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Too Much Combustion, Too Little Fire

The fire – which we have used in our homes for over 400,000 years – remains the most versatile and sustainable household technology that humanity has ever known.

image

Illustration: Diego Marmolejo.

The fire – which we have used in our homes for over 400,000 years – remains the most versatile and sustainable household technology that humanity has ever known. The fire alone provided what we now get through a combination of modern appliances such as the oven and cooking hob, heating system, lights, refrigerator, freezer, hot water boiler, tumble dryer, and television. Unlike these newer technologies, the fire had no need for a central infrastructure to make it work, and it could be built locally from readily available materials.

From Open Hearth to Power Plant

The habitual use of fire dates back at least 300,000 to 400,000 years. 12 Until the twentieth century, the biomass-fuelled fire was the only energy using “appliance” in the household – whether people were living in a cave, a temporary hut, or a permanent building. The earliest shelters were often erected with the express purpose of keeping fire alive, protecting it from wind and rain.

For most of history, the fire appeared in the form of an open hearth, which was built on an earthen floor in the middle of a shelter. The smoke of the fire escaped through a hole in the roof. Beginning in the fourteenth century in Europe, the open hearth was gradually replaced by a fireplace connected to a chimney, most often built against a wall. In colder regions (such as Scandinavia), people built more energy efficient tile stoves, while in milder climates (such as those around the Mediterranean), people continued to use braziers – portable metal baskets in which charcoal was burnt. In the 18th and 19th centuries, fireplaces were starting to be replaced by metal stoves.

The fire remained central in the household until the 20th century, when it was replaced by a wide range of appliances, plugged into central infrastructures. Today, in industrial societies, even metal stoves have become rare in households. Open burning has been all but banned, especially in cities. New buildings no longer have fireplaces, chimneys, or a hole in the roof.

The fire remained central in the household until the 20th century, when it was replaced by a wide range of appliances, plugged into central infrastructures.

“Paradoxically”, writes Luis Fernández-Galiano in Fire and Memory: On Architecture and Energy, “the dwellings that began as places to promote the fire, today shun open burning”. 3 In Fire: A Brief History, Stephen J. Pyne observes that: “Urban residents can pass years without seeing a fire. It appears mostly by accident or arson, and almost always as a danger”. 4

However, the fire has far from disappeared. Thousands of individual fires in households have been replaced by a few giant fires in central power plants. And the fire also burns elsewhere. “In our economy of abundance”, writes Stephen J. Pyne, “fire is at the heart of the magic – in factories, automobiles, homes and power plants… Modern cities remain fire-driven ecosystems… Shut down combustion and you shut down the city. But open flame itself has vanished. Like a black hole in space, fire has shaped everything around it without itself being visible.”

Industrialisation has only altered, not abolished burning. Most importantly, fire started using another energy source: fossil fuels instead of biomass. Until the twentieth century, almost all human-made fires were the product of renewable energy sources: wood, grass, dung – peat and some early uses of coal being the exceptions. Today in industrial societies, almost all fire “at the heart of the magic” burns on gas, coal or oil.

Fire vs. Electricity

Globally, a few billion people still live in households built around an old-fashioned fire, often in the form of an open hearth. Some people in the Western world consider this a backward and primitive practice that needs to be abolished – even though it is based on the use of renewable energy sources.

For example, in 2011, the UN and the World Bank launched the Sustainable Energy for All initiative, aiming to “ensure universal access to modern energy services” by 2030. 5 The concept of “modern energy services” is vague, but it essentially refers to the use of electricity and gas – and thus, in practice, the use of fossil fuels.

“Urbanites see fire as a technology for which other, more advanced technologies can substitute”

Initiatives like this imply that “modern energy services” are “better” than the traditional open hearth or fireplace. “Urbanites see fire as a technology for which other, more advanced technologies can substitute”, writes Stephen J. Pyne. “If fire is a device, they want an improved flame- and smoke-free upgrade”.

