Comparison of the hygrothermal performance of two light-framed timber structure buildings under different operation modes

Abstract

目 的 夏热冬冷地区气候全年高湿且居民采用间歇用能辅以通风的方式调节环境, 由于建筑室内外环境条件复杂多变, 轻型木结构建筑在该区的适用性尚有待研究. 本文旨在研究用能季典型气象日及相应间歇用能工况下的室内环境及围护结构热湿传递特征, 并探究在不同条件下围护结构不同朝向及不同位置热湿传递的差异, 明确墙体冷凝霉变的关键位置, 为工程运用提供参考. 创新点 1. 建立轻型木结构建筑足尺模型, 并在墙体不同位置设置温湿度监测点进行实验与比较; 2. 以夏热冬冷地区间隙用能工况作为实验条件, 研究更加贴近真实情况. 方 法 1. 通过文献调研梳理夏热冬冷地区居民用能及通风习惯, 选择典型间歇工况作为实验条件. 2. 运用温湿度自记仪、 传感器对室内及墙体内部温湿度进行监测, 通过对比不同时刻、 位置的温湿度差异, 总结轻型木结构建筑室内环境及围护结构材料在典型工况下的热湿特征. 结 论 1. 一号建筑的总传热阻略高于二号建筑, 总传湿阻大大高于二号建筑, 其外墙对温湿度的变化具有更强的抵抗能力, 在室内外环境不理想时能较好地保持与调节室内环境; 而二号建筑在间歇用能和通风时相应较快. 2. 岩棉层两侧的材料容易出现相对湿度较高的状况, 夏季靠室内侧的石膏板具有高湿风险, 而冬季靠室外侧的定向刨花板(OSB(层具有高湿风险. Light-framed timber structure (LTS) buildings have been highly valued in recent years due to their low-carbon characteristics. However, the applicability of the building envelope is closely related to indoor and outdoor conditions. The hot summer and cold winter (HSCW) climate zone in China has high humidity and great temperature variation throughout the year, resulting in distinct outdoor environments in different seasons. The indoor environment is greatly affected by energy-consumption patterns and window-opening habits, which largely depend upon the regulation operations of occupants. All these interrelated factors lead to extremely complex boundary conditions on each side of the building envelope. Whether the structures of LTS buildings are applicable in this climate zone, therefore, needs to be carefully considered. In this study, two LTS buildings with different envelopes were established in Haining, China, situated in the HSCW climate zone, and selected as the study objects. Different operation modes were adopted to create a variety of indoor environments. Under each condition, the processes of heat and moisture transfer within the building envelopes and the indoor environment were monitored and compared. The comparison indicated that the building envelope with high moisture storage and insulation ability maintained a relatively stable indoor environment, especially when the environment changed abruptly. Conversely, if the outdoor environment was equable (e.g., relative humidity within the range of 30%–60%) or intermittent energy consumption modes were adopted, the building envelope with a low thermal inertia index and weak moisture-buffering ability performed better because it enabled a faster response of the indoor environment to air conditioning. Moreover, a high risk of moisture accumulation between the thermal insulation layer and other materials with a large water vapour transfer resistance factor was also identified, suggesting a higher requirement for the vapour insulation of the envelopes of LTS buildings.