Thermal bridges: what software for the calculation? – Ingegneri.info

Through the software and ‘can make the numerical calculation of thermal bridges present in the building envelope. Here is a summary of their characteristics

Usually
 the Software
 that implement the numerical codes have a great
 flexibility for the evaluation of the analysis of the detail is
 of temperatures of heat flows that lead to
 determination of the transmittance
 Thermal bridge
 Heat Ψ .
 Often, however, are difficult to use and require considerable costs
 for the purchase of the license. There are also software
 totally free, but that do not return directly
 desired result; in some cases require additional calculations
 in addition to those of the software in order to obtain the transmittance
 Thermal thermal bridge.

READ MORE ‘ON THERMAL BRIDGES: How to spot a thermal bridge with thermal imaging;

Evaluation and Classification; discontinuities’ thermal; a practical case of thermal bridge to be corrected;

because it ‘s important to the analysis; correction in new buildings

I
 calculation methods to high accuracy, also known numerical methods,
 can be classified into two types: a method to elements
 Gone and the method
  finite difference .
 Both methods provide for a division of the object
 calculation considered in small cells (discretization of the model);
 in principle, the finer the division (the number of cells
 high), the higher the detail resolving or more
 accurate results will be. A high number of subdivisions
 involves, accordingly, a large number of equations to be solved
 as the number of subdivisions is proportional to the number
 equations.

The
 resolution techniques can be either direct
 that type of iterative .
 In general many calculation software implementing the second type of
 resolution, more suitable for the search of the optimal solution. There
 optimal solution identifies the range of temperatures within
 object. The temperatures of the cells or subdivisions
 obtained from the calculation may be used to assess the
 remaining temperatures through interpolation. Consequently may
 be evaluated all the incoming and outgoing heat flows for
 the object of calculation.

Requirements
 software to calculate the thermal bridges

In
 Europe Software
 for the calculation of bridges
 thermal must
 meet the validation requirements set out in Appendix A
 UNI EN ISO 10211. Currently on the market there are various
 software validated to this standard are able to analyze and
 calculate both a two-dimensional and three-dimensional thermal bridge. Yes
 contains a list in table
 not exhaustive of the software validated according to EN ISO 10211,
 specifying the type of 2D or 3D model, and if you can get
 directly to the transmittance of the thermal bridge Ψ .

 numerical calculation method adopted by the software for thermal bridges

Although
 the use of a software
 validated is a necessary condition for evaluating a bridge
 Heat in agreement
 EN ISO 10211, the result can not be
 if they are not properly respected the requirements of the standard.

In
 Generally, the method of calculation should be able to provide the temperatures and
 heat flows at each point of the component to be evaluated. Furthermore, the
 degree of subdivision of the object (ie, the number of cells, or of
 nodes) must be able to be defined by the user (within the limits
 the capacity of the machine).

A
 Another requirement of the law is that, with increasing
 number of subdivisions, the solution of the method to validate
 converges to an analytic solution (if there is a solution). This One
 implies that the creation of the model is not trivial, and the result
 final may not be accurate as required by law.
 The UNI EN ISO 10211 reports that the number of divisions must be
 so determined as to minimize the percentage error between two
 results of heat flows: the first evaluated with a number of
 nodes (for example, “n”) and the second with a given number of
 nodes equal to twice (specifically, equal to “2n”). The difference
 of the two heat flows calculated must not be greater than 1%
 otherwise you must increase the number of subdivisions until
 the criterion is not met.

Some
  Software
 of calculation are implemented so as to allow a subdivision
 automatic, while in others the number of nodes is determined
 user. In other words, it is sufficient to use a software
 numerical calculation to obtain an accurate result, but it is
 must use the settings correctly. For this
 Therefore, in case where the software makes available a report of
 calculation, you need to attach to any of the calculations,
 in addition to the coupling coefficient L _2D
 or L _3D ,
 the number of divisions, the thermal transmittance Ψ
 (Or the punctual X )
 and the difference of the residual error as a function of the number of
 subdivisions chosen.
 

About the Author

Kristian Fabbri

Architect,
 Professor of Environmental Technical Physics and Modeling
 Behavioural Energy
 DA – Department of Architecture, Alma Mater Studiorum University
 Bologna, consultant associations
 Category New Quasco and Emilia-Romagna in the field of
 performance and energy certification of buildings, markets
 Environmental and Energy management. He has authored publications
 magazines and national and international conferences as well as monograph and
 technical manuals.

About the Author

Cosimo Marinosci

Engineer,
 researcher of the Department of Industrial Engineering (DIN), School
 Engineering and Architecture, Alma
 Mater Studiorum University of Bologna, and consultant for NuovaQuasco
 Emilia-Romagna region in the field of performance and certification
 efficiency of buildings, Expert in Energy Management (EGE) and
 on issues relating to energy dynamics simulations
 of buildings. He has authored publications in journals that scientifi
 national and international.

References Editorials

Thermal bridges in buildings

I
 thermal bridges are one of the most complex in the
 assessing the energy performance of buildings. The
 volume is a useful and flexible tool for all professionals
 construction industry (architects, engineers, surveyors, construction experts and
 HVAC), to identify and assess correct discontinuities
 heat due to the presence of thermal bridges in buildings.

The
 Authors analyze the causes and types of thermal bridges, describe
 the impact on the building and on the indoor thermal comfort (aspects
 energy, sanitation, reduction of comfort) and offer
 solutions and examples for managing the calculation of thermal bridges and
 correction of the critical points to improve the energy efficiency
 building.

A
 rich final section of cases and examples clearly explains how
 operate efficient interventions for corrections of thermal bridges.

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