The small house also made of clay and straw but using different technique. It was built in five weeks during workshops for youths. It has a wooden framework filled with a mixture of clay and straw. The external walls are thick (45 cm) and no additional insulation is necessary. This house is totally independent of the the electrical grid – it has a small photovoltaic system (power 250 Watt) composed of two pv modules. One of the heating source is semicircular observatory integrated on to the souther wall of the building. The glass of observatory are slanting and thanks to this they absorb maximum amount of solar energy during the day. The heat absorbed during the day is accumulated in the floor. During evening and night the the floor radiates the heat warming the rest of the house. Another heat source is a three-tonne mass stove made of special kind of bricks. Thanks to a double burning process and sophisticated inner canals system this kind of heating is very economical and make the smoke going out of chimney much cleaner and cooler.