Case-study of Thermo Active Building Systems in Japanese Climate

Abstract

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 7hours per day and the cooling power of the TABS was 36W/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.