Examples of such flame- and smoke-free upgrades are today’s solar PV panels and wind turbines, which are supposed to end our dependence on fossil fuelled fires to produce “modern energy services”. However, how do open hearths and “modern energy services” – including those based on renewable energy sources – actually compare in terms of efficiency, sustainability, health and safety? What are we really saying when we argue that electricity or gas are “better” than a traditional fire?

The Versatility of a Fire

One reason why people in industrial societies regard open fire as inefficient and unsustainable is because they simply don’t know how their ancestors actually used it. If these days a fire is considered to be inefficient, it’s because we only measure the efficiency of one of its functions, usually space heating. However, our ancestors did not only use the fire to warm themselves. They also used it for cooking, illumination, food preservation, hot water production, clothes drying, and protection from predators and insects, among other things.

image

Illustration: Diego Marmolejo.

Fire is extremely versatile: it’s hard to say which of its functions were most valued by our ancestors. Therefore, if we measure the energy use of a household fire and compare it to modern technology, we should not compare it to the energy use of a heating system or a cooking stove alone, but to the energy use of the entire household.

Cooking With Fire

As a cooking device alone, the fire can accommodate a wide variety of cooking methods and replace a surprisingly large number of modern kitchen appliances. The fire not only functioned as a cooking stove, but also as an oven. For roasting and grilling, food was held on a turning spit and cooked by direct exposure to the fire. Baking happened in a clay container (a “Dutch oven”) which was put in the ashes of the fire. Alternatively, a separate bake oven was built into the jamb or the rear of the fireplace, or as a freestanding structure outside the house. Boiling and frying happened in a pot that was hanging above the fire. 67

The functions of many smaller electrical kitchen appliances were also enabled by the fire. For example, you may think that people started eating toast when the electric toaster appeared in the twentieth century, but before that time they simply held a “toasting fork” into the fire. Likewise, quickly preparing warm drinks did not begin with the invention of the electric immersion heater: earlier on, people immersed a red-hot iron tool in a cup, producing hot beverages in a matter of seconds. 8

As a cooking device alone, the fire can accommodate a wide variety of cooking methods and replace a surprisingly large number of modern kitchen appliances.

The fire also substituted for today’s refrigerator and freezer. In The Food Axis: Cooking, eating, and the architecture of American houses, Elizabeth Collins Cromley describes how meat and fish were suspended for several weeks in the smoke of a fire to preserve them for longer. 6 At the simplest level, our ancestors hung their cuts of meat or fish in the kitchen chimney or – if there was no chimney – high above the hearth, suspended from the ceiling. Smoking fish and meat could also happen in a chimney smoke chamber, which was either an adjunct to the kitchen fireplace, or a chamber built off the chimney in the basement or attic. The smokehouse could also be a separate building.

Several other food preservation methods were dependent on fire. Fruits, vegetables and herbs were dried by fire if the local climate wasn’t sunny enough. Sugaring fruits and making butter and cheese all depended on heat from a fire. Salt, essential for food preservation, was kept in a box hung against the fireplace to keep it dry. 6

Distributing Heat and Light

A fire not only produces heat and smoke – it also produces light. As a light source, fire was just as versatile as electric lighting is today. The light of a fire resided not only in the hearth or the fireplace, but also in torches, rushlights, and later candles and oil lamps. 910 Heat from a fire could also be spread all over the household. Although the kitchen was usually the only space in the house that was heated, embers from the fire could be put into portable heating devices, such as foot stoves and bed warmers. 11

The fire was also used to heat water for cleaning and washing, a practice that continued when cast-iron wood-stoves appeared – many of these had hot water tanks. Furthermore, the fire took care of drying clothes, substituting for today’s tumble dryer. And people didn’t just start ironing their clothes when the electric iron came along. Since the middle ages, our ancestors used plain metal irons that were heated by a fire or on a stove, or a “box iron”, which held glowing charcoal inside – some of these had a small chimney to keep smokey smells away from the clothes. 12

People didn’t just start ironing their clothes when the electric iron came along. Since the middle ages, our ancestors used plain metal irons that were heated by a fire or on a stove.

