scholarly journals Calculating human thermal comfort and thermal stress in the PALM model system 6.0

2020 ◽  
Vol 13 (7) ◽  
pp. 3055-3065 ◽  
Author(s):  
Dominik Fröhlich ◽  
Andreas Matzarakis
Keyword(s):  
Thermal Comfort ◽  
City Planning ◽  
Urban Climate ◽  
Climate Index ◽  
Mean Radiant Temperature ◽  
Thermal Indices ◽  
Large Eddy Simulation Model ◽  
Human Thermal Comfort ◽  
Model Based ◽  
Radiant Temperature

Abstract. In the frame of the project “MOSAIK – Model-based city planning and application in climate change”, a German-wide research project within the call “Urban Climate Under Change” ([UC]2) funded by the German Federal Ministry of Education and Research (BMBF), a biometeorology module was implemented into the Parallelized Large-Eddy Simulation Model (PALM) system. The new biometeorology module is comprised of methods for the calculation of UV-exposure quantities, a human–biometeorologically weighted mean radiant temperature (Tmrt), as well as for the estimation of human thermal comfort or stress. The latter is achieved through the implementation of the three widely used thermal indices: perceived temperature (PT), Universal Thermal Climate Index (UTCI), as well as physiologically equivalent temperature (PET). Comparison calculations were performed for the PT, UTCI and PET indices based on the SkyHelios model and showing PALM calculates higher values in general. This is mostly due to a higher radiational gain leading to higher values of mean radiant temperature. For a more direct comparison, the PT, PET and UTCI indices were calculated by the biometeorology module, as well as the programs provided by the attachment to Verein Deutscher Ingenieure (VDI) guideline 3787, as well as by the RayMan model based on the very same input dataset. Results show deviations below the relevant precision of 0.1 K for PET and UTCI and some deviations of up to 2.683 K for PT caused by repeated unfavorable rounding in very rare cases (0.027 %).

scholarly journals Calculating human thermal comfort and thermal stress in the PALM model system 6.0

2019 ◽  
Author(s):  
Dominik Fröhlich ◽  
Andreas Matzarakis
Keyword(s):  
Thermal Comfort ◽  
City Planning ◽  
Model System ◽  
Climate Index ◽  
Mean Radiant Temperature ◽  
Clothing Insulation ◽  
Human Thermal Comfort ◽  
Model Based ◽  
Perceived Temperature ◽  
Radiant Temperature

Abstract. In the frame of the project MOSAIK – Model–based city planning and application in climate change, a German-wide research project within the call Urban Climate Under Change ([UC]2) funded by the German Federal Ministry of Education and Research (BMBF), a biometeorology module was implemented into the PALM model system. The new biometeorology module comprises of methods for the calculation of uv-exposure quantities, a human–biometeorologically weighted mean radiant temperature (Tmrt), as well as for the estimation of human thermal comfort or stress. The latter is achieved through the implementation of the three widely–used thermal indices Perceived Temperature (PT), Universal Thermal Climate Index (UTCI), as well as Physiologically Equivalent Temperature (PET) together with a newly developed instationary index instationary Perceived Temperature (iPT) based on PT for use with the multi–agent model. Comparison calculations were performed for the indices PT, UTCI and PET based on the SkyHelios model and showing PALM calculates higher values in general. This is mostly due to a higher radiational gain leading to higher values of mean radiant temperature. For a more direct comparison, the indices PT, PET and UTCI were calculated by the biometeorology module, as well as the programs provided by the attachment to the VDI guideline 3787, as well as by the RayMan model based on the very same input dataset. Results show deviations below rounding precision (less than 0.1 K) for PET and UTCI and some deviations of up to 2.683 K for PT caused by rounding leading to the selection of a different clothing insulation step in very rare cases (0.027 %).

Design Range of Indoor Relative Humidity in Radiant Cooling Environment

2011 ◽  
Vol 243-249 ◽  
pp. 4905-4908
Author(s):  
Xue Min Sui ◽  
Xu Zhang ◽  
Guang Hui Han
Keyword(s):  
Relative Humidity ◽  
Thermal Comfort ◽  
Mean Radiant Temperature ◽  
Design Standards ◽  
Human Thermal Comfort ◽  
Radiant Cooling ◽  
Climate Parameter ◽  
Radiant Temperature ◽  
Thermal Comfort Model ◽  
The Impact

Relative humidity is an important micro-climate parameter in radiant cooling environment. Based on the human thermal comfort model, this paper studied the effect on PMV index of relative humidity, and studied the relationship of low mean radiant temperature and relative humidity, drew the appropriate design range of indoor relative humidity for radiant cooling systems.The results show that high relative humidity can compensate for the impact on thermal comfort of low mean radiant temperature, on the premise of achieving the same thermal comfort requirements. However, because of the limited compensation range of relative humidity, together with the constraints for it due to anti-condensation of radiant terminal devices, the design range of relative humidity should not be improved, and it can still use the traditional air-conditioning design standards.

scholarly journals Field Assessment of Neighboring Building and Tree Shading Effects on the 3D Radiant Environment and Human Thermal Comfort in Summer within Urban Settlements in Northeast China

