Confronto tra valori sperimentali e teorici di sfasamento e attenuazione termica per un edificio leggero con struttura intelaiata in acciaio = A Comparison between Experimental and Theoretical Values of Time Shift and Decrement Factor in a Lightweight Steel-Framed Building

The in-situ thermal behavior of building components often deviates from what is expected at the design stage. On the other hand, with the rise of average outdoor temperatures in summer due to climate change, it becomes more and more relevant to understand how and if the building envelope can effectively decrease and shift the summer heat wave. From a theoretical point of view, the decrement factor and the time shift have been widely discussed, but few experimental investigations have been undertaken. In this research context, the paper presents a comparison analysis between the predicted and monitored performance of two different types of lightweight steel-framed walls for a building located in Barnaul (RU). In particular, the study concerns the response of the walls in terms of thermal lag and decrement factor, during the hot season. The results show a remarkable difference between the expected and actual values, and underline how in an uncontrolled environment many variables may affect the final measured indoor environmental quality. The surrounding environmental conditions, the assembly operations of the specific component, but also the way in which the monitoring data is collected and processed can all contributed to a 50% reduction in wall performance. As a result, the research emphasizes the need for an appropriate and common evaluation and calculation methodology, which is lacking in current standards, that allows the differences between “as-built” and “as-designed” to be considered right from the beginning of the design process.