パッシブクーリング技術の複合による冷涼な半屋外空間の形成手法に関する研究

In order to reduce heat in urban environments, the Japanese government has been enforcing mitigation and adaptation policies; however, due to insufficient design guidelines, it is still difficult to form a cool environment.The purpose of this study is to propose an evaluation index and design guideline for the formation of cool spots in semi-outdoor spaces using passive cooling methods, and to confirm the total cooling effect of the designed space by means of air temperature, MRT and sensible temperature. In order to form a cool spot in semi-outdoor space, it is important to utilize natural ventilation at windy condition, but also to decline radiative temperature and generate cool air at breeze condition. Therefore, we focused on evaporative cooling methods that are applied to vertical plane, and proposed a cooling evaluation index based on the ambient wet bulb temperature, with βTs, βTa_lee and βTa_for as the cooling efficiencies of the surface temperature, cool air on leeward and forward side of the passive cooling techniques, respectively. From the measurements of the individual methods, we quantified βTs, βTa_lee and βTa_for of trees, a Passive cooling louver, and lava walls under watering condition, and the values for βTs with these methods were found to be 0.12, 0.55, and 0.76, respectively, and βTa_lee at a wind velocity >0.5 m/s were found to be 0.11, 0.17, and 0.36, respectively.A “Cool terrace” was designed for a semi-outdoor space with shade on the ceiling and water retentive blocks on the floor, on the basis of βTa (average βTa_lee of all the vertical planes in the space) to achieve an air temperature decline by more than 1°C and MRT equivalent or lower than the ambient air temperature. The extent of evaporative cooling methods that needs to be applied was calculated based on the required βTa, and by taking into account the dominant wind direction of the area, the evaporative cooling methods were allocated as a “Cool terrace”. The measurement result of the Cool terrace showed an air temperature decline of 1.5 to 2.7 °C, and an MRT equivalent to the representative air temperature at breeze. Moreover, the SET* (standard new effective temperature) of the Cool terrace was at most 6 °C lower compared to the SET* of the adjacent deck terrace, when the solar radiation was large, and was on an average 1 °C lower, when it was cloudy. The contribution of each environmental element to the reduction in SET* was analyzed, and when the difference in SET*'s w