Review A review on energy piles design, sizing and modelling Jevgeni Fadejev a, b, * , Raimo Simson a , Jarek Kurnitski a, b , Fariborz Haghighat c a Tallinn University of Technology, Ehitajate tee 5,19086, Tallinn, Estonia b Aalto University, School of Engineering, Rakentajanaukio 4 A, FI-02150, Espoo, Finland c Concordia University, Department of Building, Civil and Environmental Engineering, H3G 1M8c, Montreal, Canada article info Article history: Received 26 August 2016 Received in revised form 18 January 2017 Accepted 19 January 2017 Available online 24 January 2017 Keywords: Energy piles Sizing Modelling Fundamental scheme Thermal storage abstract Boreholes and energy piles coupled with ground source heat pump plants utilize renewable geothermal energy for buildings heating and cooling purposes and need proper design and sizing in order to end up with high plant efficiency. This paper conducted a review of available scientific literature, design standards and guidelines on energy piles performance within the framework of the IEA-ECES Annex 31 . Main aspects covered were typical plant solutions, configurations of energy piles and their thermal response test per- formance, available analytical and numerical models with their main features and application in com- mercial software and design manuals. Four typical fundamental schemes of geothermal plant with energy piles were found, both suitable for cold and hot climate applications. Properly sized heat pump systems with energy piles were characterized with high overall system SCOP values higher than 4.5, while some case studies reported two times smaller SCOP values that illustrates the effect of proper design and sizing of such systems. The lack of specific heat extraction values which could be determined based on the climate and energy pile application show the need to develop general procedures for early stage energy pile sizing that would allow quick estimates of the heat extraction/rejection potential and system performance with reasonable accuracy for conceptual design. Most of available software is borehole oriented and will fit for energy piles sizing if software supports variable ground surface temperature boundary conditions, which, however is not implemented in most of software packages. Expected software features to be implemented are water advection and multiregional surface boundary heat transfer. © 2017 Elsevier Ltd. All rights reserved. Contents 1. Introduction ...................................................................................................................... 391 2. Fundamental schemes of plants with energy piles ..................................................................................... 391 3. Energy pile configurations ......................................................................................................... 394 4. Energy pile modelling .......................................................... .................................................. 396 4.1. Analytical models ........................................................................................................... 399 4.2. Numerical models ........................................................................................................... 402 4.2.1. Finite difference ...................................................................................................... 402 4.2.2. Finite volume ....................................................... ................................................ 403 4.2.3. Finite element ....................................................................................................... 403 5. Energy pile sizing and design ....................................................... ............................................... 403 6. Conclusions ...................................................................................................................... 405 Acknowledgment .................................................................................................................. 406 References ......................................................................................................................... 406 * Corresponding author. Tallinn University of Technology, Ehitajate tee 5,19086, Tallinn, Estonia. E-mail address: jevgeni.fadejev@ttu.ee (J. Fadejev). Contents lists available at ScienceDirect Energy journal homepage: www.elsevier.com/locate/energy http://dx.doi.org/10.1016/j.energy.2017.01.097 0360-5442/© 2017 Elsevier Ltd. All rights reserved. Energy 122 (2017) 390e407