{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,22]],"date-time":"2026-01-22T14:33:13Z","timestamp":1769092393529,"version":"3.49.0"},"reference-count":31,"publisher":"MDPI AG","issue":"13","license":[{"start":{"date-parts":[[2024,6,27]],"date-time":"2024-06-27T00:00:00Z","timestamp":1719446400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Foundation for Science and Technology (FCT) of Portugal","award":["SFRH\/BD\/128845\/2017"],"award-info":[{"award-number":["SFRH\/BD\/128845\/2017"]}]},{"name":"Foundation for Science and Technology (FCT) of Portugal","award":["UIDB\/04625\/2020"],"award-info":[{"award-number":["UIDB\/04625\/2020"]}]},{"name":"FCT\u2019s support of the research unit CERIS","award":["SFRH\/BD\/128845\/2017"],"award-info":[{"award-number":["SFRH\/BD\/128845\/2017"]}]},{"name":"FCT\u2019s support of the research unit CERIS","award":["UIDB\/04625\/2020"],"award-info":[{"award-number":["UIDB\/04625\/2020"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Energies"],"abstract":"<jats:p>Ground source heat pump (GSHP) systems depend on the capacity for heat transfer between the system and the ground, and it is good practice to carry out an in situ thermal response test (TRT) to determine the undisturbed ground temperature, the thermal conductivity of the ground, and the thermal resistance of the borehole. Conventionally, a TRT is undertaken in a replica borehole heat exchanger (BHE); however, alternative methods have been developed that can provide continuous depth-resolved temperature recordings. The enhanced TRT (ETRT) uses a hybrid cable system which incorporates a resistance heating wire to provide a linear heat source and a fibre optic cable to measure the temperature along the length of the borehole. In this paper, a case study is presented in which a TRT and ETRT were carried out in the same BHE to evaluate its thermal response and estimate the thermal characteristics of the ground. After a brief introduction of both methods and their interpretation, a comparison between them is presented regarding their advantages and disadvantages using the results of the performed tests, which revealed an 8% difference in the soil thermal conductivity values, averaged over the length of the BHE.<\/jats:p>","DOI":"10.3390\/en17133161","type":"journal-article","created":{"date-parts":[[2024,6,27]],"date-time":"2024-06-27T05:11:39Z","timestamp":1719465099000},"page":"3161","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["The Implementation and Comparison of Conventional and Enhanced Borehole Thermal Response Tests: A Case Study"],"prefix":"10.3390","volume":"17","author":[{"given":"Jo\u00e3o","family":"de Sousa Figueira","sequence":"first","affiliation":[{"name":"CERIS (Civil Engineering Research and Innovation for Sustainability), Instituto Superior T\u00e9cnico, 1049-001 Lisboa, Portugal"}]},{"given":"Stefan","family":"Nachbaur","sequence":"additional","affiliation":[{"name":"ENERCRET Gmbh, 6832 R\u00f6this, Austria"}]},{"given":"Stefan","family":"Wehinger","sequence":"additional","affiliation":[{"name":"ENERCRET Gmbh, 6832 R\u00f6this, Austria"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1203-4710","authenticated-orcid":false,"given":"Peter","family":"Bourne-Webb","sequence":"additional","affiliation":[{"name":"CERIS (Civil Engineering Research and Innovation for Sustainability), Instituto Superior T\u00e9cnico, 1049-001 Lisboa, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2024,6,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2461","DOI":"10.1016\/j.renene.2006.12.014","article-title":"Ground heat exchangers\u2014A review of systems, models and applications","volume":"32","author":"Florides","year":"2007","journal-title":"Renew. Energy"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"578","DOI":"10.1016\/S0375-6505(03)00060-9","article-title":"Current status of ground source heat pumps and underground thermal energy storage in Europe","volume":"32","author":"Sanner","year":"2003","journal-title":"Geothermics"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"445","DOI":"10.1016\/j.apenergy.2014.09.029","article-title":"Strategic optimization of borehole heat exchanger field for seasonal geothermal heating and cooling","volume":"136","author":"Bayer","year":"2014","journal-title":"Appl. Energy"},{"key":"ref_4","unstructured":"Sanner, B., Hellstr\u00f6m, G., Spitler, J., and Gehlin, S. (2005, January 24\u201329). Thermal Response Test\u2014Current Status and World-Wide Application. Proceedings of the World Geothermal Congress, Antalya, Turkey."},{"key":"ref_5","unstructured":"(2015). Geotechnical Investigation and Testing\u2014Geothermal Testing\u2014Determination of Thermal Conductivity of Soil and Rock Using a Borehole Heat Exchanger (Standard No. ISO 17628:2015)."},{"key":"ref_6","first-page":"131","article-title":"Comparison of four models for thermal response test evaluation","volume":"109","author":"Gehlin","year":"2003","journal-title":"ASHRAE Trans."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"109575","DOI":"10.1016\/j.rser.2019.109575","article-title":"Advanced thermal response tests: A review","volume":"119","author":"Wilke","year":"2020","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_8","unstructured":"Gehlin, S. (2002). Thermal Response Test\u2014Method Development and Evaluation. [Ph.D. Thesis, Lulea University of Technology]."},{"key":"ref_9","unstructured":"Aranzabal, N., Martos, J., Montero, A., Soret, J., Garc\u00eda-Olcina, R., and Torres, J. (July, January 29). Design and test of an autonomous wireless probe to measure temperature inside pipes. Proceedings of the 28th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, Pau, France."