Control methods for a direct-ground cooling system: An experimental study on office cooling with ground-coupled ceiling cooling panels

Research output: Contribution to journalArticle


This article experimentally investigates the performance of two control methods (the supply water temperature method and the water flow control method)for a direct-ground cooling system. The control methods were implemented through three types of indoor feedback controllers: 1)an on/off controller, 2)an on/off controller with a deadband and 3)P controller. The performances of the control methods were evaluated regarding room temperature stability and pump energy use. Ceiling cooling panels were employed to keep the test room air temperature at 25.0 °C under periodic heat gain conditions. The cooling system used a ground heat exchanger with a U-pipe in an 80-meter-deep borehole as a cooling source. The findings show that room air temperature was maintained close to the set-point with both control methods, but it was more stable with the temperature control method. In addition, condensation risk was easily preventable with the temperature control method. A parametric study showed that pump energy use when using two-position controllers could be as low as when using modulating controllers if the on-state flow rate of the circulating pump is selected in relation to the ground temperature and heat transfer characteristics of the heat exchanger.


  • Taha Arghand
  • Saqib Javed
  • Anders Trüschel
  • Jan Olof Dalenbäck
External organisations
  • Chalmers University of Technology
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Building Technologies


  • Control methods, Controller, Direct-ground cooling, Energy performance, High-temperature cooling, Radiant ceiling panel
Original languageEnglish
Pages (from-to)47-56
Number of pages10
JournalEnergy and Buildings
Publication statusPublished - 2019 Aug 15
Publication categoryResearch
Externally publishedYes