Byhaven2200 is a living and thriving garden and community. There is lots of tasks to fulfill along the year, and every season we find new activities and things to do. It started some years back, when the main focus was on growing vegetables in the city and on being sustainable and ecologic in a practical way.
Now the social aspect has grown more and more important in bringing life to the garden; or at least we are now much more able to see how important it is.
The star project of the year has been the kitchen and specially its new clay oven. Building it and using it have been a very pleasurable experiences, and very social as well. A big deal of its beauty lies on its wild nature, as we only had a few guidelines on how to build it and decorate it. Moreover, we followed our hearts and ideas of the volunteers that engaged in the project.
A ‘stenovn’ is a very smart invention that uses energy very efficiently. It´s basically a chamber with a door and a smoke exit – a chimney if you will. Our new oven at Byhaven2200 is made of clay bricks, clay, sand, straw, wood and living soil and plants.
Clay bricks are made of what’s known as refractive material. They can absorb a huge amount of energy and release it slowly afterwards. When an open fire would project/spit a great deal of its energy up in the sky in the form of hot air, a closed ‘stenoven’ makes sure that all the heat is released when the burning of wood heats up its walls and not so much the air that flows in – mainly because there is not that much air flowing in!
Due to the slower input of oxygen (air), the wood burns more slowly. The oven also absorbs the radiative heat more efficiently (check the picture!) that otherwise would just spread around.
Since the hot air that escapes the oven does so slowly through the chimney, changes in its shape and size allows for a better use of the remnant heat. Our ‘stenovn’ does not have an extremely long chimney, but long enough to trap the heat inside and release the smoke up in the air.
Once the fire starts to die off, the walls of the oven are warm enough to cook food it remains like that for at least 12 hours. This is what allows us to bake loads of pizza very quickly and efficiently, one after the other, providing a great foundation for fantastic parties!
And talking about foundations that was the very first step to build the oven: the wooden structure on which it lays. It later became a fantastic cupboard where we now keep the cooking equipment and other stuff. Unfortunately this step was the only one taking a looooong time, as we ended up redoing it a bunch of times, before we built the actual oven!
How the oven was built
The oven was built inside out. We started with a layer of bricks masterfully set together with skills and mortar by Kenn and other experienced builders that are volunteering in the garden. This conforms the chamber where the food is cooked. These clay bricks are the main structure, but more layers ensure a good use of the energy. A shallow layer of mortar over the structure came next. The mortar is made of clay, sand and water. Clay is the sticky part, while sand and water make the mixture user-friendly. The proportion is around one part clay to four/three parts of sand and then adding water until the mixture becomes a workable paste.
One problem with mortar though is that it can be quite fluid, so it might need some additional help to keep its shape until it dries. This also means that at this point the oven needed protection from the rain, so a temporary roof was set. The current roof is of course much better, but we’ll come into it later.
The following layer was a mixture of mortar and hay (cob) – more durable and insulating layer to help keep the heat inside. We used wire mesh to make sure it would keep its shape, and let it dry for a week. In a dry climate like one you could find in Spain it would take less than a day, but Copenhagen is too rainy and too close to the sea.
The oven was then ready to be used – and we used it! But the looks and the protection was far from done, and so a new mortar layer was laid and a mosaic was added. We used upcycled materials, ranging from old claypots to pistachio husks donated by locals from the neighborhood as well as garden volunteers and their families.
You should come to the garden to check it out – we are quite proud of the result!
And finally, but still quite important, we managed to build a quite neat roof to protect the oven from the rain – mortar is not like concrete; it melts with water! With some wood plates, an electric borer and lots of fun, we set a green roof over the oven, crowded with strawberries – just look at how beautiful it is!
Protection, CO2-reduction and more yield – Multifunction!
The oven works now as a major attractant for bypassers, both when it’s active and off duty, and as a perfect excuse to visit the garden and enjoy this little piece of Earth that we are managing.
It is definitely an improvement in the zone and we are hoping that everybody in the neighborhood, visitors and residents alike, will use it, enjoy it and take care of it J
Vi ses i byhaven2200!