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"399","DOI":"10.1016\/j.geothermics.2009.06.002","article-title":"An improved thermal Response test for U-tube ground heat exchanger based on optical fiber thermometers","volume":"38","author":"Fujii","year":"2009","journal-title":"Geothermics"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"312","DOI":"10.1016\/j.apenergy.2013.01.024","article-title":"Distributed thermal response test on pipe-in-pipe borehole heat exchangers","volume":"109","author":"Palm","year":"2013","journal-title":"Appl. Energy"},{"key":"ref_12","first-page":"271","article-title":"Glutsch Erfahrungen aus der Praxis mit dem Enhanced Geothermal Response Test (EGRT)","volume":"11","author":"Heidinger","year":"2008","journal-title":"Geothermics"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"V\u00e9lez M\u00e1rquez, M., Raymond, J., Blessent, D., Philippe, M., Simon, N., Bour, O., and Lamarche, L. (2018). Distributed thermal response tests using a heating cable and fiber optic temperature sensing. Energies, 11.","DOI":"10.3390\/en11113059"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Galgaro, A., Pasquier, P., Schenato, L., Cultrera, M., and Dalla Santa, G. (2018, January 18\u201319). Soil Thermal Conductivity from Early TRT Logs Using an Active Hybrid Optic Fibre System. Proceedings of the IGSHPA Research Track, Stockholm, Sweden.","DOI":"10.22488\/okstate.18.000023"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Vieira, A., Alberdi-Pagola, M., Christodoulides, P., Javed, S., Loveridge, F., and Nguyen, F. (2017). Characterisation of ground thermal and thermo-mechanical behaviour for shallow geothermal energy applications. Energies, 10.","DOI":"10.3390\/en10122044"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"110336","DOI":"10.1016\/j.rser.2020.110336","article-title":"Actively heated fiber optics based thermal response test: A field demonstration","volume":"134","author":"Zhang","year":"2020","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_17","unstructured":"Figueira, J., and Vieira, A. (2016, January 19\u201323). M\u00e9todos de caracteriza\u00e7\u00e3o t\u00e9rmica do solo para aproveitamentos geot\u00e9rmicos superficiais. Proceedings of the 15th Geotechnics National Congress, Porto, Portugal."},{"key":"ref_18","unstructured":"van Wijk, W.R. (1963). Physics of Plant Environment, Technological University Eindhoven."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Johansen, O. (1977). Thermal Conductivity of Soils, Cold Regions Research and Engineering Laboratory.","DOI":"10.21236\/ADA044002"},{"key":"ref_20","first-page":"25","article-title":"Statistical-Physical Model of Thermal Conductivity in Soil","volume":"XXV","author":"Usowicz","year":"1992","journal-title":"Pol. J. Soil Sci."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"213","DOI":"10.1016\/S1364-0321(99)00018-0","article-title":"Ground heat transfer effects on the thermal performance of earth-contact structures","volume":"4","author":"Rees","year":"2000","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_22","unstructured":"(2013). Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus (Standard No. C177-13)."},{"key":"ref_23","unstructured":"(2015). Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus (Standard No. C518-15)."},{"key":"ref_24","unstructured":"(2013). Standard Test Method for Thermal Conductivity of Solids Using the Guarded Comparative-Longitudinal Heat Flow Technique (Standard No. E1225-13)."},{"key":"ref_25","unstructured":"(2014). Standard Test Method for Determination of Thermal Conductivity of Soil and Soft Rock by Thermal Needle Probe Procedure (Standard No. D5334-14)."},{"key":"ref_26","unstructured":"(2016). Standard Test Method for Thermal Conductivity of Plastics by Means of a Transient Line-Source Technique (Standard No. D5930-16)."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Tong, X.C. (2011). Advanced Materials for Thermal Management of Electronic Packaging, Springer Science & Business Media.","DOI":"10.1007\/978-1-4419-7759-5"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Chiasson, D. (2016). Geothermal Heat Pump and Heat Engine Systems: Theory and Practice, Wiley. [1st ed.].","DOI":"10.1002\/9781118961957"},{"key":"ref_29","unstructured":"AP Sensing (2024, May 26). GeoDTS N4388A. Available online: https:\/\/www.apsensing.com\/fileadmin\/001___PORTAL__\/001_documents\/brochures\/AP-Sensing_GeoDTS-geothermal-rating_0210.pdf."},{"key":"ref_30","unstructured":"Kiesel, K., Vuckovic, M., Orehounig, K., and Mahdavi, A. (2012, January 20\u201322). Analysis of micro climatic variations and the urban heat island phenomenon in the city of Vienna. Proceedings of the EURA Conference, Vienna, Austria."},{"key":"ref_31","unstructured":"Rees, S.J. (2016). Calculation of borehole thermal resistance. Advances in Ground-Source Heat Pump Systems, Woodhead Publishing. [1st ed.]."}],"container-title":["Energies"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1073\/17\/13\/3161\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T15:06:05Z","timestamp":1760108765000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1073\/17\/13\/3161"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,6,27]]},"references-count":31,"journal-issue":{"issue":"13","published-online":{"date-parts":[[2024,7]]}},"alternative-id":["en17133161"],"URL":"https:\/\/doi.org\/10.3390\/en17133161","relation":{},"ISSN":["1996-1073"],"issn-type":[{"value":"1996-1073","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,6,27]]}}}