There was also the function of the fire as a focal point of communication and socialisation. For thousands of years, the hearth was the “ancient focus of conversation and the crackling soul of the house”. 3 Televisions and mobile phones have taken over these roles, although it is doubtful whether they hold the same appeal for people as a fire does. A host of electronic consumer products that imitate the effects of a fire – electric candles and fireplaces, led-bulbs with flickering flame effects, video’s of crackling fires – seem to indicate that humans miss open fire.

Sustainability and Efficiency

In a household built around a fire, the making of hot beverages and toast, the drying of clothes, or the illumination of the space does not raise the energy use of the fire: it simply makes more efficient use of the fire that is already there for other purposes – like space heating. To achieve the same result today, we have to turn on a several appliances, and all of them require extra energy use: the heating system, the immersion heater, the electric toaster, the tumble dryer, and the lights.

Furthermore, we should also take into account the mining and the energy use required to replace one fire with dozens of factory-made appliances, which all need to be distributed to individual consumers. Finally, we should take into account the energy and materials that are required to build and maintain the infrastructures that these appliances depend on to operate, like the power grid, gas infrastructure, or the cold chain. In contrast, an open hearth can be built locally with readily available materials, and it operates independently of centralised infrastructures.

image

Illustration: Diego Marmolejo.

Today’s renewable power plants, such as solar PV panels or wind turbines, don’t properly address the energy question: they also need to be manufactured, transported, maintained and discarded of, and they imply that we can keep designing, producing and discarding an increasing range of electric household appliances in order to satisfy our needs. Neither would biomass electricity make this system sustainable: although it eliminates the use of fossil fuels, a great deal of energy is lost in the process of converting biomass to electricity, and we still need factories to manufacture the electric appliances and the infrastructures.

Energy Use Compared: Ancient vs. Modern Households

If we look at the energy use in European households today, we see that on average 64% of all energy goes to space heating, 15% to water heating, 14% to lights and appliances, 5% to cooking and 1% to other services (including cooling). 13 Most of these services can be supplied by fire. So, how does the energy use of a traditional household with open hearth compare to the energy use of a modern household built around appliances and infrastructures?

Obviously, the energy use of modern houses is better documented than that of buildings and shelters from times gone by. However, there is research documenting the energy use of households that still rely on a traditional fire.

If we measure the energy use of a household fire and compare it to modern technology, we should compare it to the energy use of the entire household.

A 2002 investigation of firewood consumption in traditional houses in Nepal measures the annual firewood consumption per household to be between 6 and 33 m3, which corresponds to between 35 and 165 Gigajoule (GJ) of energy. 141516 This seems quite a lot in comparison to the total energy use in contemporary households, which is around 75 GJ per year in Germany and around 105 GJ in Canada.

However, the average Nepalese household participating in the research consisted of 5 to 12 people, while households in modern societies have shrunk to little more than two people. In the Nepalese households under study, energy use was between 2 and 33 GJ per capita, while another, more recent research paper on firewood consumption for heating, cooking and lighting in Nepal calculates a per capita use of roughly 2.5 to 10 GJ of energy per person per year. 1718 In comparison, total household energy consumption per capita is around 30 to 40 GJ in countries like the Netherlands, Germany and Canada.

10 Billion People Around the Hearth

Even without taking into account the extra resources needed to build the appliances and the infrastructures, energy use in the pre-industrial household seems to have been significantly lower than it is today. In fact, a quick calculation reveals that – at least in theory – 10 billion people using an open hearth as their only energy source would be a perfectly sustainable practice.

Assuming an average firewood consumption of 6 m3 per capita, we would need 60 billion cubic metres of wood annually. One cubic metre of wood requires an annual yield of 0.2 ha of coppice, so we need 12 billion ha or 120 million square kilometers of forest if we want to avoid deforestation. That’s three times as much as we have today, and about 80% of the total land area of our planet (150 million square kilometers).

Because we don’t need extra space for factories and roads to make and distribute consumer goods, we actually could go back to the open hearth without destroying our environment. The same cannot be said of 10 billion people going forward using fossil fuels and modern infrastructures.

