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Natural Building & appropriate technology’s blog 24


Article 24 of Natural Building and Appropriate Tech Internship


And one more big week for us at the Koanga Institute.

So what happened this week?

Guess what? The roof is done! And it really change the aura of the building. So let’s go and begin the walls. For that Big Ben with the advice of Bob and the helps of the team created the perfect mix that we can work with. The Idea is to create a light earth mix with pine needles and some silty clay coming from the bottom of the pond. It has to be quiet aerated. We don’t want thermal mass but insulation. Which means that we just dip the pine needles in the “sludge” for them to be able to stick together but at the same time we don’t want it to be too soggy and heavy. The goal is to have a lot of air gap between the needles.

First, pine needles harvesting! Going in the pine forest and being sure to take only the top layers of the needles. They are the one that have not begin the decomposition process now so their tensile strength is way higher than the rotten one. Logic you would say.


The crew coming back from they hard work.

And then collecting sludge. The dam is empty, the syphoning worked well and now let’s jump into the mud!


Cold mud, up to the knees, nothing better for the skin!

And finally beginning the wall. Figuring out the right ratio of pine needles and sludge and here we go. Handful by handful it is going up.


The very beginning of the wall, the mix seems to work!

During this week we also had the plaster party. And what a show! Silus, Sarah, Shelly and Shaz (the S team) organized themselves very well. The previous day the created enough of the three different mixes that they used for us to play with and prepared the space for us to work, all the conditions where perfect.


Silus wetting the hessian the night before the party for the plaster to have a good grip.

We had a introduction about what different mixes are made of. One is a clay slip, one is a mix of clay, silt and paper pulp and the third one is a mix of clay, silt and fermented cow dung (which was a little bit smelly but had a great colour). So we rolled up our sleeves and begin to spread these plaster on the walls. I tell you, it is great fun.


The best way was really to press with the palm for the plaster to grip on the hessian.

And what a final result! For the moment none of them has cracked and it really change the energy of the seed room.


From the left to the right we have the paper pulp mix, the fermented dung mix and the clay slip.

Now let’s check the other project. Tom has begun to build the structure for the rabbits to go in. It will be part of the urban design and implemented garden simulating a backyard space of a usual family in the suburb and how can they feed themselves.

Shelly is working on the rocket barbecue. A big learning experience about how to build something efficient and convenient at the same time. For example, which material are we going to use for the insulation? For it to be efficient we need a very good insulation but for it to be convenient we want something very light to be able to move the barbecue around. And from what I have seen they found a perfect answer to this problem. The whole design will come in a later article when the barbecue is fully done and functional.


Shelly using the oxy torch. What an amazing pattern.

In the last article I showed the Biochar cooker that I have build for people to use in the village. We runned it a few time and see what was working well and what was not. There is a lot of variable depending on the material you use for how long the stove is going to burn. But generally it was quiet quick. So firstly I set up a sliding door for us to be able to manage the air flow going in and notice that it help making the process slower and still having enough air to have an efficient combustion that burn all the gases. But even with this extra time it may not be long enough depending on the fuel you are using. So the idea now is that if you need some more cooking time you can just burn the charcoal that you just created. Nothing wrong with that as long as you are able to have a decent cooking time. We did face a problem in the design of my biochar cooker. The chemine is to high and the coal inside are too far apart from the pot. So we inspired ourselves from the Japanese culture and saw that they use a lot of ceramic pot to cook with where they burn charcoal inside. So I transformed my biochar maker cooker into a biochar maker cooker charcoal burner!


That’s the first step of the process, where the fuel gets burned and we need the chemine effect to have a decent draft.

And now we can easily transform this unit into a charcoal burner.


Second step, the unit open in two and you just need to put a grill with your pot on top to harvest the energy of the charcoal burning.

As you can notice the sliding door is almost closed during the first step, where we want the fuel to burn at the slowest rate possible and then in the second phase it is totally open for the charcoal to burn well enough to be able to cook with it. Seeing at the ceramic charcoal burner of Japan I will still need to insulate the bottom part very well. We saw that we were loosing a lot of heat through the steel walls.


 ~Oscar Morand, 12 April 2013, Natural Building and Appropriate Technology Intern

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