Direct Ground Cooling Systems for Office Buildings
Doctoral thesis, 2021
This work aims to develop knowledge about comfort cooling for office buildings using DGCSs and expand upon design and operation practices for this technology. The findings presented in this work are based on experimental and simulation results. The experimental results build upon existing knowledge for operating cooling systems and substantiate new operation methods for the DGCSs. The experimental results are also used to develop and validate simulations. The simulation results facilitate investigating the short- and long-term thermal and energy performance of the DGCSs for various design circumstances.
The borehole system design is usually performed independently from the building energy system design. In view of this work’s findings, considering the whole system (borehole, control system, terminal units) can enhance the design. A sub-system’s input design requirements can be aligned with the corresponding output of other sub-systems in a comprehensive design approach.
This work demonstrates and quantifies that terminal units with slow response, such as thermally active building systems (TABS), can smooth out the daily peak heat rejection loads to the ground, resulting in shorter boreholes. Thus, the ground system can be much smaller than required for fast-response terminal units, such as active chilled beams.
This work analyses different operation practices for DGCSs. The results suggest that allowing the room temperature to rise somewhat during the “on-peak” cooling loads can reduce the ground heat rejection loads, for which shorter boreholes can be designed. If combined with precooling the space during the “off-peak” cooling loads, a further reduction in the ground loads is yielded.
This work also investigates the design and application of the DGCSs in existing office buildings. A systematic approach is provided to evaluate the influence of common renovation parameters on the design and energy performance of a DGCS. The systematic approach includes a step-by-step methodology to explain how sensitive the subsequent system design might be to the variations in the renovation parameters. Furthermore, the results quantify the potential electricity savings by using the DGCS instead of a chiller.
Ground heat exchangers
Active chilled beams
Passive ground cooling
Direct ground cooling
Ceiling cooling panels
Chalmers, Architecture and Civil Engineering, Building Services Engineering
Cooling of office buildings in cold climates using direct ground-coupled active chilled beams
Renewable Energy,; Vol. 164(2021)p. 122-132
Influence of system operation on the design and performance of a direct ground-coupled cooling system
Energy and Buildings,; Vol. 234(2021)
Control methods for a direct-ground cooling system: An experimental study on office cooling with ground-coupled ceiling cooling panels
Energy and Buildings,; Vol. 197(2019)p. 47-56
Energy Renovation Strategies for Office Buildings using Direct Ground Cooling Systems
Science and Technology for the Built Environment,; Vol. In Press(2021)
A comparative study on borehole heat exchanger size for direct ground coupled cooling systems using active chilled beams and TABS
Energy and Buildings,; Vol. 240(2021)
This work aims to develop knowledge about comfort cooling for office buildings using DGCSs and expand upon design and operation practices for this technology. The borehole system design is usually performed independently from the building energy system design. In view of this work’s findings, considering the whole system (borehole, control system, terminal units) can enhance the design. A sub-system’s input design requirements can be aligned with the corresponding output of other sub-systems in a comprehensive design approach.
Areas of Advance
Building Futures (2010-2018)
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4914
Chalmers University of Technology
Opponent: Prof. Simon Rees, School of Civil Engineering, University of Leeds, United Kingdom.