Health vs. Sustainability

If not for their sustainability or efficiency, then why do we consider “modern energy services” superior to a traditional fire? The suppression of open fire in modern cities is supported by two extra arguments: fire is unhealthy (it produces air pollution), and it is dangerous (it carries the risk of an uncontrollable fire). These risks are real, but how does the fire compare to “modern energy services” in terms of health and safety?

There is no doubt that the replacement of the household fire by modern infrastructures has advanced air quality, health and safety in cities. However, this may only be a temporary gain: modern infrastructures are at least as hazardous to safety and health because of their dependence on fossil fuels.

How does the fire compare to “modern energy services” in terms of health and safety?

For example, the heat waves and forest fires which are ravaging Australia while I write this, are killing people and destroying properties, and they are producing thick smoke that continues to blanket some of the largest cities. These fires are not caused by people using open hearths. These fires are the consequence of climate change, which is mainly caused by people’s use of industrial infrastructures – powered by fossil fuels.

The heavy dependence on central infrastructures for so many vital needs is another health and safety risk: cut the power supply to a large city and almost everything stops working — including the sewer network, the food storage, and the burglar alarms.

Our troubled view of the old-fashioned fire is partly rooted in the conflation of two distinct concepts: “health” and “sustainability”. Indeed, something can be healthy, safe and sustainable at the same time, like walking – lest there is no sidewalk. But something can also be healthy and safe but not very sustainable (like a refrigerator, because it depends on an energy-intensive cold chain), and something can be sustainable but not very healthy or safe (like a smokeroom for meat and fish in the basement).

Health and longevity are things that we, as individuals, “need”, want, desire, or feel entitled to. Just like we feel entitled to certain levels of comfort, convenience, speed or cleanliness. On the other hand, defining sustainability requires us to question what levels of human comfort, convenience, cleanliness, speed, safety and health our environment can support before it collapses. We can choose safety and health over sustainability when they are in conflict with each other, but only at the expense of the safety and health of younger and future generations.

Kris De Decker

Comments

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SRH

Whilst I have recently become convinced that civilisation was possibly humanity’s worst mistake, one which looks set to kill us all eventually, there are some problems with this article.

Telling us that the wildfires which are causing many problems in Australia - and they are certainly a serious threat to life - are more damaging to humans than the use of controlled domestic fires does not seem to have good evidence.

But with fire also came the first anthropogenic pollution, evidenced by the soot still found in prehistoric caves. Over the past few centuries about half of humanity has been able to afford to transition from traditional biomass fuels (wood, animal dung, crop residues such as rice husks, etc.) to fossil fuels such as kerosene or gas, or to electricity. The remaining half of humanity, almost all in developing countries, continues to use biomass fuels or coal, often in open fires or in inefficient, smoky stoves. Consequently, the United Nations Environment Programme/World Health Organization Global Environment Monitoring System (GEMS) has confirmed that the worst overall air pollution conditions and the largest indoor pollutant concentrations and exposures are found in both rural and urban areas of the developing world…

…Demand for traditional fuel also places significant pressure on local forests and woodlands, contributing to deforestation, soil erosion and desertification. Frequently, the need for wood is so great that reforestation attempts of badly degraded regions prove impossible because even young trees are rapidly harvested for cooking fuelwood or charcoal production.” https://lists.bioenergylists.org/stovesdoc/Environment/staton.pdf

Stoves and open fires are the primary means of cooking and heating for nearly three billion people. In India, some 400,000 people die each year from the toxic fumes. In Africa, 500,000 children under the age of five die from pneumonia attributable to indoor air pollution, according to the WHO. And in Afghanistan, smoke from cooking and heating fires killed 20 times as many people in 2010 as did the ongoing conflict. Dr Nigel Bruce, consultant at WHO, said: “The problem is caused by the inefficiency of traditional open fires and stoves resulting in very incomplete combustion of wood, dung and other solid fuels that a majority of people in developing countries rely on for their everyday cooking needs.” https://www.independent.co.uk/life-style/health-and-families/health-news/home-fires-the-worlds-most-lethal-pollution-2192000.html

This does not seem consonant with the author’s back-of-an-envelope calculation of the amount of land needed. Sorry, but this does not appear to be a realistic, healthy, sustainable or safe idea.

