A critical review on the current knowledge of geothermal energy piles to sustainably climatize buildings

Greenhouse gas emissions produced by fossil fuels are causing a slow change of the climate's conditions. Air conditioning systems in engineering superstructures demand a considerably amount of the existing carbon related energy sources, which are pollutant and non-renewable. In this regard many European and some other developed countries have addressed Shallow Geothermal Energy Systems as a renewable source of energy worthy of investment and development. These systems refer to the exploitable thermal energy in the shallow subsurface of the earth, usually exploited using ground source heat pumps to exchange and store ground heat. These energy systems can provide heating and cooling to buildings, helping the reduction of harmful gas emissions. This paper therefore addresses the current knowledge on the use of geothermal energy piles to enhance the energy efficiency of buildings, based on an extensive literature review on the subject. Important up-to-date general aspects of the use of these renewable energy systems are given, based on laboratory, field, and numerical studies. Key points for future research and development are critically discussed, and conclusions for its enhancement are finally summarized.