Energy Foundations – An Integrated System for Building Energy and Structural Foundation
Mentor: Dr. Kerop D. Janoyan
Department: Civil and Environmental Engineering
Geothermal energy has a great potential to provide a constant source of clean and reliable energy to both residential and commercial buildings which consume a major portion of energy supply. The implementation of geothermal energy is fairly simple since heat can be extracted from the earth’s surface at relatively shallow depths. In combination with structural pile foundations, geothermal energy can be used as an alternative energy solution for buildings. This type of ground-source heat extraction has existed for many years predominately in Europe and Asia and has been a clean energy technology with a reported 50% CO2 emissions reduction and a decreased need for primary energy sources to operate. It has been implemented not only in residential but multi-story commercial buildings as well. Such foundation systems are also beneficial since they provide the structural and heating/cooling needs within one system thereby requiring less land usage. Geothermal energy piles are typically laid out in a pattern suitable to support the structure above and a typical cross section consists of concrete, steel reinforcement and high density polyethylene tubing. The tubing and steel reinforcement are arranged together before being lowered into a drilled shaft or borehole and filled with concrete. Once all piles are in place, the tubing is connected to a ground source heat pump which circulates a heat transferring medium throughout. The medium is heated by the ground through heat transfer processes and it is then pumped back into the building and distributed throughout. Energy pile foundations have the ability to use stable ground source heat and raise or lower the building temperature to the desired levels. The objective of this research project is to understand the thermo-mechanical effects of ground source heat pump systems on structural pile foundations. The effects of heating and cooling cycles on the behavior of concrete foundations will be investigated in order to determine the structural performance of the foundation system. The thermo-mechanical effects on the soil-foundation interface will be studied in order to understand the load-transfer mechanism of of the structural loads to the bearing soil strata.  L. Laloui, M. Nuth, and L. Vulliet. "Experimental and Numerical Investigations of the behaviour of a heat exchanger pile." Int. J. Numer. Anal. Meth. Geomech. 30 (2006): 763-81.