The prebound-effect in detail: real indoor temperatures in basements and measured versus calculated U-values

Hoffmann, Caroline; Geissler, Achim

doi:10.1016/j.egypro.2017.07.301

Cited by 18 publications

(5 citation statements)

References 2 publications

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“…Moreover, this approach requires the knowledge of the total internal heat transfer coefficient through which the heat flux crossing the wall is calculated. The theory behind this method is the Newton's law of cooling [25], through which the following equation can be written:…”

Section: Background Theory Behind the Methodsmentioning

confidence: 99%

“…Despite the common use of the HFM method, some issues have been highlighted from a metrological and operational point of view. The measurement uncertainty is primarily associated to the heat flow sensor [25]. The heat flow sensor installed on the wall can alter the heat flux, consequently affecting the resulting U-value [36,37].…”

Section: Hfm Methodsmentioning

confidence: 99%

“…An empirical analysis based on the dimensionless groups can be a viable solution for computing the convective heat transfer coefficients, but in this case, a hot-wire anemometer also needs to be used [25,35]. Fluid dynamics phenomena generated by air flows induced by radiators or fan coils may occur and this approach allows each case study to be better investigated, providing specific coefficient values.…”

Section: Thm Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Comparison between Heat Flow Meter (HFM) and Thermometric (THM) Method for Building Wall Thermal Characterization: Latest Advances and Critical Review

et al. 2022

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It is well-known that on-site measurements are suitable for verifying the actual thermal performance of buildings. Performance assessed in situ, under actual thermal conditions, can substantially vary from the theoretical values. Therefore, experimental measurements are essential for better comprehending the thermal behavior of building components, by applying measurement systems and methods suitable to acquire data related to temperatures, heat flows and air speeds both related to the internal and external environments. These data can then be processed to compute performance indicators, such as the well-known thermal transmittance (U-value). This review aims at focusing on two experimental techniques: the widely used and standardized heat flow meter (HFM) method and the quite new thermometric (THM) method. Several scientific papers were analyzed to provide an overview on the latest advances related to these techniques, thus providing a focused critical review. This paper aims to be a valuable resource for academics and practitioners as it covers basic theory, in situ measurement equipment and criteria for sensor installation, errors, and new data post-processing methods.

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Section: Background Theory Behind the Methodsmentioning

confidence: 99%

Section: Hfm Methodsmentioning

confidence: 99%

Section: Thm Methodsmentioning

confidence: 99%

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Comparison between Heat Flow Meter (HFM) and Thermometric (THM) Method for Building Wall Thermal Characterization: Latest Advances and Critical Review

et al. 2022

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“…Considering the widely used standardized HFM method, some issues have been emphasized in the literature [32][33][34]. It has been observed that the measurement uncertainty is principally related to the heat flux sensor [35,36].…”

Section: Aim and Scopementioning

confidence: 99%

Comparison between Direct and Indirect Heat Flux Measurement Techniques: Preliminary Laboratory Tests

Evangelisti,

Barbaro,

Guattari

et al. 2024

Energies

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Direct and indirect approaches can be employed for estimating the heat flow through components in different application fields. In the building sector, the thermometric method is often applied by professionals for thermal transmittance evaluations. However, miscalculations can derive from inaccurate total heat transfer coefficients, and a consensus regarding the appropriate value to employ remains to be determined. Here, an apparatus was realized for laboratory tests and heat flux measurements were performed following direct and indirect approaches. Data acquired through a common heat flow sensor were compared with those computed through a post-processing based on radiative and convective estimations. The results were affected by the specific correlation adopted for computing the convective coefficients, with the percentage differences ranging from −9.8% to −0.4%. New measurement systems could be designed for automatically computing heat fluxes through indirect approaches, thus providing alternative solutions in the panorama of non-destructive tests for building energy diagnosis.

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“…There are discrepancies between standardised values and on-site values, especially because of the contribution of the convective heat exchange, is a well-known problem (e.g. (Emmel et al, 2007;Hoffmann and Geissler, 2017;Palyvos, 2008;Tejedor et al, 2017)).…”

Section: In-situ Vs Nominal Thermal Transmittancementioning

confidence: 99%

Analysis of a non-calorimetric method for assessment of in-situ thermal transmittance and solar factor of glazed systems

Goia

Serra

2018

Solar Energy

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The performance of glazing systems is usually assessed through the thermal transmittance and the solar factor, two metrics characterised either through calorimetric laboratory tests or calculations. In this paper, the analysis of the performance of a non-calorimetric method for obtaining the in-situ thermal transmittance and solar factor of glazing systems is presented. This method, developed as a trade-off between accurate (and expensive) laboratory tests (which characterise the systems under standardised, "averaged" conditions), and easy and less expensive tests on systems installed in real buildings ( under real operative conditions), has been previously adopted for the characterisation of different glazed systems, but never presented and discussed in full detail.The method, suitable for full-scale glazing systems installed in buildings or in test cells, is based on the acquisition of temperature, heat flux, and solar irradiance values. Experimental data is then processed through simple equations and linear regressions to determine the thermal transmittance and the solar factor under real boundary conditions. In this paper, a detailed description of the method, the experimental test rig, and the related expected accuracy is reported. The method is then applied to a case study (a conventional double glazed unit) to give an example of the proposed procedure and to validate it.The results of the case study show the capability of the assessed in-situ thermal transmittance and solar factor to replicate the thermophysical behaviour of the glazing system within a satisfactory degree of accuracy. An in-depth discussion on the observed outcomes from the case study deepens the understanding of the method's performance and the results' significance. *Unmarked Revised Manuscript Click here to view linked References

show abstract

The prebound-effect in detail: real indoor temperatures in basements and measured versus calculated U-values

Cited by 18 publications

References 2 publications

Comparison between Heat Flow Meter (HFM) and Thermometric (THM) Method for Building Wall Thermal Characterization: Latest Advances and Critical Review

Comparison between Heat Flow Meter (HFM) and Thermometric (THM) Method for Building Wall Thermal Characterization: Latest Advances and Critical Review

Comparison between Direct and Indirect Heat Flux Measurement Techniques: Preliminary Laboratory Tests

Analysis of a non-calorimetric method for assessment of in-situ thermal transmittance and solar factor of glazed systems

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