CEPA CÁCERES
El trabajo con los materiales y herramientas necesarios para construirlo forma parte de su rutina habitual, puesto que trabajan con el cartón, la cola, el cutter, la guillotina,... en el área de encuadernación. Aplicar sus conocimientos en este proyecto les plantea la idea del medio ambiente y del ahorro energético. Les muestra que existen fuentes de energía diferentes a las que pueden acceder con creatividad. Y lo más importante es que les muestra que cada uno de ellos puede hacer algo que beneficia al medio ambiente y a toda la sociedad.
El horno solar.
Es un horno que funciona sólo con el sol, sin cables ni pilas ni otros tipos de combustible.Consiste básicamente en una caja que recoje el calor del sol y lo mantiene. Y sirve para cocinar.
Una vez concebida la idea se pone en marcha el proceso.
En el caso que nos ocupa partíamos de una experiencia exitosa, de un horno que ya había funcionado. Algunas de las piezas esenciales – el cristal, la pieza metálica- procedían de este.
Primero es el proceso de documentación, de recogida y asimilación de información. Hallamos ideas interesantes en el gran almacén de Internet. Se puede hacer un horno solar con materiales desechables, concretamente con dos cajas de cartón, el cristal de una ventana vieja, periódicos viejos y una bandeja metálica en desuso. Para encolar utilizamos la cola del taller de artes gráficas. Sólo tenemos que comprar un rollo de papel de aluminio alimentario.
Como los materiales que poseemos son muy heterogéneos, la primera misión es trazar un plan para armonizarlos, para que cada pieza encaje en el conjunto.
Partimos de dos elementos que no son modificables: el cristal y la pieza metálica. Sus medidas van a servir de base al producto final.
A continuación forramos todo el interior de la caja con papel de aluminio para que refleje el calor hacia dentro. Como el horno es bastante grande y puede tener bastante peso, pegamos en el fondo de la caja varias tiras de cartón de canto para que soporten el peso del interior del horno, evitando que el aislante se aplaste y deje de cumplir su papel.
En la segunda caja debe caber la pieza metálica y debe ser menos amplia que el cristal, para que se asiente sobre sus bordes. También debe ser menos profunda que la grande para que quepa una capa de aislante debajo.
El primer paso es recubrirla de papel de aluminio por dentro y por fuera. Luego se coloca dentro de la otra rellenando con el aislante todos los huecos. La parte superior debe quedar diáfana, para que entre el sol y se pueda acceder al área de cocción. Por eso, se aprovechan las tapas para unirla a la caja grande.El siguiente paso es unir las dos cajas, pegando sobre la grande las tapas abiertas de la pequeña. Pero con ello aumenta el perímetro de la caja grande e impide que la tapadera del horno encaje. Cambiamos el diseño y se doblan y pegan las tapas en la cara interior de la caja grande. Así concluye la fabricación del cuerpo del horno.
Abrimos una ventana abatible que coincide exactamente con la boca del horno. El interior la hoja de esta ventana va forrada de papel de aluminio para que refleje el sol hacia el horno. Unos topes de cartón nos permiten ajustar su inclinación a la del sol.
Como el cristal es un poco pesado lo adherimos a la parte interior de la tapadera con una estructura de piezas de cartón superpuestas y encoladas, de modo que la tapadera forma un todo compacto.
Esta actividad nos ha permitido desarrollar en los alumnos el sentido cívico y la conciencia de que todos debemos y podemos colaborar en el desarrollo de una sociedad sostenible.
También aprendemos a aprender, pues vamos resolviendo sobre la marcha los problemas que se plantean cuando nuestro diseño original se aparta de la realidad.
Cáceres 2012MAKING A SOLAR OVEN.
An example of best practice
The main idea that informs our project is "Let's Do It", learning by doing. So, making a Solar Oven with our Basic Vocational Training (PCPI) students is a part of this idea.
By doing so we hope to confront them with the idea of the Environment problems. We expect rising their awareness of the energy constraints, the man induced global changes and the importance of acting quickly to avoid further damage.
It is important for them to know that everything they do leaves a carbon footprint that damages the environment. But it is more important that they know they can do something to lessen their negatived impact and that it is not very difficult or expensive.
Key competences addressed:
Civic competences.
Learning to learn.
Civic competences
By this activity we'd like to raise the students ability to display solidarity by showing an interest and helping to solve problems affecting the local and the wider community.
Also their sense of belonging to a community and their personal responsibility in tackling those problems.
Learning to learn.
It comprises the disposition and ability to organize and regulate one's own learning. It includes the ability to solve problems, to acquire, process and evaluate new knowledge and to apply it and new skills in a variety of contexts: at home, at work, in education and training.
The solar oven.
Roughly it is a box that allows solar energy getting in and keeps the heat inside, so that we can cook with that heat.
In our case, the idea comes from an oven that had already worked.
From this idea we proceeded to gathering more information. We found many very helpful web pages about the making of those ovens.
Materials.
After looking at the information we decided that we needed two cardboard boxes, one a bit bigger than the other, a glass to cover the oven, so that the sun could get in, and the heat remained inside by producing the greenhouse effect. Also we needed kitchen aluminium paper to reflect the sunlight, a dark iron piece to catch the heat inside the oven, and old newspapers to make the insulation layer between the two boxes.
Finally we needed items very familiar to the students – cutters, scissors, rulers, glue- due to their book wrapping expertise.
We had already the glass from the old oven -It came from an old window- and the piece of iron -a discarded bread baking plate. Then we bought the aluminium paper, and it was not difficult to get the boxes and the old newspapers.
The tools and the glue were already in the school printing workshop.
The making.
The idea and the remains of the old oven were presented to the students and the making process took off.
The first problem to address was finding out how to do it, what we needed considering.
There were two pieces that were not easily modified; the glass and the piece of iron. So, their size was our starting point. The big box should be, at least, as wide as the glass and the little box should be larger than the piece of iron and narrower than the glass to prevent its falling inside.
The boxes were adapted to the size needed.
To get a proper cover to the oven, we cut the upper part of the big box, and there resulted a big part, about 50 cm.(19 inch) deep and a 10 cm (4 inch) deep part.
All the inner surface of the big box was covered with glued aluminium paper.
The little box was 90 X 75 X 40. The glass was a bit heavy. The insulation under the box would be made of paper balls from newspapers. To avoid it being flattened under the weight, we decided to stick, on the bottom of the big box, some 10 cm cardboard strips on edge for the little box to lay upon.
Some students made paper balls with the newspapers while some others covered the inside and outside of the box with aluminium paper. Then it was placed inside the big one.
After all the spaces were packed with paper balls it was time to join both boxes together and to seal all the cracks.
The theory we got said that the covers of the little box were to be opened and glued over the big box. However, doing so, the width would increase, and the cover we had would not fit the oven any more. Instead of bending them to stick them in the outside, we did it to glue them on the inside part of the big box, keeping its original size. Now the body of the oven was completed and all the creaks sealed. It was the greenhouse effect moment.
Firstly the cover was readjusted to fit the oven. Then we opened a window the size of the little box (the mouth of the oven). The resulting flap was covered with aluminium paper. A couple of cardboard stripes allow us to rise the flap or get it down to reflect the sun into the oven.
The glass was fixed to the inner part of the cover by cardboard stripes glued together. Now it is a coherent body, without cracks that keeps all the heat inside the oven.
The students and the teachers involved are very happy with the results.
Cáceres 2012
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