scholarly journals Calculation of Building Heat Losses through Slab-on-Ground Structures Based on Soil Temperature Measured In Situ

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 114
Author(s):  
Iwona Pokorska-Silva ◽  
Marta Kadela ◽  
Bożena Orlik-Kożdoń ◽  
Lidia Fedorowicz
Keyword(s):  
Heat Flux ◽  
Heat Flow ◽  
Soil Temperature ◽  
Geometric Model ◽  
Residential Building ◽  
Numerical Analyses ◽  
Ground Structure ◽  
The Difference ◽  
Wall Foundation

The article aims to assess the effects of soil temperature measured in situ on the heat loss analyses of a building. Numerical analyses and in situ measurements of soil temperature profiles for real conditions under a residential building (profile I) in Poland and under the area outside the building (profile II) were performed. Based on the measurement results, a proprietary geometric model of the partition was proposed. The heat flux and heat flow results obtained for reliable models are 4.9% and 6.9% higher compared to a model based on a typical meteorological year for the wall–foundation system and 10.0% and 10.1% higher for the slab-on-ground structure for profile I. The adoption of temperatures from the area outside the building as the boundary condition (profile II) results in greater differences between the obtained results. The difference in heat flow obtained in the numerical analyses for profiles I and II is about 2 W/m2, both for the wall–foundation system and for the slab-on-ground structure calculations. The adoption of temperatures for the ground outside the building led to overestimation in the heat flux calculations, this being due to lower temperatures in these particular layers of the ground.

scholarly journals Thermal Performance Optimization and Experimental Evaluation of Vacuum-Glazed Windows Manufactured via the In-Vacuum Method

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3634
Author(s):  
Jaesung Park ◽  
Myunghwan Oh ◽  
Chul-sung Lee
Keyword(s):  
Energy Efficiency ◽  
Heat Flow ◽  
Thermal Performance ◽  
Performance Optimization ◽  
Residential Building ◽  
Vacuum Method ◽  
The Difference ◽  
Insulation Performance ◽  
Manufacturing Time ◽  
Indoor And Outdoor

Windows are essential in buildings; however, they have poor thermal performance, so extensive research has been conducted on improving their performance. In this study, we developed vacuum-glazed windows with excellent insulation via the in-vacuum method, which shortens the manufacturing time and vacuuming degree considerably. In addition, the configuration of the pillars, low-emissivity (low-e) coating, and frame from a thermal performance perspective was experimentally optimized. The results revealed that the optimal pillar placement spacing is 40 mm and that the low-e coating surface must be located inside the vacuum layer to maximize insulation performance. The vacuum-glazed window produced by the in-vacuum method was applied to an actual residential building to investigate its thermal performance, which was compared with that of a triple-glazed window. The results showed that the center-of-glazing heat flow of the vacuum-glazed window was approximately 0.8 W/m2K lower than that of the triple-glazed window. The difference between the average indoor and outdoor surface temperatures during the nighttime was found to be up to 35.1 °C for the vacuum-glazed window and 23.1 °C for the triple-glazed window. Therefore, the energy efficiency of the building can be greatly improved by applying vacuum windows manufactured via the in-vacuum method and optimized for the best thermal performance.

scholarly journals Heat-flow variability of suspended timber ground floors: Implications for in-situ heat-flux measuring

2017 ◽  
Vol 138 ◽  
pp. 396-405 ◽  
Author(s):  
S. Pelsmakers ◽  
R. Fitton ◽  
P. Biddulph ◽  
W. Swan ◽  
B. Croxford ◽  
...  
Keyword(s):  
Heat Flux ◽  
Heat Flow ◽  
Flow Variability

scholarly journals Quicker Measurement of Walls’ Thermal Resistance Following an Extension to ISO 9869 Average Method

2019 ◽  
Vol 111 ◽  
pp. 04019
Author(s):  
Arash Rasooli ◽  
Laure Itard
Keyword(s):  
Heat Flux ◽  
Thermal Resistance ◽  
Average Method ◽  
Large Scale ◽  
Accurate Determination ◽  
Acceptable Result ◽  
Heat Flux Meter ◽  
The Difference

