Earth heat exchanger for greenhouses, foil tunnels and the like, in which a device (1) having three sections (A, B, C) is put vertically into the ground of the greenhouse or of the foil tunnel. In this case, section A is above ground, section B underground in the region of the earth with temperature variations according to time of day, and section C underneath this. Provided in sections A and B are two mutually parallel and at least approximately vertical flow ducts with at least approximately the same cross-section, which are interconnected at the top of section A and pass into the one-part section C at the bottom of section B. The device is filled to above the connection in the top of section A with liquid heat-exchange medium. Preferably, one of the two flow ducts is provided on the sun-side, blackened in section A and heat-insulated in relation to the soil in section B. <IMAGE>
