A comparison between thermographic and flow-meter methods for the evaluation of thermal transmittance of different wall constructions

Nardi, Iole; Ambrosini, Dario; Rubeis, Tullio de; Сфарра, Стефано; Perilli, Stefano; Pasqualoni, Giovanni

doi:10.1088/1742-6596/655/1/012007

Cited by 44 publications

(44 citation statements)

References 21 publications

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“…In order to determine the qTB and the Ψ-value, two additional specimens without thermal bridging were tested in the hot box, a plain panel 130mm thick (Specimen 4) and plain panel 155mm thick (Specimen 5) with the results presented in the Table 3. Having those results, qTB and Ψ can be obtained as the difference between the heat flow rates of specimens with thermal bridges and the heat flow rates of the plain specimens, using the Equations (24) and (25), respectively. Because of different specimen thicknesses, Specimen 1 is examined with Specimen 4 whereas Specimens 2 and 3 are compared with Specimen 5:…”

Section: Calorimetric Hot Box Device Tests and Resultsmentioning

confidence: 99%

“…The authors deemed these differences as acceptable for an in-situ method. The same authors in a further study [25] obtained the U-value of walls of three different existing buildings under real environmental conditions. Good agreement between the U-value obtained by HFM and the ITT was found for walls of a historical stone building (2.6%) and of a concrete structure (1.3%), whereas, for a light-weight wall made of cementwood brick and insulated internally, a discrepancy of 47.6% was recorded.…”

Section: Methods Of Assessing the U-valuementioning

confidence: 99%

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Infrared thermography technique as an in-situ method of assessing heat loss through thermal bridging

O’Grady

Lechowska

Harte

2017

Energy and Buildings

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A key aspect in assessing the thermal standard of building envelopes is the quantification of the heat loss though thermal bridging, which can be expressed in terms of the linear thermal transmittance Ψ. Values of Ψ may be obtained from tabulated values for standard building details, from numerical modelling or from measurement. Where the internal structure of the building envelope is unknown, which is very often the case, measurement is the only option. This study shows how the infrared thermography technique (ITT) can be used as a non-invasive and easy-to-use method to provide quantitative measures of the actual thermal bridging performance. The novelty of this approach includes evaluation of the actual heat flow rate caused by thermal bridge qTB and Ψ-value by means of the ITT solely, without any supporting methods. Another important aspect of the methodology is that it accounts for the correlation between the surface temperature and the convective and radiative heat transfer coefficients. Values for these coefficients are assessed for the whole range of the surface temperatures recorded on the thermogram resulting in improve accuracy. The qTB and Ψ-value calculated using the presented methodology fully mirrors the real thermal performance of the thermal bridge. The methodology has been tested under laboratory conditions in a steady state in a hot box with excellent agreement.

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Section: Calorimetric Hot Box Device Tests and Resultsmentioning

confidence: 99%

Section: Methods Of Assessing the U-valuementioning

confidence: 99%

Infrared thermography technique as an in-situ method of assessing heat loss through thermal bridging

O’Grady

Lechowska

Harte

2017

Energy and Buildings

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“…For a well-insulated wall, they reported that the percentage deviations of the in situ U-value measured by the IRT method with respect to calculations and the HFM method ranged from 16% to 28% and from 2% to 37%, respectively [21]. They also reported three case studies [22], and the differences between the IRT and HFM results ranged between 1% and 47% for the three cases. Danielski and Fröling [4] reported a discrepancy of 4% for small wall areas and 11% for large wall areas between the U-values of a massive wooden wall measured by both the IRT and HFM methods.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, this method has been widely applied in building diagnostics for qualitative evaluation to detect heat losses, air leakages, thermal bridges, sources of moisture, missing materials, and defects in insulation materials [12][13][14][15][16]. Furthermore, several researchers have recently studied the quantitative IRT method as an alternative approach to the in situ U-value measurement of the building envelope because it is both rapid and non-invasive [4,[17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

“…Dall'O' et al [20] reported that the percentage absolute deviation between the theoretical and measured U-values is acceptable, being within 40-45% for solid-mass buildings; however, this deviation was high (more than 50%) for well-insulated walls. Nardi et al [21,22] studied the quantitative IRT method for measuring the in situ U-values of the building envelope. For a well-insulated wall, they reported that the percentage deviations of the in situ U-value measured by the IRT method with respect to calculations and the HFM method ranged from 16% to 28% and from 2% to 37%, respectively [21].…”

Section: Introductionmentioning

confidence: 99%

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Comparison of Various Analysis Methods Based on Heat Flowmeters and Infrared Thermography Measurements for the Evaluation of the In Situ Thermal Transmittance of Opaque Exterior Walls

Choi

Ko²

2017

Energies

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There are several methods to obtain the in situ thermal transmittance value (U-value) of building envelopes from on-site data, including the three approaches of the progressive average method, average method considering the thermal storage effect, and dynamic method for deriving the U-value from heat flowmeter (HFM) measurements and the four methods with different formulas to analyze infrared thermography (IRT) measurement data. Since each of these methods considers different parameters and the non-steady characteristics of the heat transfer in building walls in their own way, discrepancies may occur among the obtained results. This study evaluates and compares the in situ U-values by using various methods of analyzing HFM and IRT measurement data. Further, by investigating buildings with similar materials and identical stratigraphies, but with different construction years, we analyze the discrepancy between the designed and measured values caused by material deterioration and evaluate the errors according to the analysis method. The percentage deviation between the U-values obtained by the three methods from the HFM data is found to be satisfactory, being within 10%. When compared with the results of the progressive average method, the deviations for the four different IRT-measurement-based methods vary greatly, being in the range of 6-43%.

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Temperature-Based Approach for In Situ Evaluation of Thermal Transmittance of Building Walls

Domazetović

Krstić

2022

Lecture Notes in Civil Engineering

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A comparison between thermographic and flow-meter methods for the evaluation of thermal transmittance of different wall constructions

Cited by 44 publications

References 21 publications

Infrared thermography technique as an in-situ method of assessing heat loss through thermal bridging

Infrared thermography technique as an in-situ method of assessing heat loss through thermal bridging

Comparison of Various Analysis Methods Based on Heat Flowmeters and Infrared Thermography Measurements for the Evaluation of the In Situ Thermal Transmittance of Opaque Exterior Walls

Temperature-Based Approach for In Situ Evaluation of Thermal Transmittance of Building Walls

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