Less waste, less energy: better ways to heat places in a temperate climate

— Anh NGUYEN

One of the first things that marked my eyes when I first came to live in France is the heaters. We don’t have that in Vietnam (this means even if the temperature is 5 to 10°C in the North of Vietnam during 3 winter months, the only thing you could do is to wear more clothes). And here in Europe, it takes up a big part of your energy budget. 

Modern underfloor heating

My host in Le Finistère, Brittany, France pays around 600 euros per month during winter months to heat her enormous renovated farmhouse. This includes the price for electrical underfloor heating for two grand salon areas and electrical heaters in three bedrooms.

The underfloor heating technique has dated back to the Neoglacial and Neolithic periods – for example, Ondol in Korean traditional houses or Hypocaust in Roman times. This system, which mainly requires mud and stones as the main materials, can maintain heat for an extended period – even when inhabitants extinguished the fire during sleep time, the heated place can stay warm until the morning. (On a personal note: this practice is just so COOL, so tempting…But more on that later.)

Illustration of Ondol floor heating in a traditional house in Korea
How an Ondol works. Source
Illustration Ondol floor heating in a traditional house in Korea with a person
Ondol means “warm hollows”. Sounds like a wholesome Kdrama. Source 

Electrical underfloor heating in our modern days makes little sense now in my opinion – out of my experience at the enormous farmhouse in Brittany during winter months (it’s extremely expensive, while you are still cold and need to wear a lot of clothes to warm yourself). Maybe the problem lies in the fact that the house was enormous and it’s made of stone so it’s going to take a LOT of energy to heat the whole thing, this is just not an efficient, the most suitable way of heating for this type of structure. 

It is also difficult to find articles on the internet listing the disadvantages and advantages of modern underfloor heating, without a commercial touch to it (most of these articles are written by providers of this practice).

But if you look at this Wikipedia page that illustrates the installation of modern-day underfloor heating, you might think “hell, that looks like a real nuisance to install this stuff“. Again, as long as we have to use electricity to heat our place, and as long as we are still dependent on fossil fuels or nuclear power to produce our electricity, we are still generating so much waste.

Fireplace & wood burning stove

In this farmhouse, we also have a fireplace. As much as I love the open fire and its therapeutic effect of it, it is an extremely inefficient way to heat places. According to this source, only 30% of the energy produced in open fire transfers as heat in the room, the remaining 70% of the heat is lost up the chimney. Also, despite my adoration towards the smell of open fire, in a long run, it can cause internal air pollution problems.

In December, I stayed with my family in an (almost) tiny house in Morvan (Burgundy, center of France, one of the coldest regions in winter in France). They use a system of wood-burning stove and hot “air conditioner” to warm this 2-floor house. The wood-burning stove is built with a big chimney that transfers heat from the stove to the 2nd floor with 2 bedrooms. And as hot air always moves upwards, the 2nd floor is well heated (sometimes, TOO well heated that we need to open the window even if it’s deep winter). And when you open the stove to put more woods, the smoke goes up as well, so it is a big concern when it comes to air quality.

A side note: on Quora, there is a question asking “If the fireplaces with chimneys are ineffective at heating a home, why were they used for thousands of years?” and the first answer has well addressed the limitation of past vernacular home designs (no insulation, no damp-proof system…), with some examples of houses in West Highland Scotland and Russia.

Heat pump

Back to France, modern day. Another host of mine in Guérande, historical Brittany but far more to the South (less harsh climate), uses a heat pump, which is told to be less energy-intensive than conventional ways of electrical heating. The heating cycle of a heat pump works like that of a refrigerator: taking heat in from the air outside, warming it up further, and pumping this warm air back to heat indoor air. Indoor temperature is constantly kept at 19°C or 21°C adjusted to your liking and your thermal comfort. One thing worth noting is that you should have your windows closed so that the heat pump won’t just keep pumping to reach that predetermined temperature.

Illustration of how heating cycle works to heat a room
The principle of heat pump. Source
A white cat by the window, locked in a pink city house
Sorry cat but you are not going out. Source

Passivhaus

The main principles of Passive house include passive solar gain design (which really just means to minimize the energy requirements in a temperate climate in our case of Europe), superinsulation (also means very very thick walls), advanced window technology, airtightness, space heating…

Model illustration of a passive house standard with isolation by thick walls, floor and roof
The most important aspect to passive house design – the U-value. Source

I didn’t find many resources in English related to this practice of Passive house. There is one Passive house in the Parisien region, I think I should visit them during the winter months to understand the real experience of living in such houses. I’ll update on this later.

Old ways of heating

Lately, I came across this articleRestoring the Old Way of Warming: Heating People, not Places” on Low-Tech Magazine. 

The author highlights the fact that in modern days we are too much focused on convection (heating of air), while overlooking other systems based on conduction (heating through physical touch) and radiation (generated by thermal motion of particles in matter). 

Most modern heating systems are primarily based on the heating of air. This seems an obvious choice, but there are far worthier alternatives.

Kris De Decker – Low-Tech Magazine

I didn’t know it before, but now I find the heating of air – e.g our conventional electrical heaters, is extremely inefficient, not to mention that most of our electricity today is not environmental-friendly sourced and also leaves out so much waste. You heat the air that eventually will go up in the ceiling instead of heating actual people below. Too bad if you’re short like me.

Anyhow, that’s surprisingly dumb. That is a failure of design. 

