Abstract In the present work, three different methodologies to determine the equivalent thermal diffusivity of an opaque wall, part of a building envelope, were compared. The thermal behaviour of a typical wall of a recently built building has been recorded; the internal and external temperatures were measured for one month, during day and night, with one acquisition every 10 min. The experimental data were processed by means of three analytical models, getting as a result the effective thermal diffusivity of the wall. The first model used is the semi-infinite region, the second a symmetric slab with periodic surface temperatures and the third the ISO 13786:2007 rule. All models produce different values if thermal diffusivity is evaluated from the ratio of the external and internal amplitudes or from their phase shifts. For the first model the α values obtained are respectively (1.512·± 0.016)·10−6 m2 s−1 and (2.813 ± 0.004)·10−6 m2 s−1; for the second (1.741 ± 0.150)·10−6 m2 s−1 and (2.603 ± 0.007)·10−6 m2 s−1, and (1.880 ± 0.017PCNM)·10−6 m2 s−1 and (2.168 ± 0.003)·10−6 m2 s−1 for the third. This difference is likely due to the lack of correspondence of the wall models to its real structure. When a non-linear regression is applied to data, a unique value is obtained, intermediate between the two, i.e. (2.544 ± 0.021)·10−6 m2 s−1 (first model), (1.854 ± 0.010)·10−6 m2 s−1 (second model) and (1.988 ± 0.012)·10−6 m2 s−1 (third model). Both the difference between the two values of thermal diffusivity and the root mean square obtained from the nonlinear-least square regression asses that the best results come from the application of the ISO 13786 rule.

中文翻译：

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评估动态条件下建筑墙体等效热扩散率的不同方法的比较

摘要 在目前的工作中，对确定不透明墙（建筑围护结构的一部分）的等效热扩散率的三种不同方法进行了比较。记录了最近建造的建筑物的典型墙壁的热行为；内部和外部温度测量了一个月，白天和黑夜，每 10 分钟采集一次。实验数据通过三个分析模型进行处理，得到墙体的有效热扩散系数。使用的第一个模型是半无限区域，第二个是具有周期性表面温度的对称板，第三个是 ISO 13786:2007 规则。如果根据外部和内部幅度之比或其相移来评估热扩散率，则所有模型都会产生不同的值。对于第一个模型，获得的 α 值分别为 (1.512·± 0.016)·10−6 m2 s−1 和 (2.813 ± 0.004)·10−6 m2 s−1；对于第二个 (1.741 ± 0.150)·10−6 m2 s−1 和 (2.603 ± 0.007)·10−6 m2 s−1，和 (1.880 ± 0.017PCNM)·10−6 m2 s−1 和 (2.168 ± 0.003)·10−6 m2 s−1 第三。这种差异可能是由于墙壁模型与其真实结构缺乏对应关系。当对数据应用非线性回归时，会得到一个介于两者之间的唯一值，即 (2.544 ± 0.021)·10−6 m2 s−1（第一个模型），(1.854 ± 0.010)·10−6 m2 s−1（第二个模型）和 (1.988 ± 0.012)·10−6 m2 s−1（第三个模型）。两个热扩散率值之间的差异和从非线性最小二乘回归获得的均方根都表明，最佳结果来自 ISO 13786 规则的应用。