Open access GSHP measurement data and uncertainty analysis at 3rd Annex 52 expert’s meeting

The 3rd international experts’ meeting of IEA HPT Annex 52, titled Long-term measurements of GSHP system performance in commercial, institutional and multi-family buildings, gathered 28 experts from eight countries in Helsinki, Finland, on May 23-24th.

Publications and open access data sets

Annex 52 has now run for a year and a half, and at the time of the meeting in Helsinki, two international journal papers (Naicker and Rees 2018, Spitler and Gehlin 2019) and four peer-reviewed conference papers (Gehlin et al. 2018, Andersson and Rydell 2018, Abuasbeh and Acuña 2018, Gehlin and Spitler 2019) related to the Annex 52 case studies have been published ( The two published journal papers describe comprehensive GSHP system performance analyses with uncertainty analyses, and are supplemented by open access reference data sets. This fulfills one of the Annex 52 goals; to provide at least one set of open access GSHP system long-term performance measurement data, as a useful resource for researchers and engineers.

System boundary schema

Spitler and Gehlin (2019) presented a survey of six published system boundary schema for GSHP systems, of which one is the SEPEMO boundary schema. The six boundary schema are all similar, but vary with regards to inclusion of buffer tanks, supplementary heating and cooling, whether they are defined for heating only or for both heating and cooling, and the existence of a boundary for the ground source only. The SEPEMO boundary schema, which is used in the EU renewable energy directive, has the advantage of being defined for heating and cooling respectively, but is limited in how it accounts for supplemental heating and cooling. It does not allow the performance of the ground source to be evaluated by itself. Nor does it explicitly address buffer tanks.

A preliminary new boundary schema that seeks to better reflect the complexity of larger GSHP systems was proposed at the meeting. These systems often provide both heating and cooling, sometimes simultaneously. The new boundary schema is an extension of the SEPEMO schema, but contains boundaries around the ground source and on both sides of any buffer tanks. Another feature is that supplementary heating and cooling are addressed at all boundaries. This new suggested boundary schema will now be tested and further discussed at coming meetings.

Uncertainty analysis help and instrumentation guideline

A draft guide to GSHP field measurement uncertainty analysis has been compiled by Jeff Spitler, as help for Annex 52 participants in their case study performance analyses.

A first preliminary draft of the Subtask 2 instrumentation guideline was discussed at the meeting in Helsinki. The guideline will contain a list of different instrumentation groups, and will cover calibration, placement, measurement frequency, time lags, data processing and key performance indices. Acoustic measurements and a section on Distributed Temperature Sensor (DTS) monitoring will be included in the guideline.

40 case studies in 7 countries

With Sweden, the USA, the UK, the Netherlands, Finland, Germany and Norway as confirmed Annex participants, 40 performance-monitoring projects are now part of the annex work.

  • Sweden: 16 borehole systems, 2 groundwater systems
  • USA: 1 borehole system
  • UK: 2 borehole systems, 1 combined borehole+energy pile system, 1 groundwater system
  • Netherlands: 4 groundwater systems
  • Finland: 1 borehole system
  • Germany: 3 borehole systems and 3 energy pile systems
  • Norway: 5 borehole systems and 1 groundwater system

Annotated bibliography

The annotated bibliography on long-term performance monitoring of GSHP systems, which is part of Subtask 1, now contains 65 publications related to 55 long-term performance case studies of GSHP systems worldwide. More publications will be added during the course of Annex 52.

New members and up-coming meetings

HPT Annex 52 is open to participation from countries that belong to the IEA HPT, ECES and Geothermal Technology Collaboration Programs, and the deadline for joining the annex is October 2019.

The fourth Experts’ meeting will take place in London, UK, on September 16th-17th 2019.

The fifth Experts’ meeting will take place in Germany in the beginning of 2020.

Annex 52 related publications

Scientific journal papers:

Naicker, S. S. and S. J. Rees. (2018). Performance Analysis of a Large Geothermal Heating and Cooling System. Renewable Energy 122:429-42.

Measurement data available as open access at

Spitler, J.D. and S.E.A. Gehlin. (2019). Measured performance of a mixed-use commercial-building ground source heat pump system in Sweden. Energies 2019, 12, 2020; doi:10.3390/en12102020. Open access at:

Measurement data available as open access supplementary material.

Conference papers

Gehlin, S. and J.D. Spitler. (2019). IEA HPT Annex 52 – Measuring GSHP system long-term performance. European Geothermal Congress 2019 in Den Haag, the Netherlands. June 11-14 2019.

Abuasbeh, M., Acuña, J. (2018). ATES System Monitoring Project, First Measurement and Performance Evaluation: case study in Sweden. IGSHPA Research Track 2018, Stockholm, Sweden, September 18th 2018.

Andersson, O., Rydell, L. (2018). The HT-BTES in Emmaboda, Sweden – Lessons learned and Further Actions. Enerstock 2018, Adana, Turkey, April 2018

Gehlin, S., Spitler, J.D., Larsson, A., Annsberg. (2018). Measured Performance of the University of Stockholm Studenthuset Ground Source Heat Pump System. Enerstock 2018, Adana, Turkey, April 2018.


Photo: Studenthuset by Jeff Spitler