Graham Ford

Concerning your proposal of burning 6 cubic metres of wood per capita. That is around 3 tonnes or 45 GJ per person annually.

This seems rather on the high side, especially when some Nepalese households were managing with 6 cubic metres per HOUSEHOLD.

Also, some plants produce biomass in great abundance - Miscanthus and similar grasses will produce 25 tonnes per hectare annually of dry matter in many parts of the world, so 3 tonnes per capita would only require 1200 sq m of land per capita, a growing area for a planet of 10 billion people of only 12 million square kilometers, 10% of what you were considering.

Improve the efficiency of the processes (self-heating houses, efficient stoves, TEG generators for lighting, for example) and probably 10% of this fuel use is all that would be required.

kris de decker

@ SRH

Telling us that the wildfires which are causing many problems in Australia - and they are certainly a serious threat to life - are more damaging to humans than the use of controlled domestic fires does not seem to have good evidence.”

The Australian wildfires are just one example. And there will be more examples each year. We ain’t seen nothing yet.

Kostas

Would you consider writing an article on compost based heating systems?

Although some systems depend on industrial wood chippers, these wood chippers could be powered by biogas produced inside the compost pile (see Jean Pain’s work: https://www.dropbox.com/sh/7j32pgllmomdfew/AADo5-559B4lJyf9EFWqM8FRa?dl=0&preview=Another+Kind+of+Garden.pdf ).

A low tech wood chipper would also be welcome.

Assuming the pile is made for compost, this form of energy could be considered as carbon negative that also contributes to the regeneration of stripped-from-fertility soils.

Some more sources that may help for such an article are: https://www.amazon.com/Compost-Powered-Water-Heater-greenhouse-buildings/dp/1581571941

https://www.tandfonline.com/doi/pdf/10.1080/1065657X.2016.1233082?needAccess=true

J Kovatch

I doubt the calculation of 80% of the earth surface being needed for wood production. The paper industry has perfected the hybrid poplar production and it is surely more efficient than the calculations allow. Last figures I remember are 2 acres will sustain a homestead at a 10 year harvest cycle, or 0.2 acres per year used. I think the big problem would be water for the trees, not the space required.

Julien

Thank you for this reflexion on the firewood topic, however there is a huge contradiction!

so we need 12 billion ha or 120 million square kilometers of forest if we want to avoid deforestation. That’s three times as much as we have today, and about 80% of the total land area of our planet (150 million square kilometers). Because we don’t need extra space for factories and roads to make and distribute consumer goods, we actually could go back to the open hearth without destroying our environment.”

How can you conclude this, when we would need 3 times more forest area?? & i guess this doesn’t even account for the land required for food… What this says is that if we work with the existing area of forests, we might only make it for one third… 3.33 Billion people.

…or did i get this wrong ? how ?

Kostas

@ SRH

Have you looked at microgasification? It essentially eliminates indoor air pollution from cooking and the byproduct(biochar) can actually be used in reforestation, not deforestation. Posted by: Kostas | December 31, 2019 at 12:25 AM

kervennic

You do not need 6 cubic meter. We use around 10 max here for 3 people and our house is way too big for us. With good insulation, large household and intelligent management, my guess is that you would use much less.

It is also not true that fire is very polluting. Most people do not know how to light a fire and go on burning wood at low temperature and polute. They are usually buying wood cut in large pieces that burn inefficiently and are too lazy to spend some time collecting small firewood to get an initial high temperature. If you look at old peasant in cold countries, they spend a lot of time splitting wood in small pieces to get a good fire going on (and fast). They also use extra dry wood and the more you split in advance, the drier it gets.

Even for an open fire, I am spliting all 50 cm long logs in two or three thin piece and put them in a pyramid shape to get a “torching” firewood. The base of the log touching hot amber, turns into gaz (fume) and this smoke trapped between the log and the wall burns at the top of the log. Besides, when you put a new log, water is escaping at the top (you hear a pssshit and see bubbles), whereas in the horizontal mode, it is mixing with combustion gaz and lowers efficiency.

