Impact of Stationary and Dynamic Conditions on the U-Value Measurements of Heavy-Multi Leaf Walls by Quantitative IRT

Blanca Tejedor,Eva Barreira,Vasco Peixoto De Freitas,Umberto Berardi,Katarzyna Nowak-Dzieszko,Tomasz Kisilewicz

doi:10.3390/en13246611

Abstract

Infrared thermography (IRT) has become a commonly applied non-destructive testing method for assessing building envelopes. Like any diagnosis tool, IRT requires an appropriate experience and principle understanding, mainly when the method is used for quantitative analyses. The challenges of the IRT often deal with the dynamic properties of building partitions. Climatic conditions have a certain variability, and the accumulated energy storage in the building components can affect their temperature as well as the calculated thermal performance. This paper aims to analyze how stationary and dynamic regimes of a quantitative IRT test could impact the measured thermal transmittance of heavy multi-leaf walls. Investigation in two European countries with different climatic conditions are reported. In this way, it is discussed which boundary conditions should be guaranteed to provide reliable information about a building envelope using quantitative IRT. In order to check the quality of the measurements, the heat flux meter (HFM) method was also implemented, following the ISO 9869. The research revealed that it could be possible to use short-lasting tests in the climatic conditions of Southern Europe, while long-term tests should be implemented in Northern European countries where climatic conditions are less regular.

Highlights

The increment of building energy consumption and the respective sensibility of police makers to energy conservation are leading the request for a proper design and accurate assessment of the construction elements [1]
A period with heavy conduct measurements in existing buildings by non-destructive testing techniques (NDT) methods: (i) tests should be conducted on early cloud cover was accepted for further analysis
Despite of a slight pulsation of the external temperature and practically constant internal temperature, in-prior [1]; (iv) the metering section of the Heat Flux Method (HFM) should be defined by a qualitative inspection prior the heat flux through the façade described regular cyclical changes

Summary

Introduction

The increment of building energy consumption and the respective sensibility of police makers to energy conservation are leading the request for a proper design and accurate assessment of the construction elements [1]. The most popular non-invasive technique for assessing the thermal transmittance of building elements is the HFM method, based on the standard ISO 9869–1:2014 [8]. This regulation establishes that the test duration should be an integer multiple of 24 h. The same standard highlights that the test shall be stopped when: (i) the deviation between the R-value at the end of the test and the R-value obtained

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Conclusion