Acta Geotechnica

, Volume 10, Issue 2, pp 209–218 | Cite as

A comparison of laboratory and in situ methods to determine soil thermal conductivity for energy foundations and other ground heat exchanger applications

  • Jasmine E. LowEmail author
  • Fleur A. Loveridge
  • William Powrie
  • Duncan Nicholson
Research Paper


Soil thermal conductivity is an important factor in the design of energy foundations and other ground heat exchanger systems. It can be determined by a field thermal response test, which is both costly and time consuming, but tests a large volume of soil. Alternatively, cheaper and quicker laboratory test methods may be applied to smaller soil samples. This paper investigates two different laboratory methods: the steady-state thermal cell and the transient needle probe. U100 soil samples were taken during the site investigation for a small diameter test pile, for which a thermal response test was later conducted. The thermal conductivities of the samples were measured using the two laboratory methods. The results from the thermal cell and needle probe were significantly different, with the thermal cell consistently giving higher values for thermal conductivity. The main difficulty with the thermal cell was determining the rate of heat flow, as the apparatus experiences significant heat losses. The needle probe was found to have fewer significant sources of error, but tests a smaller soil sample than the thermal cell. However, both laboratory methods gave much lower values of thermal conductivity compared to the in situ thermal response test. Possible reasons for these discrepancies are discussed, including sample size, orientation and disturbance.


Energy foundations Ground source heat pumps Needle probe  Thermal cell Thermal conductivity  



The authors would like to thank Harvey Skinner for his help in the design, build and instrumentation of the apparatus. The soil samples were provided by Concept Engineering Consultants Ltd and Arup. The TRT was carried out by GECCO2, with fibre optic temperature and strain monitoring by University of Cambridge. We are also grateful for the site support from Canary Wharf Contractors Ltd and Marton Geotechnical Services Ltd. This work forms part of a larger project funded by EPSRC (ref EP/H0490101/1) and supported by Mott MacDonald Group Ltd, Cementation Skanska Ltd, WJ Groundwater Ltd and Golder Associates.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Jasmine E. Low
    • 1
    Email author
  • Fleur A. Loveridge
    • 1
  • William Powrie
    • 1
  • Duncan Nicholson
    • 2
  1. 1.Faculty of Engineering and the EnvironmentUniversity of SouthamptonSouthamptonUK
  2. 2.Ove Arup and Partners LimitedLondonUK

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