Hygrothermal simulations and In-situ measurements of ultra-lightweight concrete panels

Orosz, Máté; Nagy, Balázs; Tóth, Elek

doi:10.1556/606.2017.12.3.7

Cited by 4 publications

(4 citation statements)

References 16 publications

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“…For the other materials, data were not available from the manufacturer; thus, the conductivity reported in a previous study [31] was used. In previous studies [45][46][47][48], the conductivity of a material changed with temperature and moisture content, affecting the U-value of the wall; however, this was not considered in this study. Many previous studies also utilized the conventional surface resistance values given in ISO 6946 [1] to calculate the theoretical U-value of walls.…”

Section: Test Wallmentioning

confidence: 96%

“…In addition to the aforementioned factors, the discrepancies between theoretical and measured values are also influenced by the nature of the wall, method of analysis, quality of construction, age of the material, and inaccurate thermophysical properties of the material. Recently, several studies have shown that the application of surface resistances that differ from onsite measurements [40][41][42][43][44] and changes in the conductivity of materials due to temperature and moisture [45][46][47][48] can be the main causes of discrepancies.…”

Section: Introductionmentioning

confidence: 99%

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Influences of Average Temperature Difference and Measurement Period on Estimation of In Situ Thermal Transmittance of Building Exterior Walls Using the Average Method of ISO 9869-1

Lee,

Moon,

Choi

et al. 2024

Energies

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Many studies have sought to overcome the two main limitations of the average method of ISO 9869-1—its long test duration and low accuracy. These studies reported that the reliability of the results is dependent on the temperature differences. This consensus was based on the results of studies that measured a few cases with specific temperature differences, and the convergence criteria utilized for the representative thermal transmittance (U-value) were rarely examined. This study analyzed the influence of the average temperature difference and test duration on the convergence characteristics and accuracy of U-value estimation using the average method. Data from a north-facing exterior wall with a theoretical U-value of 0.145 W/m2·K were measured between June 2022 and May 2023. The influences of different measurement conditions were analyzed for cases divided based on four measurement periods and 11 average air temperature differences. The findings show that an accurate U-value can be obtained from 7 days’ worth of measurement data with an average temperature difference of 10 °C or higher and that the improvement in accuracy is minimal under stricter conditions. To achieve a convergence probability of over 90% for temperature differences of 10 °C or greater, the second and third criteria required measurement periods of 7 and 15 days respectively.

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Section: Test Wallmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Influences of Average Temperature Difference and Measurement Period on Estimation of In Situ Thermal Transmittance of Building Exterior Walls Using the Average Method of ISO 9869-1

Lee,

Moon,

Choi

et al. 2024

Energies

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“…For example, out of 340 publications listed on the website of WUFI, there are only 22 English language papers dealing with the 2D analysis of building constructions. The possibility of creating multidimensional simulations by using commercial software started in 2000 when the Fraunhofer Institute presented the WUFI 2D [15] with many applications since then [16], [17]. Besides WUFI, there are other available tools, such as Comsol Multiphysics, which is also capable of performing conjugated heat and moisture transport simulations according to EN 15026 [18].…”

Section: Literature Reviewmentioning

confidence: 99%

Global warming potential of building constructions based on heat and moisture transport analysis

2022

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Global Warming Potential (GWP) is one of the most important Life Cycle Assessment (LCA) indicator, which shows how much heat a greenhouse gas traps in the atmosphere relative to carbon dioxide. In this study, we calculated the GWP of a highly insulated building construction detail of a residential nearly-zero energy building (nZEB) based on numerical simulations. To calculate the heat loss of building constructions, which is necessary for estimating the operational energy demand in the use phase of the building, we compared two numerical simulation methods: 2D thermal simulations and 2D conjugated heat and moisture transfer (HAM) simulations. Besides that, we compared the effect of selecting different thermal insulation materials for insulating the building constructions, such as EPS, mineral wool and wood wool. We then compared the thermal and linear thermal transmittances from the simulations besides evaluating the moisture transmittance behaviour of the constructions. In all examined scenarios, the constructions with mineral wool ended up being the highest impact alternative, while EPS was the lowest for walls and wood wool was for wall corner joints. We also found that including the wall corner joints in GWP calculations could increase the overall GWP of an average-sized family house by 10%. Our study shows the HAM induced differences between thermal insulations, and demonstrates that HAM modelling-based LCA of building construction details gives valuable additional information to designers to choose the proper thermal insulation.

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“…A new addition to the documents related to in-situ measurement of thermal resistance of building partitions is the ISO 9869-2 standard, which introduces the infrared camera method [ 28 ]. In issues related to heat transfer through building partitions and the determination of their thermal resistance, a very important issue is to take into account the variability of material moisture and its transfer [ 29 , 30 ]. However, this research problem was not within the scope of this article.…”

Section: Introductionmentioning

confidence: 99%

Non-Destructive Possibilities of Thermal Performance Evaluation of the External Walls

Nowak

2021

Materials

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Identification of the actual thermal properties of the partitions of building enclosures has a significant meaning in determining the actual energy consumption in buildings and in their thermal comfort parameters. In this context, the total thermal resistance of the exterior walls (and therefore their thermal transmittance) in the building is a major factor which influences its heat losses. There are many methods to determine the total thermal resistance of existing walls, including the quantitative thermography method (also used in this study). This paper presents a comparison of the calculated total thermal resistance values and the measured ones for three kinds of masonry walls without thermal insulation and the same walls insulated with expanded polystyrene boards. The measurements were carried out in quasi-stationary conditions in climate chambers. The following three test methods were used: the temperature-based method (TBM), the heat flow meter method (HFM) and the infrared thermography method (ITM). The measurement results have been found to be in good agreement with the theoretically calculated values: 61% of the measured values were within 10% difference from the mean value of total thermal resistance for a given external wall and 79% of the results were within 20% difference. All of the used measuring methods (TBM, HFM and ITM) have proven to be similarly approximate in obtained total thermal resistances, on average between 6% and 11% difference from the mean values. It has also been noted that, while performing measurements, close attention should be paid to certain aspects, because they can have a major influence on the quality of the result.

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Hygrothermal simulations and In-situ measurements of ultra-lightweight concrete panels

Cited by 4 publications

References 16 publications

Influences of Average Temperature Difference and Measurement Period on Estimation of In Situ Thermal Transmittance of Building Exterior Walls Using the Average Method of ISO 9869-1

Influences of Average Temperature Difference and Measurement Period on Estimation of In Situ Thermal Transmittance of Building Exterior Walls Using the Average Method of ISO 9869-1

Global warming potential of building constructions based on heat and moisture transport analysis

Non-Destructive Possibilities of Thermal Performance Evaluation of the External Walls

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