Energy piles and diaphragm walls for heat transfer from and into the ground
H. Brandl
Abstract
Energy piles or diaphragm walls for the extraction of geothermal energy and/or the transferring and/or storage of thermal energy in the ground have proved very suitable for heating and/or cooling of buildings. This innovative technology provides not only substantial long-term cost savings in relation to conventional energy systems but also a valuable contribution to environmental protection by reducing fossil energy utilisation. The paper describes the principles, illustrates case histories, and reports on the results of in-situ measurements. It has been found that the thermally induced strain effects caused by a proper operation of the energy system are significantly smaller than those developing during hydration of large diameter bored piles. Consequently, they have no relevant influence on the shaft resistance if deep temperatures in the energy absorber system are avoided. The paper gives also recommendations for the engineering practice.