Determination of the thermo-physical characteristics of the buildings’ components is crucial to illustrate their thermal behavior and therefore their energy consumption. Along the same line, accurate determination of the thermal resistance of the building walls falls into one the most important targets. Following the difference between in-lab, and on site thermal performance of walls, in-situ measurements have been highly recommended. The most well-known practice for in-situ measurement of walls’ thermal resistance is the Average Method of ISO 9869, using one heat flux meter and two thermocouples. The method, in comparison with other existing methods is quite straight-forward and therefore, is applied widely in large scale. Despite its simplicity, this method usually needs a relatively long time to reach an acceptable result. The current paper deals with a modification to the ISO 9869 method, making it in many situations much quicker than its original state. Through simulation of walls of different typologies, it is shown in which cases the measurement period becomes longer than expected. It is demonstrated how the addition of a heat flux meter to the aforementioned equipment can lead to a much quicker achievement of the thermal resistance, following the rest of the instructions of the standard method.

scholarly journals Variability of Air–Sea Interactions over the Indian Ocean Derived from Satellite Observations

1998 ◽  
Vol 11 (8) ◽  
pp. 1859-1873 ◽  
Author(s):  
Catherine Gautier ◽  
Peter Peterson ◽  
Charles Jones
Keyword(s):  
Heat Flux ◽  
Indian Ocean ◽  
Interannual Variability ◽  
Satellite Data ◽  
Large Scale ◽  
Southwest Monsoon ◽  
Seasonal And Interannual Variability ◽  
The Indian Ocean ◽  
The Difference

Abstract Novel ways of monitoring the large-scale variability of the southwest monsoon in the Indian Ocean are presented using multispectral satellite datasets. The fields of sea surface temperature (SST), surface latent heat flux (LHF), net surface solar radiation (SW), precipitation (P), and SW − LHF over the Indian Ocean are analyzed to characterize the seasonal and interannual variability with special emphasis on the period 1988–90. It is shown that satellite data are able to make a significant contribution to the multiplatform strategy necessary to describe the large-scale spatial and temporal variability of air–sea interactions associated with the Indian Ocean Monsoon. The satellite data analyzed here has shown for the first time characteristics of the interannual variability of air–sea interactions over the entire Indian Ocean. Using monthly means of SST, LHF, SW, P, and the difference SW − LHF, the main features of the seasonal and interannual variability of air–sea interactions over the Indian Ocean are characterized. It is shown that the southwest monsoon strongly affects these interactions, inducing dramatic exchanges of heat between air and sea and large temporal variations of these exchanges over relatively small timescale (with regards to typical oceanic timescales). The analyses indicate an overall good agreement between satellite and in situ (ship) estimates, except in the southern Indian Ocean, where ship sampling is minimal, the disagreement can be large. In the latitudinal band of 10°N–15°S, differences in climatological in situ estimates of surface sensible heat flux and net longwave radiation has a larger influence on the net surface heat flux than the difference between satellite and in situ estimates of SW and LHF.

scholarly journals Análise Comparativa do Fluxo de Calor no Solo em Profundidade e na Superfície (Brazil Comparative Analysis of Soil Heat Flux in Depth and Surface)

2013 ◽  
Vol 6 (4) ◽  
pp. 665
Author(s):  
Willames Albuquerque Soares
Keyword(s):  
Heat Flux ◽  
Comparative Analysis ◽  
Thermal Diffusivity ◽  
Heat Flow ◽  
Soil Temperature ◽  
Soil Surface ◽  
Soil Heat Flux ◽  
Clear Sky ◽  
Harmonic Method ◽  
Sky Conditions

