Interaction of GEOTABS and secondary heating and cooling systems in hybridGEOTABS buildings: towards a sizing methodology

Abstract

GEOTABS, a combination of TABS with a geothermal heat pump, is a promising heating and cooling system for decreasing greenhouse gas emissions in the building sector. However, TABS has a time delay when transferring energy from the pipes to the room. So, when the heat demand changes fast, TABS cannot properly compensate the heat demand. In order to solve this problem and maintain thermal comfort in the room, the concept of hybridGEOTABS proposes using a fast secondary system to assist the TABS. Yet, there is no integrated method for sizing both systems in a hybridGEOTABS building, considering the interaction between the secondary system and GEOTABS. This study will provide an integrated sizing methodology for hybridGEOTABS buildings. To that purpose, in this paper the interaction between the secondary system and TABS is investigated for two different scenarios by using a preference factor between the TABS and the secondary system. The methodology starts from heat demand curves, an analytic model for TABS, and optimal control principles for TABS to minimize the total energy use while providing thermal comfort. Finally, the method is used for 4 case studies in different scenarios with different secondary systems. Preliminary results of this research indicate that the secondary system type doesn’t have effect on the strategy of sizing. Therefore, designer can decide about secondary system type with investment and operating cost analysis.

Developing a simplified methodology for simulating energy performance of buildings with thermally activated building systems

“…The secondary system power (Q ̇SecSys ) is injected to the zone capacitor directly to rapidly provide thermal comfort if TABS cannot achieve that. Sharifi et al (2019aSharifi et al ( , 2019b) elaborated the interactions between TABS and the secondary and the key factors to be considered even in a simplified model.…”

“…Steady sate calculation methods result in an overestimation of the HVAC components size (Sharifi et al, 2020). Therefore, the dynamic behaviour of the system has to be simulated when sizing the primary and the secondary system to take their interaction into account (Sharifi, 2019b). An optimal control such as model predictive control (MPC) can optimise the interaction of both systems in providing thermal comfort (Sourbron, 2012).…”