Experimental validation of a numerical code by thin film heat flux sensors for the resolution of thermal bridges in dynamic conditions

Ascione, Fabrizio; Bianco, Nicola; Masi, Rosa Francesca De; Mauro, Gerardo Maria; Musto, Marilena; Vanoli, Giuseppe Peter

doi:10.1016/j.apenergy.2014.03.014

Cited by 43 publications

(19 citation statements)

References 17 publications

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“…The experiment validated the numerical predictions made using thermal analysis software. Similarly, ITT was used by Ascione et al [29], [30] as a supporting technique to visualize the location of the thermal bridge in order to optimally position a set of heat flow meters and thin flux sensors around it. The heat flux measurements were used as a reference to verify the reliability of a proposed simplified numerical code to effectively and quickly assess the heat loss through thermal bridges.…”

Section: Methods Of Assessing the Thermal Bridge Heat Lossmentioning

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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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: Methods Of Assessing the Thermal Bridge Heat Lossmentioning

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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“…Bianchi et al [106] also proposed an IRT quantitative methodology to assess building envelope thermal losses due to thermal bridges, and Asdrubali et al [78] proposed a methodology to perform a quantitative analysis of some sorts of thermal bridges through simple thermographic surveys and subsequent analytical processing. The IRT was also used by Ascione et al [107] as part of an experimental apparatus to evaluate thermal bridging effects under dynamic conditions. In fact, the evaluation of the multidimensional and dynamic aspects of thermal bridges is very challenging and it should not be neglected when performing dynamic simulations using building energy simulation programs [108].…”

Section: System and Equipment Components And Their Characteristicsmentioning

confidence: 99%

Laboratory and in-situ non-destructive methods to evaluate the thermal transmittance and behavior of walls, windows, and construction elements with innovative materials: A review

Soares

Martins

Gonçalves

et al. 2019

Energy and Buildings

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The experimental characterization of the overall thermal transmittance of homogeneous, moderately-and non-homogeneous walls, windows, and construction elements with innovative materials is very important to predict their thermal performance. It is also important to evaluate if the standard calculation methods to estimate the U-value of new and existing walls can be applied to more complex configurations, since the correct estimation of this value is a critical requirement when performing building energy simulations or energy audit. This paper provides a survey on the main methods to measure the thermal transmittance and thermal behaviour of construction elements, considering laboratory conditions and in-situ non-destructive measurements. Five methods are described: the heat flow meter (HFM); the guarded hot plate (GHP); the hot box (HB), considering the guarded HB (GHB) and the calibrated HB (CHB); and the infrared thermography (IRT). Then, previous studies dedicated to the assessment of the thermal performance of different heavy-and light-weight walls are discussed. Particular attention is devoted to the measurement of the U-value of nonhomogeneous walls, including the effect of thermal bridging caused by steel framing or mortar joints, and the presence of PCMs or new insulation materials in the configuration of the walls. hot box; calibrated hot box; infrared thermography. Highlights: -Review on the main methods to measure the U-value of non-homogeneous walls. -Methods: heat flow meter, guarded hot plate, guarded and calibrated hot box, infrared thermography. -Standards framework and discussion of the main advantages and drawbacks of each method. -Description of methodologies and working principles of laboratory and in-situ measurements. -Measurement of the thermal transmittance of different heavy-and light-weight walls.

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“…Gao [11] and Tadeu [12] used a reduction technique to reduce the complexity of a 3D heat transfer model. Ascione [13,14] used a 2D and 1D numerical model due to the comparing effects of thermal bridges between calculated and measured values. Sierra [15] used a 2D model to assess thermal bridges, because they occur around windows.…”

Section: Introductionmentioning

confidence: 99%

A Simplified Methodology for Evaluating the Impact of Point Thermal Bridges on the High-Energy Performance of a Passive House

et al. 2015

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Abstract:In the design of high-energy performance buildings with ventilated facade systems, the evaluation of point thermal bridges is complicated and is often ignored in practice. This paper analyzes the relationship between the point thermal bridges resulting from aluminum fasteners, which are used for installation facades cladding, and the thermal properties of materials that are used in external walls layers and dimension of layers. Research has shown that the influence of the point thermal bridges on the U-value of the entire wall may achieve an average of up to 30% regarding thermal properties of materials of the external wall layers and the dimension of layers. With the increase in thermal conductivity of the bearing layer material and the thickness of the thermal insulation layer, the point thermal transmittance χ-value increased. For this reason, the U-value of the entire wall may increase by up to 35%. With the increase of the thickness of the bearing layer and thermal conductivity value of thermal insulation layer, the point thermal transmittance χ-value decreased by up to 28%. A simplified methodology is presented for the evaluation of point thermal bridges based on the thermal and geometrical properties of external wall layers.

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Experimental validation of a numerical code by thin film heat flux sensors for the resolution of thermal bridges in dynamic conditions

Cited by 43 publications

References 17 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

Laboratory and in-situ non-destructive methods to evaluate the thermal transmittance and behavior of walls, windows, and construction elements with innovative materials: A review

A Simplified Methodology for Evaluating the Impact of Point Thermal Bridges on the High-Energy Performance of a Passive House

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