in Europe, they were virtually unseen in America until the late 1990s. The reason for this is surprisingly simple.
For much of history, wood-burning was the primary source of heat. In Europe, firewood became a relative scarcity. This created the incentive for more efficient wood-burning appliances to heat buildings. In America, on the other hand, firewood was so overabundant there was relatively little incentive to move past the inefficient fireplace. Thus, while America continued to use inefficient fireplaces, Europe and Asia were pioneering a radically efficient heating technology: the masonry stove.
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| A traditional take on the masonry stove (image courtesy of niftyhomstead.com) |
Get this: The masonry stove can be 80-90 percent efficient. That means 80-90 percent of the heat generated is outputted entirely into the home. Compare this to 10-15 percent efficiency of a traditional fireplace where most of the heat is swept up the chimney. But this is just the beginning. No seriously, hold on to your socks.
The truly revolutionary aspect of the masonry stove is that it heats up people instead of spaces. This may seem borderline blasphemous, but contrary to the forced-air heating systems in most of our homes, it is possible to heat up a person directly rather than heating the entire volume of air around them.
Heated Discussion
Most conventional heating systems work like this. You turn up the thermostat and a furnace heats up air which is then forced into a space until the entire volume of air in that space is at a desirable temperature. This seems like a good idea on the surface, but there are many issues with heating air. For instance, convection: the fact that once heated, air rises to the top of a space even though people are typically at the bottom of a space, the end result being the heat is not where the people are. Not very good. Not very efficient. |
| Convection heating left versus radiant heating right (image courtesy of Dario Camuffo) |
Convectional forced-air heating also has the byproduct of creating a less than desirable indoor air climate. The circulating air caused by convection routinely stirs up and scorches dust, drying out the air. This can be offset by using humidifiers, but these can create perfect breading grounds for dust mites, molds, and other allergens. The end result is that force-air systems create a less healthy indoor climate.
But what if you could avoid these problems and instead of heating the entire volume of air in a space, you could just get right down to heating the person and the objects in that space instead? Well, I’m here to tell you, you can! This is exactly what masonry stove does through a magical form of energy transfer known as “radiant” heat.
A Personal Sun
The concept of “radiant” heat can see a little foreign at first, but radiant heat is something we are actually all very familiar with on an intimate basis…well, if you get out in the sun that is.
A great way to think of radiant heat is when you are outside on a sunny day next to a spot of shade. The air in the shade and the air out of the shade is essentially the same air and essentially the same air temperature; yet, when you step into the shade you feel cool, and when you step into the sun you feel warm. It’s not the air temperature that has caused you to feel warm and comfortable. It’s the radiant heat of the sun.
The masonry stove works similarly to the sun. It emits heat in the form of infrared waves. These infrared waves travel through the air, and more than heating the air itself, the radiant heat warms the people and objects (anything with substantial mass) that it comes into contact with. This means people can still feel warm without heating every single cubic foot of air in a space. Essentially, heating with a masonry stove is like having a personal sun in your home.
So what exactly is a masonry stove, and how on earth does it accomplish this magical form of highly efficient radiation? A great question! Let me ‘splain.
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| Modern masonry stove in a lab, covered in heat sensors (image courtesy of cornishmasonrystoves.com) |
Rock-et Science
While the above science of radiation may seem a little
high-level, for all its efficiencies, the masonry stove is actually deceptively
simple. A masonry stove is essentially a
small fire chamber built directly into an encasing of stone. This may sound mundane on the surface, but
there are three key parts to the masonry stove that make it highly efficient.
First is the fact that stone is used instead of metal. This isn’t some aesthetic decorating
whim. This is imperative. Metal may have the advantage of heating up
quickly, but it also has the disadvantage of cooling down equally rapidly. Thus, for metal to stay warm, it has to be
heated continuously which is less than desirable. Stone on the other hand heats up more
gradually, but once hot, holds onto its heat like a cop to a cup of coffee. Essentially, the stone in the masonry stove serves
as a big old “heat battery.”
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| As you can tell by this cross-section, masonry stoves are A-maze-ing |
Within this stone encasing is a tightly-packed maze through which the heat of the fire travels on its way to the chimney. The maze is important because it creates the time, distance and surface area necessary for almost all of the heat to be soaked up by stone before heading out the chimney. The end result is almost no heat escapes out the chimney.
