Numerical modelling of energy geo-structures for building retrofitting

Energy piles (EPs), consisting in piled foundations equipped with heat exchangers, have been extensively studied in recent years, both from the thermo-mechanical response and energy performance points of view. However, most research refers to typical rotary bored, CFA or precast driven, medium diameter piles. Little attention has been devoted to so-called energy micropiles (EMPs), representing an opportunity to provide at the same time energy and structural retrofitting to existing buildings. Existing studies show that EMPs overall may thermally perform differently to EPs, but they are comparable in terms of specific heat flux.

In this work, a 3D FE numerical model is employed to perform a comprehensive parametric study considering design factors that are peculiar to EMPs, to assess the most important parameters to maximise their energy performance. The parameter space is efficiently explored resorting to a statistically-based Taguchi approach. Then, the model is employed to compare the overall energy performance of realistic EP and EMP foundation solutions, under the same building and underground conditions. Finally, practical guidance is provided about the optimal choice of design factors to achieve the best thermal performance whenever EMPs  are to be used based on geotechnical/structural design.

 

Acknowledgement: The second author wishes to acknowledge support from the EU’s Horizon 2020 Research and Innovation programme under Grant Agreement No 810980 - ENeRAG.