Model Predictive Control (MPC) predictive’s nature makes it attractive for controlling high-capacity structures such as thermally activated building systems (TABS). Using weather predictions in the order of days, the system is able to react in advance to changes in the building heating and cooling needs. However, this prediction horizon window may be sub-optimal when hybrid geothermal systems are used, since the ground dynamics are in the order of months and even years. This paper proposes a methodology that includes a shadow-cost in the objective function to take into account the long-term effects that appear in the borefield. The shadow-cost is computed for a given long-term horizon that is discretized over time using predictions of the building heating and cooling needs. The methodology is applied to a case with only heating and active regeneration of the ground thermal balance. Results show that the formulation with the shadow cost is able to optimally use the active regeneration, reducing the overall operational costs at the expenses of an increased computational time. The effects of the shadow cost long-term horizon and the predictions accuracy are also investigated.

Fluid temperature predictions of geothermal borefields usually involve temporal superposition of its characteristic g-function, using load aggregation schemes to reduce computational times. Assuming that the ground has linear properties, it can be modelled as a linear state-space system where the states are the aggregated loads. However, the application and accuracy of these models is compromised when the borefield is already operating and its load history is not registered or there are gaps in the data. This paper assesses the performance of state observers to estimate the borefield load history to obtain accurate fluid predictions. Results show that both Time-Varying Kalman Filter (TVKF) and Moving Horizon Estimator (MHE) provide predictions with average and maximum errors below 0.1 ${}^{\circ }$C and 1 ${}^{\circ }$C, respectively. MHE outperforms TVKF in terms of n-step ahead output predictions and load history profile estimates at the expense of about five times more computational time.

This report provides a technical description of the hybridGEOTABS case-study and demonstration buildings: Infrax/Fluvius office building (Belgium), Ter Potterie elderly home (Belgium), Libeznice school (Czech Republic), Haus M (Switzerland), Solarwind office building (Luxembourg). The description includes an overview of the building design, the HVAC-design (incl. hydraulic schemes) and the HVAC controllers (RBC and MPC).

Current and best practices for hybridGEOTABS design and control around Europe are described in this report. It provides an overview of the design of a hybridGEOTABS building and the core modules, and an overview of the latest developments for controlling integrated building systems using MPC. The report provides an overview of the state-of-the-art hybridGEOTABS design and control during the hybridGEOTABS project and allows to understand the issues various stakeholders are facing, for which solutions are developed in the hybridGEOTABS project.