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| The winding, labyrinth-like air channels of a masonry stove |
Hot Stuff
Lastly, the fire is able to burn at extremely high temperatures,
about two to three times that of a traditional fire place (near 2000F as
opposed to 700F). This has the benefit of not only extracting nearly all of the
heat from the wood, but also creating complete combustion. This means an extremely clean burning fire with
almost no smoke, pollutants, or creosote (the bad stuff that causes chimney
fires). So the hot fire is actually
safer as well as cleaner and more efficient.
It’s also worth noting that even though fire burns extremely
hot, the stones themselves are not scalding.
This means you can touch the fireplace without fear of needing a
skin-graft like with a traditional metal wood stove. In fact, some masonry stove designs will even
include benches or beds built into them for the user to sit on.
So, in sum, what we have here is a hot, clean burning fire
that minimizes pollution and maximizes heat which is then stored in and
radiated from a stone storage “heat battery.” On a practical level, this means
the fire only has to be lit for a very short period of time, anywhere from 30
minutes to two hours, after which heat releases continually from the stone for
the rest of the day. But the stone
doesn’t just release the heat in some namby-pamby fashion. It radiates
heat.
As mentioned earlier, the fact that the heat is primarily radiated as opposed to conducted or convected like modern heating systems is key. The properties of stone allow it to radiate
heat slowly as low-frequency infrared waves.
Rather than heating the air itself, the infrared waves primarily heat
whatever they come into contact with directly (the people and objects in the
room), a much more direct and efficient form of heating.
This high efficiency both from the complete combustion and
radiant heat translates into very meager amounts of firewood. It might sound like poppycock, but between
one and two cords of wood can heat an entire 650 square foot home for a whole
year (source: low-tech magazine)! That's approximately one tree for a whole year of heat. Further developments of the technology allow this compact
modern model offered in Europe (see picture below) can heat up to 1600 square
feet.
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| An example of a modern masonry heater from European company Contura |
Green Speak
Keep in mind that wood is not only typically cheaper than oil or gas, it’s also considerably less polluting to harvest and completely renewable and carbon-neutral if responsibly replanted. So, if you look at the total energy chain from start to finish, harvesting to heating, the masonry stove is even more efficient than a conventional fossil fuel based heating system. The end result is maximal heating and minimal pollution based on an inexpensive and renewable fuel source, all done using technology pioneered in the 1300s. Not bad.
While the technology is ancient in origin, in Europe especially, companies have continued to develop this technology into a competitive alternative to conventional heating. Some of the results are truly impressive. It’s also worth noting though masonry heaters are traditionally fueled by wood, they can be modified to use gas or work in concert with it. They can either supplement or supplant a conventional heating system.
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| A modern masonry heater built into a wall is both aesthetically pleasing and functionally effective |
Finnish-ing Up
There are drawbacks, however. Stone is heavy and expensive and masonry can be challenging to mass manufacture, though it is being done. Thus, the initial upfront cost of a masonry stove may be more than a conventional heating system, but the masonry stove is so efficient, the modern-day Finnish government actually subsidizes the installation of masonry stoves in new homes.
Masonry heaters also benefit from a relatively open floor plan to function optimally. In the same way the sun can’t warm you in the shade, if you can’t see the masonry heater, you can’t fully feel its radiant warmth.
Masonry heaters may not be perfect, but neither are our modern heating solutions, and for being as old as they are in origin, masonry stoves are surprisingly viable. There is wisdom in these old technologies, wisdom worth remembering, and in some cases, wisdom worth reviving. The fact that such an ancient technology can rival and in some ways surpass current heating solutions in terms of high-efficiency, low-pollution, and carbon-neutrality is truly amazing. And that's not poppycock.
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Sources and Further Reading:
Modern masonry stoves currently available in Sweden: http://www.contura.eu/english/
Modern masonry stove company based in England: http://www.cornishmasonrystoves.com/
In-depth article on the history and science of masonry
stoves: http://www.lowtechmagazine.com/2008/12/tile-stoves.html
Basic overview of masonry stoves: http://www.alternativeenergyprimer.com/Masonry-Heaters.html
Basic overview of masonry stoves: https://www.niftyhomestead.com/blog/masonry-heater/
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