Modeling of transient conduction in building envelope assemblies: A review

Pilet, Tyler; Rakha, Tarek

doi:10.1080/23744731.2022.2068315

Cited by 3 publications

(2 citation statements)

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“…The matrices (14) are the input values for the algorithm [24] to calculate the CTF coefficients Z j , Y j and ϕ j . The algorithm [24] is implemented in Mathematica [25], and all operations with matrices were performed using this powerful software.…”

Section: The State-space Methodsmentioning

confidence: 99%

“…Due to the long analysis period and small time steps used for the analysis, numerical methods have proven to be inadequate for building energy simulations because they rely on solving large systems of equations at each time step [13]. Analytical methods such as conduction transfer functions (CTFs) have been shown to be much better for building energy simulation problems [14] and are implemented in modern dynamic energy simulation software such as TRNSYS [15] and EnergyPlus [16]. Although the CTF methods are superior to the abovementioned simplified calculations, the aim of this research is to show that they have their limitations and lead to unsatisfactory results if not properly applied.…”

Section: Introductionmentioning

confidence: 99%

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Laplace and State-Space Methods for Calculating the Heat Losses in Case of Heavyweight Building Elements and Short Sampling Times

et al. 2023

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Reducing heat losses through the building envelope is one of the most important aspects to be met if the targets set by the European Union are to be achieved. In order to obtain a more realistic energy demand, dynamic heat transfer simulations are used to calculate the energy consumption of buildings, since steady-state calculations do not take into account the thermal mass in buildings. These dynamic simulations employ methods based on analytical models since numerical models are unsuitable for longer time periods. The analytical models used herein fall into the category of conduction transfer functions (CTFs). Two methods for computing CTFs that are addressed in this research are the Laplace method and the State-Space method. The objective of this paper is to verify the efficiency of the Laplace and State-Space methods for calculating the energy demand of a building in the case of heavyweight building elements and shorter sampling times, and to provide a means for improving the algorithms used by these methods. The Laplace and State-Space method algorithms were implemented in Mathematica, and the results were compared to EnergyPlus and TRNSYS, which use similar algorithms to calculate energy demand. It was shown in this paper that for the heavyweight wall element and a time step of 0.25 h, the difference between the total energy transferred through the inner surface was about 31% for EnergyPlus and 78% for TRNSYS compared to the reference solution. For the lightweight wall element, the results were stable for the time step of 0.25 h, but for the time step of 0.1 h, the differences were 45.64% and 303% between EnergyPlus, TRNSYS and the reference solution, respectively, compared to the State-Space and Laplace methods for which the maximum difference was 12.03% with a time step of 0.1 h. While dynamic heat transfer simulations are better than calculations based on steady-state boundary conditions, they also have their limitations and could lead to unsatisfactory results for short sampling times and if not applied properly.

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Section: The State-space Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%