O objetivo deste estudo é comparar os resultados do fluxo de calor no solo, na superfície e em profundidade, encontrados por sensores de fluxo de calor no solo e pelo método harmônico, em cultivo de mamoneira. No dia sem chuvas, a pouca quantidade de água no solo diminuiu a sua difusividade térmica, provocando um maior acúmulo de energia no solo, e, consequentemente, a elevação na temperatura nas camadas mais próximas à superfície. As principais diferenças entre os valores medidos e estimados aconteceram nos horários de maior insolação, principalmente nos dias em que o céu estava encoberto por nuvens. A presença da vegetação cobrindo o solo influenciou diretamente nos valores medidos e modelados. As estimativas tanto em profundidade como para a superfície do solo se mostraram bastante satisfatórias, tanto em dias de céu claro como para dias de céu encoberto.     A B S T R A C T The aim of this study was to compare the results of soil heat flow, in the surface and depth, found by sensors soil heat flux and by harmonic method, in castor  crop . On days without rainfall, the small amounts of water in the soil decreased its thermal diffusivity, causing a higher energy accumulation in the soil and consequently an increase at a temperature on the layers nearest the surface. The main differences between the measured and estimated values occurred at times of intense sunlight, especially on days when the sky was obscured by clouds. The presence of vegetation covering the soil directly influenced the values measured and modeled. Estimates both in depth and to the soil surface proved very satisfactory, both in clear sky conditions as for overcast days.   Key-Words: Harmonic Method, Soil temperature, soil heat flux plates.

scholarly journals Effects of microtopography on texture, temperature and heat flow in Arctic and sub-Arctic snow

1994 ◽  
Vol 19 ◽  
pp. 63-68 ◽  
Author(s):  
Matthew Sturm ◽  
Jonathan Holmgren
Keyword(s):  
Heat Flux ◽  
Heat Flow ◽  
Snow Depth ◽  
In Situ Measurements ◽  
Temperature Gradients ◽  
Substantial Fraction ◽  
Model Based ◽  
Vertical Heat ◽  
Lateral Temperature

Arctic and sub-Arctic snow is deposited on ground that can have significant microrelief due to tundra hummocks and tussocks. The microrelief, a substantial fraction of the total snow depth, causes basal layers of snow (usually depth hoar) to be discontinuous. In-situ measurements made at four locations in Alaska indicate lateral temperature gradients up to 60°C m−1exist at the snow/ground interface due to the microtopography. For all sites, the winter average range of temperature along a 1.5 m transect at the interface varied from 4°C to greater than 7°C. Heat-flux transducers placed at the tops and bases of tussocks indicated that vertical heat flow was consistently 1.4 to 2.1 times higher at the top than the base. Results of a conductive model based on tussock height are consistent with these measurements.

scholarly journals Microclimatic comparison of lichen heaths and shrubs: shrubification generates atmospheric heating but subsurface cooling during the growing season

2021 ◽  
Vol 18 (5) ◽  
pp. 1577-1599
Author(s):  
Peter Aartsma ◽  
Johan Asplund ◽  
Arvid Odland ◽  
Stefanie Reinhardt ◽  
Hans Renssen
Keyword(s):  
Heat Flux ◽  
Soil Temperature ◽  
Longwave Radiation ◽  
Growing Season ◽  
Soil Heat Flux ◽  
Net Radiation ◽  
Mountain Area ◽  
Atmospheric Heating ◽  
Air Temperatures ◽  
The Difference

Abstract. Lichen heaths are declining in abundance in alpine and Arctic areas partly due to an increasing competition with shrubs. This shift in vegetation types might have important consequences for the microclimate and climate on a larger scale. The aim of our study is to measure the difference in microclimatic conditions between lichen heaths and shrub vegetation during the growing season. With a paired plot design, we measured the net radiation, soil heat flux, soil temperature and soil moisture on an alpine mountain area in southern Norway during the summer of 2018 and 2019. We determined that the daily net radiation of lichens was on average 3.15 MJ (26 %) lower than for shrubs during the growing season. This was mainly due to a higher albedo of the lichen heaths but also due to a larger longwave radiation loss. Subsequently, we estimate that a shift from a lichen heath to shrub vegetation leads to an average increase in atmospheric heating of 3.35 MJ d−1 during the growing season. Surprisingly, the soil heat flux and soil temperature were higher below lichens than below shrubs during days with high air temperatures. This implies that the relatively high albedo of lichens does not lead to a cooler soil compared to shrubs during the growing season. We predict that the thicker litter layer, the presence of soil shading and a higher evapotranspiration rate at shrub vegetation are far more important factors in explaining the variation in soil temperature between lichens and shrubs. Our study shows that a shift from lichen heaths to shrub vegetation in alpine and Arctic areas will lead to atmospheric heating, but it has a cooling effect on the subsurface during the growing season, especially when air temperatures are relatively high.