Illustration of central air heating and local air heating in a big structure like a church
Church heating: Figure 1 The two heating strategies: (a) central heating aims to provide even heat distribution throughout the building while also supplying heat to the building envelope. Most of the heat is accumulated in the upper part of the building (b) local heating aims to produce the best radiant temperature within the occupied area of the church only, with some local increase in air temperature and minimum draughts. The rest of the building remains almost unaffected and preserves or remains close to its historical climate. Source
Illustration of thermal heat transfer in nature with the involvement of the sun, sea and soil
Example of thermal heat transfer through convection – seems like only Nature can do this efficiently, on a much grander scale. Source

On heating through radiation – this confused me at first, but in fact, there is nothing fancy about it. Here are some examples of radiation heat transfer: the heating of the Earth by the Sun, or flames, coals & hot bricks). 

In the article, the author gives some examples of local heating instead of air heating, including local insulation (four-poster beds, folding screens…- as we can see in those palaces such as Versailles or others in Europe), portable heating systems (foot stove or Kotatsu in Japanese or Korsi in Persian) or conductive heating systems (the famous Ondol as mentioned above, or Kang bed-stove in China, or tile stoves/mansory heater in England or in the US).

A sketch of a four-poster bed in a palace in Europe during the Middle Age
Folding screens in those fancy palaces. Source
A sketch of a four-poster bed in a palace in Europe during the Middle Age
Four-poster bed. Source
A red kotatsu in a living room to heat and warm people during winter in Japan
Kotatsu in Edo period – One of my childhood dreams is to try out this Kotatsu and eat ramen. Source
A green tile stove in Alsace France
Tile stove in Alsace, France. Source

Tile stove

I find tile stoves, or oven stoves quite amazing: energy-efficient, healthier than an open fireplace, and greener than modern ways of heating. Yes, greener. In Brittany, France, for centuries, the poorer population used gorse to make fire – this native plant can be found abundantly anywhere in this region, can be burnt dried or humid

The common gorse plant with yellow flowers
If you read French, there’s a wonderful book on the practice of burning gorse for fire in Brittany here. You can email us at waste.failureofdesign@gmail.com and we can borrow you a copy. Source

So instead of generating nuclear waste or using fossil fuels and complex electrical devices for heating, I don’t see any problem with cutting down some branches that will grow every year anyway to make fire. Again, this practice must be applied region by region – based on the types of plants existing natively there. I still don’t know how we can do that with cities such as Paris. (Or, should metropolitan cities like Paris exist at all? More on that in upcoming articles). 

On tile stoves, Low-Tech Magazine did a wonderful job in detailing the pros and cons of this type of heating here in this article. This once-popular system was replaced by European governments in the 18th century, in an attempt to find a greener practice of heating due to the shortage of wood (this resulted in our current systems using coal, gas and oil.) 

A way less eye-catching version of tile stove is rocket mass heater, developed during the 70-80s, whose production is less complex than a traditional tile stove, and also, with cheaper materials.

A DIY cob-style rocket mass heater made in a wooden house
A cob-style rocket mass heater, with a heat exchange mass made with cob. You can also build one with sheet metal like this guide here, though I’m not sure how can you not burn your fingers if you touch it. Source

To push the exercise further, an alternative to all of these systems to heat places is to heat ourselves instead, with heated clothing, even though they still use batteries.


If you to read further on this topic:

Different sources of energy: which one is less bad?

Build our houses the way we build LEGOS?

The absurdity of gardening

5 thoughts on “Less waste, less energy: better ways to heat places in a temperate climate

  1. Keeping windows closed is not a specific problem associated with heat pumps, it’s simply a good practice in order to isolate any heated space – including passive house, from the colder air outside.
    Heat pump is actually one of the best commercialized solution to space heating, they transfer heat efficiently from a cold source to a hot source instead of generating heat by Joule effect or combustion like traditional solutions, thus the lower energy use. A reasonable heat pump on the market may have a coefficient of performance of 5, meaning for 1 kW of heat injected inside the heat pump only consumes around 200 W in electricity, which also means five times less than the consumption of conventional electric radiators.
    For something which vaguely ressembles Passivhaus but more international there is the concept of net-zero energy building.

    Like

    1. Indeed! Thank you very much for the interesting inputs 😉
      When it comes to convection heating (air heating), heat pumps can be one of the most efficient solutions out there. Yet, its environmental impacts depend a lot on the energy sources (coal? gas? nuclear? solar? etc.), and a possible rebound effect (it’s so efficient that we heat the house up to 22°C during winter months).
      I invite you to read our article on Different sources of energy here https://wasteisafailureofdesign.wordpress.com/2021/04/11/different-sources-of-energy-which-one-is-less-bad/, and would love to hear your opinion 🙂
      — Anh

      Like

      1. With France as context, looking at some 2015 stats from INSEE shows that most of French residences use urban gas (39% residences) and electricity (35% ; heat pumps not included in this category) as their main heating energy. Gas is carbon-intensive while heat pumps also consume electricity, but theoretically at least 3-fold less, so I see an interest in transitioning to heat pump when possible (the upcoming RE2020 regulation will also eliminate gas heating de facto for new buildings).
        Rebound effect is possible indeed, but it is desirable to have studies which try to quantify this. If a change in technology, for example, leads to a 66% reduction in energy use with a rebound cancelling the 40% reduced then it will result in a net decrease which is still a welcomed change. The rebound depends on how much is the extra heating to raise the indoor temperature by 1° (which itself depends on building isolation) and how many people do so, and by how much.
        After reading some more, I agree that tile stove has interesting advantages but this can be nuanced.
        By the way collectivization by central heating or district heating can lead to some economies of scale. A good way to do this is with wood (more dense and less humid than gorse), smoke and ash can also be treated more efficiently than for individual stoves, cf. Biomax in Grenoble, but again this is for convective-based systems.

        Your article on energy sources touches on plenty of interesting and complex subjects. Probably I can offer some nuances one day but I’m not sure when.

        Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s