Resumen

The method involves arranging a combined structure between a biomass element (13) and plastic capillary tube. The heat of compost and/or fermentation material (15) of biomass element is exchanged with the heat output from the plastic capillary tube (12). Several heaps of compost and/or fermentation materials are inserted into several planes of plastic capillary tube, such that water is heated by the heat emitted from the compost/fermentation material. Water from a hot water tank made of polypropylene material is supplied to the inner side of heap of compost and/or fermentation material.