scholarly journals The decline of alpine lichen heaths generates atmospheric heating but subsurface cooling during the growing season

2020 ◽  
Author(s):  
Peter Aartsma ◽  
Johan Asplund ◽  
Arvid Odland ◽  
Stefanie Reinhardt ◽  
Hans Renssen
Keyword(s):  
Heat Flux ◽  
Soil Temperature ◽  
Longwave Radiation ◽  
Growing Season ◽  
Soil Heat Flux ◽  
Net Radiation ◽  
Mountain Area ◽  
Atmospheric Heating ◽  
Air Temperatures ◽  
The Difference

Abstract. Lichen heaths are declining in abundance in alpine and arctic areas partly due to an increasing competition with shrubs. This shift in vegetation types might have important consequences for the microclimate and climate on a larger scale. The aim of our study is to measure the difference in microclimatic conditions between lichen heaths and shrub vegetation during the growing season. With a paired plot design, we measured the net radiation, soil heat flux, soil temperature, and soil moisture on an alpine mountain area in south Norway during the summer of 2018 and 2019. We determined that the daily net radiation of lichens was on average 3.15 MJ (26 %) lower than for shrubs during the growing season. This was mainly due to a higher albedo of the lichen heaths, but also due to a larger longwave radiation loss. Subsequently, we estimate that a shift from a lichen heath to shrub vegetation leads to an average increase in atmospheric heating of 3.35 MJ per day during the growing season. Surprisingly, the soil heat flux and soil temperature were higher below lichens than below shrubs during days with high air temperatures. This implies that the relatively high albedo of lichens does not lead to a cooler soil compared to shrubs during the growing season. We hypothesize that the thicker litter layer, the presence of soil shading, and a higher evapotranspiration rate at shrub vegetation are far more important factors in explaining the variation in soil temperature between lichens and shrubs. Our study shows that a shift from lichen heaths to shrub vegetation in alpine and arctic areas will lead to atmospheric heating, but has a cooling effect on the subsurface during the growing season, especially when air temperatures are relatively high.

scholarly journals Effects of microtopography on texture, temperature and heat flow in Arctic and sub-Arctic snow

1994 ◽  
Vol 19 ◽  
pp. 63-68 ◽  
Author(s):  
Matthew Sturm ◽  
Jonathan Holmgren
Keyword(s):  
Heat Flux ◽  
Heat Flow ◽  
Snow Depth ◽  
In Situ Measurements ◽  
Temperature Gradients ◽  
Substantial Fraction ◽  
Model Based ◽  
Vertical Heat ◽  
Lateral Temperature

Arctic and sub-Arctic snow is deposited on ground that can have significant microrelief due to tundra hummocks and tussocks. The microrelief, a substantial fraction of the total snow depth, causes basal layers of snow (usually depth hoar) to be discontinuous. In-situ measurements made at four locations in Alaska indicate lateral temperature gradients up to 60°C m −1 exist at the snow/ground interface due to the microtopography. For all sites, the winter average range of temperature along a 1.5 m transect at the interface varied from 4°C to greater than 7°C. Heat-flux transducers placed at the tops and bases of tussocks indicated that vertical heat flow was consistently 1.4 to 2.1 times higher at the top than the base. Results of a conductive model based on tussock height are consistent with these measurements.

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