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Natural Building & appropriate technology’s blog 05

Article Five of Natural Bldg and Appropriate Tech Internship

This morning we finished our discussion about Rocket Mass Heater as a way to heat our places and why not cook at the same time on them. That is always the interesting part in designing things. Once we understand the principle we can always stack different function on one element to make it more complex and useful. We also had a discussion about human powered technology. It is amazing how much the electricity is helping use in our daily life and how we have forgot the real energy embodied into our electric system. If we had to go on a bike to generate our own electricity we would give up really fast on even using a single lamp!

After all these enlightening conversation we want into the discovery of the biochar.  Here for some information about the biochar and it’s benefits. Because we are in the middle of an Appropriate Technology workshop we focused more on how to create a biochar stove to have our own production here on site instead of commanding it. What do we want to do to have biochar? We want some charcoal. So we need to burn the gases contained in the wood without burning the carbon structure of the wood. This process is called pyrolysis.

Tim Barker already had an experiment on creating a biochar stove but it wasn’t perfect so we improved it with all the students. Here’s a picture of our final stove.


We did reach some high temperature but there was still a lot of smoke. It tells use that our design can be improve. We probably didn’t have enough air flow to burn the gases.

Anyway here is our result, a beautiful biochar that, once activated, can be spread into the gardens.

~Oscar Morand, 21 February 2013, Natural Building and Appropriate Technology Intern

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Natural Building & appropriate technology’s blog 04

Article Four of Natural Bldg and Appropriate Tech Internship

How do we get energy to cook are food? Gas, electricity, yes, we do use them. But most of the world does not have these facilities and what do they use? Wood! Everyday billions of people use wood to cook their food. And millions of them die also because of that, intoxication through carbon monoxide.

Two days ago we learned about solar oven, as a free and clean source of energy to prepare our daily meals. But the sun is not here everyday. What else could we have?

The answer is Rocket Stove! A rocket stove oven for example. But a rocket stove is not only about food. It is mainly about effective combustion. When a piece of wood is burning it releases gases, the smoke. The gases first are a source of pollution but secondly and most importantly they can be burned and provide us with more energy. This is the underlying principle of a rocket stove, to have a clean combustion, to burn the wood and the gases! A well designed rocket stove will not do any smoke.

After understanding the principle and patterns of what a rocket stove is we went to cob the rocket water heater that we have at the Koanga Institute. Our cob mix was mostly clay with powdered pomes and horse manure. With the cob we insulated the rocket elbow for a better efficiency.


Here is an other article about rocket stove water heater system.

Rocket stoves can also be used to heat a big mass to provide a warm environment for a house. This is called a rocket mass heater. It works on the same principle as a kachelofen, well known in Europe in the past.

~Oscar Morand, 21 February 2013, Natural Building and Appropriate Technology Intern


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Natural Building & appropriate technology’s blog 03

Article Three of Natural Bldg and Appropriate Tech Internship

Today, we have learned the three universal laws of thermodynamics:

–       Conservation of energy

–       The disorder in the universe always increases

–      At 0 Kelvin or -273°C all molecular movement stops.

Tim Barker has also shared with us, his three universal laws:

–       It takes always more time than expected,

–       It costs always more money,

–       And we can always do a better job.

These three laws tell you that even with our Wednesday morning session we didn’t finish our solar oven! It has been a real learning lesson for me about how to work together efficiently and about not having too high of an expectation on what we are building. Anyway we are here for ten weeks so we will have the time to finish them after class.

Another interesting topic that has been brought up is the different non-electric cooling systems that one could have. Did you know that on average one third of a household electrical consumption is the cooling devises like fridges and freezers? Do we really need that many things going into a fridge? Definitely not, especially if we are seeking to decrease energy consumption in the future, where our electrical needs will need to be refocused on a more essential level. Here is a solution we came up with:

At 2 meters under ground, the average temperature is 15 degrees. So we could bring the cool of the ground through a cupboard. It is called a Natural Cold Cupboard where the air coming into a pipe through the ground is cooled (or more precisely losses its heat) by conduction and will pass through our food in the cupboard where it will cool the contents. A vent would be installed at the top of the cupboard through the ceiling and it can be painted black or have a vent to drawn the air from underground.

We also discussed evaporation and the concept of wind chill when understanding that human beings have designed an amazing range of different non-electric cooling systems before the invention of electricity and refrigeration.

Here is a picture of a cooling box. 

The yellow bucket is full of water, and will absorb through the piece of tissue.  Once this is wet, the wind passing through the box will take out the heat of the water and cool the whole system.

~Oscar Morand, 20 February 2013, Natural Building and Appropriate Technology Intern

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Natural Building & appropriate technology’s blog 02

Article Two of Natural Bldg and Appropriate Tech Internship

Most efficient solar oven building competition open!!

Four different teams ready to challenge their own understanding and knowledge of thermodynamics and energy flows to first design and after building a solar oven that would have the highest inside temperature. What a day! The morning we had a quick recap of the previous day and like very often, the recap takes longer than expected. Beginning to work on our creation of the day – at 11am we were quiet concerned about having the time to finish. And we did not finish… So we have until Wednesday morning to do the work.

Anyway it was an amazing day. Diving all together deep into our knowledge and sharing our skills with each other in our teams; we ended up with four different designs. We were and still are full of questions to try to improve the efficiency of our solar oven. Is it totally sealed? What are our thermal bridges? Which materials would provide the best insulation? Which material would be strong enough for the frame without being too conductive?

The principle of the solar oven is to harvest the energy of the sun to cook food. We have all experienced the power of a single lens being able to conduct the sun waves of the whole surface of the lens into a single spot and what happens? Fire! What a powerful energy that we live in. At every single second the earth is bathed by this amazing amount of energy.  Let’s go back to our teams. Our designs are quiet different, but the principles and patterns are the same :

–       focus and optimise the energy of the sun on the food.

–       seal and insulate the container to keep the heat inside.

So here we are, still thinking about all how to improve our solar oven for tomorrow and co-create a beautiful peace of art that will also function as an efficient way to cook our meals.

Here is the design of one team, with a big refractor to have a larger catchment area of sun directed into the box.


~Oscar Morand, 19 February 2013, Natural Building and Appropriate Technology Intern

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Kay’s Garden April 2013



The garden is almost looking like a winter garden now. We’ve made around 6 cubic metres of compost this season from our summer garden carbon crops and other crops.


The compost that is going back onto the heavy feeding section of the winter garden is really great compost, made with last winter high brix oats and minerals added. I haven’t needed to add any fertiliser, only compost, and the brassicas are going for it so we’ve made a lot of difference over the 18 months since we began.


I’ve planted my early White garlic and my shallots and potato onions, I’ve divided my Multiplying leeks, my Welsh Bunching onions and my Giant Chives and planted them into the new heavy feeders section of the garden.


I’ve set up a liquid feed barrel again and will use it in a different way to the past. I’m making liquid cow manure and seaweed, and will apply it to the garden after adding vermicast and molasses to it , to hold the water soluble minerals so that they don’t burn up the soil carbon and run off polluting the waterways etc. I’ll probably use it in a watering can to give a boost to things in the heavy feeding section or the root section that look as though they need a boost.


We’re flat out drying basil, perilla, dried beans, peppers and mushrooms in the solar drier, fermenting peppers for paste and making ferments with daikon beetroot and carrots for the winter, and enjoying the Indian Summer.