I get a real powerfull torch for hours and I guess i am well above the 15 percent “theoritical” efficiency of open fire, because it actually get pretty warm in the room, even if it is zero outside. I guessed people found a lot of tricks, playing with fire on a daily base and would probably not all live in toxic fumes.

Chimney design is also crucial. Here they do not let smoke comin into the room if you burn like I do.

Joshua Spodek

The section “Energy Use Compared: Ancient vs. Modern Households” made me think of my food power consumption. It was December and I don’t heat my apartment so it’s chilly.

Yet my refrigerator was on. As I started to wonder if I could get by without it, at least during the winter, when the apartment is cool anyway and my food is less perishable — more root vegetables, cabbage, etc — I figured the best way to find out was to try. Nothing would kill me and I’d find the problems to solve best by exposing and facing them.

So I unplugged the fridge, ate the perishable things, and will see how long I can go before plugging it back in. Putting things by the window, where it’s cooler, is working so far.

I think Low Tech Magazine started me fermenting things instead of refrigerating … [searches site] … yes, these posts:

https://www.lowtechmagazine.com/2017/02/vietnams-low-tech-fermentation-food-system-takes-advantage-of-decay.html

https://www.notechmagazine.com/2015/07/preserving-food-by-fermentation.html

So I already have a bunch of sauerkraut and vinegar. Let’s see what comes next. I also look forward to my electrical bill.

Arthur

Intresting article! It’s not like heat from electronic stove, other appliances disappear, it stays in the house. If heating system uses termostat than it doesn’t use more energy. At warm period of the year people tend to avoid unnecessary heating. Clothes can be dried as easily with central heating as well from the same fire that was used to create electricity. Biomasas has to be harvested as well - sure it is not as energy intensive as mining copper or cobalt.

It is right on point that we need to stop overusing resources on disposable products, optimize the whole system if we want to live as easy as we are able to do now for many years to come.

Simon Derauw

Dear Kris,

I quite not understand when you considerate sustainable to have about 80% of the total land area of our planet reforested in order to supply fire combustion for 10 billion people. Obviously, we are far from having that space available considering the land use of 10 billion people.

Kind regards, Simon

Bruce Teakle

Thanks Kris for another excellent article.

I live in Australia and a lot of my time is spent managing native forest on private land, with a big focus on reducing the impact of wildfire on people’s stuff and on ecological values - both of which are being devastated by our current season of wildfire on top of drought.

Climate change is making bushfires much worse, but this comes on top of 100 - 200 years of white-fella management (or non-management) of our forests. Aboriginal fires - cool and frequent - reduced understorey vegetation and enabled trees to grow old and big.

Thickened understoreys and infrequent fire leads to much hotter fires, killing tall trees, burning down hollow trees and leading to shorter, hotter-burning regeneration.

Stepping back our sick and overcrowded forests to a more Aboriginal structure is complex: often you can’t simply burn it into shape. It takes lots of cutting and fuel disposal to re-structure the forest without incinerating it.

I have a constant struggle working out how to dispose of surplus wood fuel without causing more forest and soil damage. We use wood to cook in our own home, make charcoal for cooking and blacksmithing, make biochar for gardens and orchards and make things out of wood - but this takes a lot of labour and processes relatively tiny amounts of waste wood.

This means that a lot of energy wood could be produced as a by-product of managing forests for ecological values. If it’s burnt in the communities that are in the forest, minimal energy is required for harvesting and transport, and the ash and char waste can be returned to the land that produced the wood.

Will wood produced this way sustain the affluent lifestyles of our wealthy cities? Of course not - could anything?

Pierre

Dear Kris,

Thank you for this article. It would be usefull I think to mention “new” stove designs based on Aprovecho Research Center’s rocket stove. This design manages to produce high energy with much less fuel and almost no smoke thanks to complete combustion. Those stoves are among those promoted by the Clean Coocking Alliance (https://www.cleancookingalliance.org/home/index.html) Well designed rocket stoves work so well that they now epitomize low-tech for me.

