Experimental and modeling investigation of thermally activated building systems integrated with ground source heat pump systems

[Display omitted] •The performance of a thermally activated building system was experimentally studied.•A ground source heat pump system was integrated to provide heating and cooling.•The optimal operating condition was identified to efficiently operate the integrated system.•A 5R3C network model was developed for further performance investigation. Thermally activated building systems (TABSs) offer promising potential for enhancing energy efficiency and indoor thermal comfort in the building sector. The existing studies related to TABSs are mainly limited to simulations and lab-based experiments and studies on experimental tests in real buildings with integrated TABS and ground source heat pump systems are limited. This paper presents an experimental investigation and performance evaluation of a thermally activated building system integrated with a ground source heat pump (TABS-GSHP) system implemented in a net-zero energy office building. A matrix of experiments in the heating mode was designed and analyzed using the Taguchi method to find the optimal operating conditions to improve the operating efficiency of the TABS-GSHP system. A dynamic thermal resistance–capacitance (RC) network model for the floor TABS was also developed to explore additional conditions to overcome experimental limitations. The experimental results showed that the TABS-GSHP system studied can achieve a COP of 5.73 based on the optimal settings for the ground loop differential pressure set-point, slab loop differential pressure set-point, and slab supply water temperature set-point, determined through Taguchi method analysis. The validation of the 5R3C model using the experimental data demonstrated good accuracy in predicting indoor air temperature under two different slab loop differential pressures of 100 kPa and 70 kPa with the maximum relative error of 0.97 % and 1.48 %, respectively. A total of 24 simulation cases based on two different differential pressures in the TABS loop, which were developed considering different operating schedules and slab supply water temperatures, were further used to investigate the indoor thermal performance. On three consecutive winter days, the TABS maintained an indoor air temperature at 20 °C or above for 83.78 % of the occupied period when the supply water temperature was 38 °C and the system was operated from midnight to 5 pm with the slab loop differential pressure of 100 kPa. The results can be used to facilitate the development of optimal c