Problems in the calculation of thermal bridges in dynamic conditions

Martín-Escudero, Koldobika; Erkoreka, Aitor; Flores, I.; Odriozola, Miguel Ángel Bermúdez; Sala, J.M.

doi:10.1016/j.enbuild.2010.10.018

Cited by 94 publications

(52 citation statements)

References 4 publications

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“…The model is based on a nodal description of the building elements with a one dimensional modelling of the thermal phenomena occurring in the building (i.e., transverse heat transfer often plays a minor role in the building conduction phenomena [37]). In addition, in order to analyze the effect of the spatial distribution of the heat capacity on the heat flux through the building envelope elements, the thermal network approach, based on a high number of thermal capacitances is taken into account (i.e., distributed parameters model [38]).…”

Section: Framework and General Model Descriptionmentioning

confidence: 99%

Code-to-Code Validation and Application of a Dynamic Simulation Tool for the Building Energy Performance Analysis

Buonomano

2016

Energies

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Abstract:In this paper details about the results of a code-to-code validation procedure of an in-house developed building simulation model, called DETECt, are reported. The tool was developed for research purposes in order to carry out dynamic building energy performance and parametric analyses by taking into account new building envelope integrated technologies, novel construction materials and innovative energy saving strategies. The reliability and accuracy of DETECt was appropriately tested by means of the standard BESTEST validation procedure. In the paper, details of this validation process are accurately described. A good agreement between the obtained results and all the reference data of the BESTEST qualification cases is achieved. In particular, the obtained results vs. standard BESTEST output are always within the provided ranges of confidence. In addition, several test cases output obtained by DETECt (e.g., dynamic profiles of indoor air and building surfaces temperature and heat fluxes and spatial trends of temperature across walls) are provided.

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Section: Framework and General Model Descriptionmentioning

confidence: 99%

Code-to-Code Validation and Application of a Dynamic Simulation Tool for the Building Energy Performance Analysis

Buonomano

2016

Energies

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“…It is especially important in the design of buildings with ventilated facade systems, where profiles of thermal insulation panels are fixed directly to the bearing layer of walls or brackets are used in order to reduce the influence of a thermal bridge on the properties of the thermal insulation layer [22]. Studies show that if solid metal profiles (which penetrate the thermal insulation layer) are used to fix thermal insulation, the thermal resistance might be cut in half [23][24][25]. If these additional heat losses incurred due to point thermal transmittance are neglected or evaluated incorrectly, the energy efficiency calculations for the building may be incorrect.…”

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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“…However, in order to take into account actual transient conditions, a number of works have studied thermal behavior of linear thermal bridges, to analyze their contribution to the total energy performance of buildings. The phenomenon depends on several factors, such as external and internal conditions, level of insulation, geometry of the thermal bridge and materials used, structure and use of building, and the results of calculations, unlike reality, often depend on the model used to calculate its effects on building energy demand [14]. Therefore, estimates of the actual weight of thermal bridges on the energy demand of buildings can vary from 5%, in the case of retrofitting the exterior of the building envelope, to 39% in well insulated single family houses without proper thermal bridge treatment [14].…”

Section: Review Of the Available Literaturementioning

confidence: 99%

Effects of Inhomogeneities on Heat and Mass Transport Phenomena in Thermal Bridges

2016

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Abstract:The interest of calculating the effects of thermal bridges in buildings energy consumption is growing, due to recent energy saving regulations applied in different countries. The widespread use of insulating materials to reduce energy requirements of buildings, often employed for intermediate insulation of the building envelope, makes thermal bridges a crucial point in the energy analysis of building envelopes. Furthermore, heat losses through thermal bridges often lead to building pathologies due to moisture condensation. Therefore, thermal bridges need to be correctly characterized in the building design stage in order to reduce heat losses and avoid materials degradation. The authors numerically simulate, by using finite elements, the steady-state and dynamic three-dimensional (3D) heat and vapor transport in inhomogeneous thermal bridges and building envelopes. The aim of the present work is to show the importance of taking into account the presence of inhomogeneities (i.e., metal stud) in building materials for the calculation of actual heat losses and water condensation in 3D thermal bridges. The obtained heat transfer results are verified against the reference data of the technical standard UNI EN ISO 10211. The proposed microscopic approach is essential to calculate the actual heat losses of three-dimensional thermal bridges and building envelopes and to overcome condensation problems.

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Problems in the calculation of thermal bridges in dynamic conditions

Cited by 94 publications

References 4 publications

Code-to-Code Validation and Application of a Dynamic Simulation Tool for the Building Energy Performance Analysis

Code-to-Code Validation and Application of a Dynamic Simulation Tool for the Building Energy Performance Analysis

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

Effects of Inhomogeneities on Heat and Mass Transport Phenomena in Thermal Bridges

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