Measured long-term performance data for ground source heat pump systems serving commercial, institutional and multi-family buildings are rarely reported in the literature. Energy use intensity figures are occasionally published, but as they necessarily lump the building loads and the system performance together, they are of limited usefulness in understanding real-world system performance.

Annex 52 will bridge the gap between those who see the heat pump system as a complex environment and the ground source as a black box, and those who see the ground source as a complex environment and the heat pump system as a black box.


The Annex 52 aims to survey and create a library of quality long-term measurements of GSHP system performance for commercial, institutional and multi-family buildings. All types of ground sources (rock, soil, groundwater, surface water) are included in the scope. While previous work will be surveyed, the emphasis of the annex will be on recent and current measurements. The annex also aims to refine and extend current methodology to better characterize GSHP system performance serving commercial, institutional and multi-family buildings with the full range of features shown on the market, and to provide a set of benchmarks for comparisons of such GSHP systems around the world.

Analysis procedures that help diagnose poor performance and opportunities for system performance improvements will be investigated. Multiple case studies featuring GSHP system performance measurements for systems around the world will be included and these case studies will serve as reference sets for future benchmarking.


Task 1. Long-term measurement case studies – new and previous

  • An annotated bibliography covering past GSHP system performance studies will be prepared. As part of this work, a summary of benchmarking results will be developed.
  • A report covering case studies of GSHP performance monitoring projects will be prepared. It is expected that each participant will provide at least one case study and some participants will provide more than one. As the projects will be at various stages of completion at the beginning of the annex, it is expected that the more complete projects will provide useful lessons learned and suggested improvements for the newer projects.

Task 2. Guide for instrumentation and measurement of GSHP systems

  • A consensus on necessary instrumentation and monitoring (parameters, frequency, instrument quality, etc.) will be reached by the participants.
  • A report (guideline document) on instrumentation and measurement of GSHP system performance will be published.

Task 3. Guide for analysis and reporting of GSHP system performance data

  • A consensus on key parameters and analysis procedures for GSHP system performance monitoring will be reached.
  • A report (guideline document) on analysis and evaluation reporting of GSHP system long-term performance will be published.