On Saturday, April 12th 2008, the Tamera Peace Research Center near Colos invited interested people to get to know different experimental straw-bale/adobe buildings on its site. Gernot Minke, professor for adobe building at the University of Kassel, Germany, was there and explained the advantages of this technique.
Building with earth has a long tradition in Portugal. The combination with new building techniques and materials like straw and green roofs as well as with solar architecture makes it possible to construct modern architecture, futuristic design, domes and arches, and to provide the comfort of a modern life. Building with adobe and straw is an alternative which saves money and manpower, creates a good indoor climate and combines old skills with modern techniques.
Eight meters high are the walls of Tamera‘s Aula. With its 300 places, the auditorium of the Peace Research Center is the biggest straw-bale/adobe building in the Iberian peninsula. With its green roof and the earth-coloured walls it fits harmoniously into the landscape – as if it had a cloak of invisibility. When visitors step in, however, they are amazed by its grandeur. The timber of the construction and their harmonious proportions give a feeling of magnitude.
"Almost like in a cathedral“, one of the visitors who came from Lisbon states.
The Aula consists of a wooden construction which was stacked with straw-bales and plastered from the inside and the outside with clay. For the outer wall the clay was mixed with lime to protect the wall from the rain. The roof is green: grass and herbs grow and make the roof as green as the landscape.
"How long will such a house be stable?“ a visitor asks a little anxiously.
"As long no mechanical damage occurs, for ever“, Professor Minke answers smiling. He has heard these questions many times. In his 71 years long life, he has built hundreds of these houses in South America, Africa and Germany. In his own home, made of clay and straw, he has been living for 14 years.
"Why straw bales?“ the visitors want to know. "Because of two reasons“, Professor Minke answers. "To build with straw bales is much faster because they are big. This saves labour costs. The second reason is their best quality of insulation. But,“ he adds, "you have to know how to do it.“
In his Institute for Biological Building in Kassel, he and his team developed numerous improvements in the work with straw bales, clay and green roofs. Tamera for him has become an experimental site for new techniques.
On of them is the "three-arches house“: the first self-carrying straw-bale house worldwide. The arches of the house are built without a wooden construction, only with straw bales. Specially for that his institute developed a machine which cut every straw bale to exactly the right angle.
Another house the visitors can visit is the Hogan – an Indian style wooden construction with a special light pyramid on top.
"Are these houses earthquake safe?“ somebody asks.
"In Guatemala I build houses like that specially for earthquake danger zones as they are the most secure buildings which exist. The wood is elastic, and the straw bales go with the movement. The only thing that happens during an earthquake is that the clay plaster falls off.“ Straw-bale buildings are additionally fire proof.
Prof. Minke builds only houses with green roofs. In Portugal, they are still rare.
"We have good results with them however“, states Beate Möller, Tamera‘s architect.
"We only had to water our big green roof on top of the Aula in the first year. Now the plants turn yellow in the summer season but with the first rain they turn green again. Green roofs have an excellent insulation quality. The temperature in the houses with green roofs is always comfortable. "
Professor Minke and Beate Möller are sure that the two innovations – building with straw bales and building green roofs – can work very well for the Alentejo.
"Building with adobe has a long tradition in Portugal. This tradition can now be combined with new scientific techniques. Like this, building with biological material can easily meet the needs of modern comfort and the desire for futuristic design.“