Marnix

While I agree with the point made in the article: the under-appreciation and usefulness of a fireplace, using forest fires in Australia as an example of climate change weakens it. Forest fires are a natural occurrence in most of Australia and other dry regions of the world. Many plants have evolved to survive and thrive with fire, so-called pyrophyte plants. Some species like Eucalyptus have deliberately evolved to be flammable, and many species of pine have seeds that only germinate after being exposed to high temperatures. Large scale forest fires neither are a new phenomenon, nor are the recent temperatures any extremer than those measured prior to 1910. Which is the reason for media and researchers not to include older temperature records as it would show no upward trend for Australia, but more of a ‘business as usual’ scenario.

David Veale

Don’t forget the important byproduct of a wood fire — ash! We both heat and cook over wood in our Michigan home, and I also use the ash for fertilizing our orchard and garden (it’s the original “potash”, high in calcium and potassium for sweetening acidic soils), dehairing hides as part of the leather tanning process, and also for creating lye used in soap making. It’s precious stuff — and even with our extensive use (about 6 cords per year), we generate less than 100 gallons of it annually.

kris de decker

@ Marnix (#14)

I read very different things about the reasons not to include temperature recordings from before 1910: https://theconversation.com/factcheck-was-the-1896-heatwave-wiped-from-the-record-33742

David Veale

@Marnix — as a forester I studied wildland fires quite a bit, as well as having fought them. The key here is the fire return interval. Most all forests have a typical interval (in Washington State, USA where I worked, it was 500 years on the wet side of the Cascades, and somewhere between 5-30 years on the dry eastern side of the mountains). If the fire return interval becomes too frequent, forests cannot establish — assuming there’s still enough precipitation (typically 25cm annually, where it doesn’t all evaporate too quickly) for them to establish. I strongly suspect that many Australian forests are seeing a significant increase in fire frequency combined with a drop in average available soil moisture — just as we’re seeing develop in California and many subtropical environments.

Puquio

One point that makes the claims less straight forward: What about flexibility? It is rather rare being in need of all the opportunities an open fire delivers. So the consequence is a huge drop in efficiency by firing up each time you just need a coffee. At the same time you cannot stop one effect from another, so light will always mean heating, if you have overheaten, you need to waste all the energy by getting rid of it somehow. Our ancestors logic, third world economy and your calculation are based on very specific conditions that are just not to be found in our grown-up societies. Conditions are: small-crowded living spaces, constant huge heat loss, cheap broadly available fuel, low purchasing power, small complexity overpowers specialisation, not constricted time windows

kervennic

Interesting article, but the debate is obviously not closed.

I live on the southern slope of Massif central, at 500 m above sea level. It gets reasonably cold in the winter with several nights under -5 degree celsius. I have an open fire in the kitchen (because i have very low income and little time to rebuild the place) and a cast iron stove in one room. Living in the kitchen during december and january is tough. It usually gets under 8 degree and every task becomes painful (for the fingers…). You would not be able to have a sedentary job at this temperature. These houses were build by farmers in the 19th, tough people who worked outside as much as they could…

I usually burn between 10 and 15 “stere” (french measure) of hard wood for both stove and open hearth. It correspond to 7 m3, for four. In the room, with a small stove, we have 18 degree in average (22 in the evening, less in the morning) and my partner does office work at home. The stove is simple but efficient.

However, there are advantages and disadvantages: with experience, i came to be able to make a very warm fire, nearly smoke free, in a matter of minute in an open fire place. Impossible to get the same effect with a stove if you get home wet and shivering after a cold rain.

Ancient people would have found stove inconvenient because, to have a small stove burning nice and warm you need a lot more work on your wood (sawing and splitting), whereas you can burn larger piece in an open fire. If you do not have expensive machines to make the wood fuel, you’ll find it is tough. Noone can tell if those complex machines that usually run together with tractors and thus need petroleum, will be massively available un the long term. I doubt it.

Ancestors were smart. If it is hard to warm a large room with a simple fire, they had a trick: they were building reflecting walls https://www.alternativ.nu/index.php?action=media;sa=media;in=4774 It you sit in between the walls, then it is warm. I started to insulate the ceiling with raw wool for some years, and the temperature have gone up quite a bit.

