Co-simulation of building energy and geothermal systems: A review

Integration of geothermal systems into buildings is imperative for a sustainable energy transition. Coupled
simulation of building energy systems and geothermal technologies can support reliable and efficient
geothermal-based system design, while ensuring thermal comfort inside the building. While co-simulation has
been widely applied, a comprehensive review of existing approaches and applications is still lacking. This study,
therefore, reviews co-simulation of building energy and geothermal systems covering modeling techniques,
coupling approaches, software options, as well as existing case studies. A total of 141 co-simulation studies were
identified, mostly conducted using one single software such as TRNSYS (58 %), EnergyPlus (9 %), IDA ICE (8 %)
and Modelica (5 %) by incorporating simplified semi-analytical geothermal models. Only few studies coupled a
building energy tool with a high-fidelity physical model of the subsurface for co-simulation (< 10 %). Studies
mainly focused on borehole heat exchangers (BHE) (65 %), followed by borehole thermal energy storage (BTES)
(19 %), ground heat exchangers (GHE) (8 %), aquifer thermal energy storage (ATES) (3 %) and energy piles (EP)
... mehr
(2 %). Over 80 % of research investigated residential, commercial and institutional buildings, largely for heating
applications. Co-simulation revealed high potential of geothermal systems in buildings, with COP of 4 ± 1,
discomfort times of 6 % ± 4 %, payback period of 14 ± 9 years, and CO2 savings of 40 % ± 27 %. The literature
review showed an evolution from early feasibility analyses to detailed physics co-simulation and hybrid
geothermal energy systems. Several opportunities are highlighted for future research in the field regarding
software coupling, geothermal model validation and system design. Specifically, creating a co-simulation
framework for optimal design of building integrated geothermal systems is the key opportunity for advancing
geothermal technology application.