The objectives of this study were to investigate the thermally activated building system (TABS) mechanism for appropriate use of the system and to apply the proper concept of TABS for each zone by using different TABS control strategies. In order to examine the TABS mechanism, dynamic simulation with EnergyPlus was used to model the office building with TABS, because the radiant heat exchange characteristics of the TABS according to the time variable was critical. The typical control concept of TABS, self-regulation, was applied in the simulation by setting the supply water temperature as room setpoint temperature. As a result, the advantage of self-regulation can be amplified by utilizing the entire thermal mass of the TABS, which can be executed by customizing to target a specific type of load. Since the large area of the office building may comprise different loads in different zones, the TABS control according to the different zone loads were proposed. By separating the control strategy from zone to zone, the proposed control strategy improved the thermal comfort by 5%, reduced peak heating load by 10%, reduced cooling load by 36%, and decrease the total energy consumption by 13%. This study demonstrated a possible improvement on self-regulation of TABS with separate zone controls.

In this study, we propose a method for the evaluation of the thermal output of radiant heating panels by employing a modification of the currently used method, which is recommended by existing standards, using cooling plates. We aim to overcome the absence in the measurement method of the downward thermal output as well as to address the challenges in the control of the heat transfer resistance of the heat transfer layer, which arise due to the contact resistance between the layers. Using the modified method, we compare the thermal performance of three types of raised floor integrated radiant heating panels that have different filler materials for the bottom insulation of the panel. We show that the most efficient sample panel is the one that is not filled with a material; with an efficiency of 70.1%. In addition, we show that the value of the gradient of the characteristic curve calculated by the existing method ranged between 7.2% to 14.9% larger than that obtained by modified method. This difference is attributed to the heat transfer resistance of the heat transfer layer that is present in the experiments, and has a value in the interval of 0.1096 ${\mathrm{m}}^2\mathrm{K}/\mathrm{W}$ to 0.1582 ${\mathrm{m}}^2\mathrm{K}/\mathrm{W}$ . This is caused by the contact resistance between the heat transfer layer and other layers, even though the heat transfer resistance of the heat transfer layer used in the experiment is 0.0985 ${\mathrm{m}}^2\mathrm{K}/\mathrm{W}$ . The modified method proposed in this study reveals that the experimental results are not influenced by the heat transfer resistance of the heat transfer layer. We also show that our experimental results are reproducible.

The present study aims to evaluate whether downdraft can be prevented by applying a radiant floor heating system in glass curtain wall buildings. A radiant floor heating system does not directly supply heat to cold air, but does so via heat exchange with a cold airflow. Assessing whether a downdraft is prevented is, thus, necessary. For this assessment, a radiant floor heating system was applied to perimeter zones with different window types modeled using a computational fluid dynamics (CFD) simulation. The relationship between the radiant floor heating system and the windows was examined via an assessment of the resulting downdraft by considering the radiant heat exchange effect between the window and the floor. The assessment was conducted by utilizing a CFD simulation. The simulation results show that the temperature difference between the air supplied through the radiant floor heating system and the air descending along the cold surface of the window increased when the radiant floor heating system was applied to a narrow area with a high temperature. Furthermore, the airflow velocity increased with the heat exchange. The airflow re-entered the window side, and the downdraft in the occupied area exceeded the strict value specified by the standards. Conversely, if heat were applied according to the indoor thermal output by widening the radiant heat area of the radiant floor heating system, a downdraft could occur as a result of a blocking failure prior to the influx of the cold air into the occupied area caused by low surface temperatures. Therefore, applying a radiant floor heating system is advantageous in a perimeter zone without causing airflow inducement at the window side with acceptable surface temperatures.