Analysis of the Applicability of Non-Destructive Techniques to Determine In Situ Thermal Transmittance in Passive House Façades

• Main Authors: Blanca Tejedor, Kàtia Gaspar, Miquel Casals, Marta Gangolells
• Format: Article
• Language: English
• Published: MDPI AG 2020-11-01
• Series: Applied Sciences
• Subjects: Nearly Zero Energy Buildings (NZEB); passive house (PH); heat flux meter (<i>HFM</i>); quantitative infrared thermography (<i>QIRT</i>); building thermal performance; U-value
• Online Access: https://www.mdpi.com/2076-3417/10/23/8337

Within the European framework, the passive house has become an essential constructive solution in terms of building efficiency and CO₂ reduction. However, the main approaches have been focused on post-occupancy surveys, measurements of actual energy consumption, life-cycle analyses in dynamic conditions, using simulation, and the estimation of the thermal comfort. Few studies have assessed the in situ performance of the building fabric of passive houses. Hence, this paper explores the applicability of non-destructive techniques—heat flux meter (<i>HFM</i>) and quantitative infrared thermography (<i>QIRT</i>)—for assessing the gap between the predicted and actual thermal transmittance of passive house façades under steady-state conditions in the Mediterranean climate. Firstly, the suitability of in situ non-destructive techniques was checked in an experimental mock-up, and, subsequently, a detached house was tested in the real built environment. The findings revealed that both Non-Destructive Testing (NDT) techniques allow for the quantification of the gap between the design and the actual façades U-value of a new passive house before its operational stage. <i>QIRT</i> was faster than the <i>HFM</i> technique, although the latter was more accurate. The results will help practitioners to choose the most appropriate method based on environmental conditions, execution of the method, and data analysis.