Numerical investigation on urban warming and energy consumption in Tohoku region based on whole year analysis of urban climate

本研究项目由两部分组成。第一部分开发了城市气候全年分析模拟系统。通过与实测数据的比较，验证了数值计算结果的准确性。其次，利用夏季和冬季的数值结果，在分析城市空间大气部分热平衡的基础上，结合夏季海风和冬季西北风降温区域的“热平衡图”，探讨仙台市内城市气候的区域特征。在此基础上，根据仙台市内各区域的区域特征，选择相应的热岛效应对策。在研究的后半部分，利用瞬态能源系统模拟工具“TRNSYS”，结合中尺度气候数值分析、建筑周边小气候CFD方法、辐射计算和热负荷计算，提出了一种新的模拟方法来评估交叉通风被动冷却效应的空间分布。在仙台市内的三个地区（内陆地区，仙台市中部，沿海地区），对住宅建筑的冷负荷进行了量化。其次，绘制了“冷负荷图”，详细说明了仙台市内冷负荷的空间分布情况以及通过交叉通风减少的冷负荷。研究发现，在仙台沿海地区，交叉通风的影响显著较大。合理利用交叉通风的被动冷却效果，可使空调负荷降低50% ~ 90%。

This research project is composed of two parts. In the first part, the simulation system for the whole year analysis of urban climate was developed. The accuracy of numerical results was examined by comparing its results with measured data. Next, the regional characteristics of urban climate inside Sendai was investigated based on the analysis of heat balance in the atmospheric part in urban space using the numerical results of the summer and winter seasons, and "heat balance map" that illustrated the areas where air temperature was decreased by sea breeze in summer and a seasonal wind from north-west in winter. Based on this map, the appropriate countermeasures against heat island effects were selected according to the regional characteristics of each region inside Sendai.In the latter part of this study, a new simulation method, which combined numerical analysis of mesoscale climate, CFD method for microclimate around building, radiation computations, and heating load calculation using the transient energy system simulation tool "TRNSYS", was developed to evaluate the spatial distributions of passive cooling effects due to the cross-ventilation. In three regions inside Sendai (Nenoshiroishi (inland area), central part of Sendai, Arai (coastal area), cooling loads for residential buildings were quantified. Next, "cooling load maps" that illustrated the detailed spatial distribution of cooling load inside Sendai and the reduction of cooling load by cross-ventilation were drawn. It was found that the effect of cross-ventilation was significantly large in the coastal areas of Sendai. The cooling load could be reduced by 50%〜90% by appropriately utilizing the passive cooling effects of cross-ventilation.