基于热湿耦合传递的上海超低能耗建筑外墙湿风险分析

Wet Risk Analysis on the External Walls of Ultra-low Energy Buildings in Shanghai Based on Coupled Heat and Moisture Transfer

根据上海地区超低能耗建筑标准,提高外墙的热工性能对降低建筑能耗有重要意义。然而,建筑显热负荷降低的同时,建筑湿负荷及其影响成为建筑环境控制与能耗降低的关键。因此,需要重新审视建筑围护结构的湿传递影响,尤其是上海地区,湿热环境对超低能耗建筑的影响不容忽视,热湿耦合的墙体湿传递特征更加显著。以上海地区保温外墙为研究对象,建立多层墙体的热湿耦合传递模型,对比分析采暖期和空调期内不同保温层位置和厚度设计对墙体热湿性能的影响。结果表明,外保温的保温隔热效果最好,冬季冷凝风险最低,内保温外墙夏季具有最低的湿风险,而中间保温外墙在冬夏两季都具有较稳定的湿度分布。保温层厚度的增加可以在一定程度上降低湿风险,尤其在湿度值较高的情况下。空气间层的设置整体上对调整温度和湿度分布的作用不显著,其主要作用在于隔绝高湿部位的液态湿分传递。

According to Shanghai’s ultra-low energy building standards,improving the thermal performance of external walls is critical to lowering building energy consumption.However,while the sensible heat load of the building is reduced,the moisture load of the building and its effects become key to the control of the building environment and the reduction of energy consumption.Therefore,the impact of moisture transfer in the building envelope must be reconsidered,especially in Shanghai,where the impact of the hot and humid environment on ultra-low energy buildings cannot be ignored,and the moisture transfer characteristics of the walls with coupled heat and moisture transfer are even more critical.Using insulated external walls in Shanghai as the research object,a coupled heat and moisture transfer model for multi-layer walls is developed to compare and analyze the effects of different insulation positions and thickness designs on the heat and moisture performance of the walls during the heating and air-conditioning periods.The results show that external insulation provides the best thermal insulation,and has the lowest risk of condensation in winter,external walls with internal insulation have the lowest condensation risk in summer,and external walls with intermediate insulation have a more stable humidity distribution in both winter and summer.The increased thickness of the insulation reduces the risk of moisture to some extent,especially at high humidity levels.The installation of the air layer has a negligible effect on the adjustment of temperature and humidity distribution,its primary function being to isolate water transfer from high humidity areas.