To make a smoke free fire, I usually try to cover the burning center with wood, so that it radiate back to the center. In this way it gets really hot, with a lot of red amber, and it then burn long dried wood (i split logs)positioned verticaly against the wall. In the end one can put large logs against the hearth (not in the hearth)and get large flames and no smoke.

Craig Wilson

To whomever this may concern…

Regarding the sub section of this article titled: “10 Billion People Around the Hearth”

In my estimation, there is a fundamental miscalculation in the land area available for forests as follows:

You assert that the land available for forestry/ fuel production is “three times as much as we have today, and about 80% of the total land area of our planet (150 million square kilometers).”

However, given that the worlds desserts account for 33%, the tundra and polar areas another 10-12% and alpine/heavily polluted areas a further significant percentage, at best we only would leave around 50% even before we started discounting habitable residences, roads, ports and other vital parts of infrastructure (think water storage distribution and treatment by way of example). I therefore don’t see it as even remotely achievable to produce enough firewood for our current population let alone account for future population growth.


  1. Roebroeks, Wil, and Paola Villa. “On the earliest evidence for habitual use of fire in Europe.”. Proceedings of the National Academy of Sciences 108.13 (2011): 5209-5214. 

  2. Berna, Francesco, et al. “Microstratigraphic evidence of in situ fire in the Acheulean strata of Wonderwerk Cave, Northern Cape province, South Africa.” Proceedings of the National Academy of Sciences 109.20 (2012): E1215-E1220. 

  3. Fernández, Guillén, and Luis Fernández-Galiano. Fire and memory: on architecture and energy. Mit Press, 2000. 

  4. Pyne, Stephen J. Fire: a brief history. University of Washington Press, 2019. 

  5. https://www.seforall.org 

  6. Collins Cromley, Elizabeth. The food axis: cooking, eating, and the architecture of American houses. University of Virginia Press, 2010. 

  7. Unlike today’s gas or electric stoves and ovens, a fire has no buttons to control its temperature. For boiling and simmering, this was solved by hanging the pots on a crane, which could be raised or lowered. In ovens, cooks decided to bake pies or bread first while the oven is the hottest, then, successively as the oven cools down, gingerbread, custards, then grains could be put in to dry. [6] 

  8. Marcoux, Paula. Cooking with fire: From roasting on a spit to baking in a tannur, rediscovered techniques and recipes that capture the flavors of wood-fired cooking. Storey Publishing, 2014. 

  9. Hough, Walter. Fire as an agent in human culture. No. 139. Govt. print. Off., 1926. 

  10. The energy source for these distributed fires were wood, resin, wax, fat, grease or oil. Needs for special concentration and position of the source of illumination stimulated the invention of holders, brackets, and stands. [9] 

  11. Heating people, not spaces: restoring the old way of warming, Kris De Decker, Low-tech Magazine, 2016. 

  12. History of ironing, Old & Interesting, retrieved December 26, 2019. 

  13. Energy consumption and use by households, Eurostat, 2019. 

  14. Rijal, H. B., and H. Yoshida. “Investigation and evaluation of firewood consumption in traditional houses in Nepal.” Proceedings: Indoor Air (2002): 1000-1005. 

  15. The energy content of 1 m3 of wood also depends on the type of wood and how it is stacked. I’ve compared apples to apples when it was possible, but this was not always the case so the result is only a rough estimate. 

  16. The annual firewood usage in 18th century Austria (Carinthia) was limited to 35 m3 per household. Source: Peter, Sieferle Rolf. The subterranean forest. Cambridge: The White Horse Press, 2001. 

  17. Rijal, Hom Bahadur. “Firewood Consumption in Nepal.” Sustainable Houses and Living in the Hot-Humid Climates of Asia. Springer, Singapore, 2018. 335-344. 

  18. The results are 0.5 to 2 m3 of firewoord per person per year, which I have converted to 2.5 to 10 GJ of energy per person per year. 

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