Abstract Internal insulation of masonry walls may significantly increase the decay risk of embedded wooden beams due to lower temperature and consequently lower drying potential in retrofitted existing walls. Since high moisture contents will affect performance and service life of wood, the assessment of moisture-related damage risks in wooden beam-ends in internally insulated masonry walls is particularly relevant to heritage buildings. The proper selection of indoor and outdoor materials and the addition of an embedded heating source offer means of decreasing this risk. Numerical studies of hygrothermal performance of wooden beam-ends support risk assessment but traditionally this has been performed with 2D models. Therefore, in order to assess whether a 2D numerical model can represent accurately the 3D hygrothermal behavior of wooden beam-ends, the difference between 2D and 3D model results of the hygrothermal performance of wooden beam-ends embedded in internally insulated masonry wall is analysed for a northern continental climate. Given the small differences in relative humidity, temperature and mould index between the 2D and 3D models, it is suitable to replace 3D models with 2D ones for predicting the risk of moisture-related problems in the wood beam-end when studying the impact of different envelope components. However, for evaluating the effect of active heating on wooden beam-end performance, it is found that a 3D hygrothermal model should be used. In this case, a 2D model cannot accurately model heating locally at the beam-end resulting in an over prediction of temperature and thus in an underprediction of the moisture damage risk.

中文翻译：

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使用 2D 和 3D 模型评估嵌入内部绝缘砌体墙的木梁的潮湿风险

摘要 砌体墙的内保温可能会显着增加嵌入式木梁的腐烂风险，因为温度较低，从而降低了改造现有墙体的干燥潜力。由于高水分含量会影响木材的性能和使用寿命，因此评估内部隔热砖石墙木梁端与水分相关的损坏风险与遗产建筑特别相关。正确选择室内和室外材料并添加嵌入式热源可以降低这种风险。木梁端部湿热性能的数值研究支持风险评估，但传统上这是使用 2D 模型进行的。因此，为了评估 2D 数值模型是否可以准确地表示木梁端的 3D 湿热行为，针对北部大陆性气候，分析了嵌入内部隔热砖石墙的木梁端部的湿热性能的 2D 和 3D 模型结果之间的差异。鉴于 2D 和 3D 模型之间的相对湿度、温度和霉菌指数差异很小，在研究不同的影响时，适合用 2D 模型代替 3D 模型来预测木梁端部与水分相关问题的风险。信封组件。然而，为了评估主动加热对木梁端部性能的影响，发现应该使用 3D 湿热模型。在这种情况下，2D 模型无法准确地模拟梁端的局部加热，从而导致对温度的过度预测，从而导致对湿损风险的预测不足。