Case-study of thermo active building systems in Japanese climate

Thermo active building systems (TABS) have been applied in office buildings as a promising energy efficient solution in many European countries. The utilization of building thermal mass helps to provide high quality thermal environments with less energy consumption. However, the concept of TABS is entirely new in Japan. This paper introduces and evaluates TABS under Tokyo weather conditions to clarify the potential of use TABS in Japan. Cooling capacity of thermo active building systems used in an office building was evaluated by means of dynamic simulations. Two central rooms of the office were selected for the analysis. Six water control strategies were studied and two of those were found reasonable and suitable for TABS use in Tokyo. These two strategies are: free-cooling using underground heat exchanger combined with TABS and free-cooling with desiccant dehumidification system. For these two cases, the operative temperature was between 22-27 °C during 97∼99% of the occupation time. The operative temperature drift was less than 4 °C per day. The pump running time was 7 hours per day and the cooling power of the TABS was 36 W/m2 floor area. For those free-cooling cases, the average supply water temperature was 20 °C, which shows that free-cooling is achievable using underground heat exchangers even considering the temperature increase of the ground during cooling season

Field evaluation of performance of radiant heating/cooling ceiling panel system

As in many other countries in the world, Japan has witnessed an increased focus on low-energy buildings. For testing different engineering solutions for energy-efficient buildings, a low-energy building was built at the University of Tokyo as an experimental pilot project. In this building, a radiant heating/cooling ceiling panel system is used. However, no standard exists for the in situ performance evaluation of radiant heating/cooling ceiling systems; furthermore, no published database is available for comparison. Thus, this study aims to not only clarify the system performance but also to share our experience and our results for them to serve as a reference for other similar projects. Here, the system performance in relation to its heating/cooling capacity and thermal comfort has been evaluated. The heat transfer coefficient from water to room was 3.7 W/(m2 K) and 4.8 W/(m2 K) for heating and cooling cases, respectively. The upward heat flux from the panels was found to be as large as 30–40% of the water heating/cooling capacity; this would translate into heat loss in certain operating modes. Several proposals for reducing the upward heat flux were discussed. The measurements also showed that a category B thermal environment was obtained using the radiant ceiling heating/cooling system

Field evaluation of performance of radiant heating/cooling ceiling panel system

As in many other countries in the world, Japan has witnessed an increased focus on low-energy buildings. For testing different engineering solutions for energy-efficient buildings, a low-energy building was built at the University of Tokyo as an experimental pilot project. In this building, a radiant heating/cooling ceiling panel system is used. However, no standard exists for the in situ performance evaluation of radiant heating/cooling ceiling systems; furthermore, no published database is available for comparison. Thus, this study aims to not only clarify the system performance but also to share our experience and our results for them to serve as a reference for other similar projects. Here, the system performance in relation to its heating/cooling capacity and thermal comfort has been evaluated. The heat transfer coefficient from water to room was 3.7 W/(m2 K) and 4.8 W/(m2 K) for heating and cooling cases, respectively. The upward heat flux from the panels was found to be as large as 30–40% of the water heating/cooling capacity; this would translate into heat loss in certain operating modes. Several proposals for reducing the upward heat flux were discussed. The measurements also showed that a category B thermal environment was obtained using the radiant ceiling heating/cooling system