Simulation of dynamic linear thermal bridges using a boundary element method model in the frequency domain

Tadeu, A.; Simões, I.; Simões, N.; Prata, J.

doi:10.1016/j.enbuild.2011.10.001

Cited by 43 publications

(33 citation statements)

References 11 publications

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“…There are numerous scientific studies where linear thermal bridges have been investigated by different calculation and simulation methodologies, such as static/dynamic and 1D/2D/3D. 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.…”

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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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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“…An interesting 3D numerical study on the influence of outdoor environmental conditions on building energy performance has been carried out by He et al [21] by using a proprietary algorithm, but neglecting the presence of thermal bridges in the building envelope. Recently, Tadeu et al [1] proposed a 2D dynamic model, based on the boundary element method in the frequency domain, to characterize wall corners and estimate their influence on the thermal performance of building components. Theodosiou et al [22] carried out 3D heat transfer simulations of cladding systems for building facades, showing that neglecting the point thermal bridge effect in these kind of systems can lead to a significant underestimation (from 5% to 20%) of actual heat flows.…”

Section: Review Of the Available Literaturementioning

confidence: 99%

“…Nowadays, a great deal of attention has been given to efficient energy use in the heating and cooling sector, and building envelopes play a crucial role in the reduction of the energy consumption and the related costs. In fact, building heating and cooling are responsible for about 40% of the final energy consumption in the European Union (EU) and, as a consequence, for a considerable amount of total CO 2 emissions [1]. The attention to the issue of energy efficiency in buildings is demonstrated by international and national directives [2-5], which describe the procedure for energy certification of buildings, and require member states to ensure that new and existing buildings meet minimum energy performance requirements, monitoring the actual energy demand or the estimated energy necessary to meet the various needs related to standard building uses, such as heating and cooling.…”

Section: Introductionmentioning

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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“…So far, some attempts to use BEM for modeling thermal bridges have been made by Tadeu et al In [20], the mathematical algorithm has been developed for analysis of linear thermal bridges. A computational algorithm was formulated in the frequency domain for transient and steady heat conduction, where external and internal temperatures are time-dependent.…”

Section: Introductionmentioning

confidence: 99%

BEM Utility for Simulation of Linear Thermal Bridges

Werner-Juszczuk

Rynkowski

2016

CMST

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This paper aims to prove utility of the boundary element method for modelling 2D heat transfer in complex multiregions, particularly in thermal bridges. It proposes BEM as an alternative method commonly applied in commercial software for simulation of temperature field and heat flux in thermal bridges, mesh methods (FEM, FDM).The BEM algorithm with Robin boundary condition is developed for modelling 2D heat transfer in complex multi-regions. Simulation is performed with the authoring Fortran program. The developed mathematical algorithm and computer program are validated according to standard EN ISO 10211:2007. Two examples of complex thermal bridges that commonly appears in house building are presented. Analysis of two reference cases, listed in standard ISO, confirms utility of the proposed BEM algorithm and Fortran program for simulation of linear thermal bridges. Conditions, quoted in standard ISO, are satisfied with models of a relatively small number of boundary elements. Performed validation constitutes the base for further development of BEM as an efficient method for modelling heat transfer in building components, and for the prospective application in commercial software.

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Simulation of dynamic linear thermal bridges using a boundary element method model in the frequency domain

Cited by 43 publications

References 11 publications

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

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

BEM Utility for Simulation of Linear Thermal Bridges

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