This study presents the potential for improving energy performance by considering thermal performance degradation due to the aging of building envelopes. The U-value is a critical parameter for simulating a building's energy performance evaluation. However, because of the difficulty of in-situ measurements, many cases involve using standard or normative values for assessment. Nevertheless, considering the degradation of the external wall's insulation performance due to aging is crucial. We measured the thermal transmittance of external walls in 62 aged buildings constructed in various periods and quantitatively derived the degree of insulation performance degradation by comparing it with the legal standards at the time of construction. Moreover, to analyze the problems caused by neglecting the U-value deterioration in evaluating the energy-saving potential through retrofitting, a case study was conducted on 70 aged buildings where actual retrofit projects were implemented. We compared the cases by applying both legal thermal transmittance standards and corrected values based on actual measurements to the sites' pre-retrofit energy simulation models. The measurements showed that the aged buildings had an average insulation performance degradation of 49.69 % compared to the legal standards at the time of approval. Simply using the legal standard for the external wall's thermal transmittance underestimated the energy savings by 16.73 %. Furthermore, the study confirmed that correcting the U-value based on actual measurement data is essential for accurately evaluating the retrofit effect on aged buildings.

中文翻译：

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考虑外墙保温退化的老旧建筑改造节能潜力估算


这项研究通过考虑由于建筑围护结构老化导致的热性能下降，提出了提高能源性能的潜力。 U值是模拟建筑物能源性能评估的关键参数。然而，由于现场测量的困难，许多情况下需要使用标准或规范值进行评估。尽管如此，考虑到老化导致的外墙保温性能下降至关重要。我们测量了62座不同时期建造的老旧建筑的外墙热传导率，并与施工时的法定标准进行比较，定量得出保温性能下降的程度。此外，为了分析在评价改造节能潜力时忽略U值恶化带来的问题，对70栋实际实施改造的老旧建筑进行了案例研究。我们通过应用法定的热传导率标准和基于实际测量的修正值来对现场改造前的能源模拟模型进行比较。测量结果显示，与批准时的法定标准相比，老化建筑的隔热性能平均下降了49.69%。单纯使用外墙传热系数的法定标准低估了16.73%的节能效果。此外，研究还证实，根据实测数据对U值进行修正对于准确评估老化建筑的改造效果至关重要。