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Jing Du ◽  
Lin Liu ◽  
Xin Chen ◽  
Jing Liu
Keyword(s):  
Thermal Comfort ◽  
Air Temperature ◽  
Short Wave ◽  
Radiant Flux ◽  
View Factor ◽  
Mean Radiant Temperature ◽  
Human Thermal Comfort ◽  
Long Wave ◽  
Shading Effects ◽  
Radiant Temperature

Shading is one of the most effective strategies to mitigate urban local-scale heat stress during summer. Therefore, this study investigates the effects of shading caused by buildings and trees via exhaustive field measurement research on urban outdoor 3D radiant environment and human thermal comfort. We analyzed the characteristics of micrometeorology and human thermal comfort at shaded areas, and compared the difference between building and tree shading effects as well as that between shaded and sunlit sites. The results demonstrate that mean radiant temperature Tmrt (mean reduction values of 28.1°C for tree shading and 28.8°C for building shading) decreased considerably more than air temperature Ta (mean reduction values of 1.9°C for tree shading and 1.2°C for building shading) owing to shading; furthermore, the reduction effect of shading on UTCI synthesized the variation in the above two parameters. Within the shaded areas, short-wave radiant components (mean standardized values of 0.104 for tree shading and 0.087 for building shading) decreased considerably more than long-wave radiant components (mean standardized values of 0.848 for tree shading and 0.851 for building shading) owing to shading; the proportion of long-wave radiant flux densities absorbed by the reference standing person was high, leading to a relatively high long-wave mean radiant temperature, and R2 between long-wave mean radiant temperature and air temperature exceeded 0.8. Moreover, the directional sky view factor (SVF) was utilized in this study, and it showed significant positive correlation with short-wave radiant flux densities, but no statistically evident correlation with long-wave radiant flux densities. Meanwhile, Tmrt was most relevant with SVFS⟶ with R2 of 0.9756. Furthermore, UTCI rose two categories at the sunlit areas compared with that at the shaded areas. In contrast, Ta and Tmrt played the first positive role in UTCI at shaded and sunlit areas, respectively.

scholarly journals Investigating the Behaviour of Human Thermal Indices under Divergent Atmospheric Conditions: A Sensitivity Analysis Approach

Atmosphere ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 580 ◽  
Author(s):  
Ioannis Charalampopoulos ◽  
Andre Santos Nouri
Keyword(s):  
Energy Balance ◽  
Thermal Comfort ◽  
Thermal Conditions ◽  
Radiation Condition ◽  
Additive Models ◽  
Balance Model ◽  
Climate Index ◽  
Atmospheric Conditions ◽  
Thermal Indices ◽  
Human Thermal Comfort

This paper aims to analyse and conclude about the behaviour of the most commonly used human thermal comfort indices under a variety of atmospheric conditions in order to provide further information about their appropriateness. Utilising Generalized Additive Models (GAMs), this article examines the indices’ sensitivity when exposed to diverse classified atmospheric conditions. Concentrated upon analysing commonly used human thermal indices, two Statistical/Algebraic indices (Thermohygrometric Index (THI) and HUMIDEX (HUM)), and four Energy Balance Model indices (Physiologically Equivalent Temperature (PET), modified PET (mPET), Universal Thermal Climate Index (UTCI), and Perceived Temperature (PT)) were selected. The results of the study are twofold, the identification of (1) index sensitivity to parameters’ variation, and change rates, resultant of different atmospheric conditions; and, (2) the overall pertinence of each of the indices for local thermal comfort evaluation. The results indicate that the thermohygrometric indices cannot follow and present the thermal conditions’ variations. On the other hand, UTCI is very sensitive under low radiation condition, and PET/mPET present higher sensitivity when the weather is dominated by high radiation and air temperature. PT index provides the lower sensitive among the human energy balance indices, but this is adequately sensitive to describe the thermal comfort environment.

scholarly journals Modeling Mean Radiant Temperature Distribution in Urban Landscapes Using DART

2021 ◽  
Vol 13 (8) ◽  
pp. 1443
Author(s):  
Maria Angela Dissegna ◽  
Tiangang Yin ◽  
Hao Wu ◽  
Nicolas Lauret ◽  
Shanshan Wei ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Thermal Comfort ◽  
Leaf Area ◽  
Remote Sensing Data ◽  
Outdoor Thermal Comfort ◽  
Transfer Model ◽  
Mean Radiant Temperature ◽  
Area Index ◽  
Sensing Data ◽  
Radiant Temperature

The microclimatic conditions of the urban environment influence significantly the thermal comfort of human beings. One of the main human biometeorology parameters of thermal comfort is the Mean Radiant Temperature (Tmrt), which quantifies effective radiative flux reaching a human body. Simulation tools have proven useful to analyze the radiative behavior of an urban space and its impact on the inhabitants. We present a new method to produce detailed modeling of Tmrt spatial distribution using the 3-D Discrete Anisotropic Radiation Transfer model (DART). Our approach is capable to simulate Tmrt at different scales and under a range of parameters including the urban pattern, surface material of ground, walls, roofs, and properties of the vegetation (coverage, shape, spectral signature, Leaf Area Index and Leaf Area Density). The main advantages of our method are found in (1) the fine treatment of radiation in both short-wave and long-wave domains, (2) detailed specification of optical properties of urban surface materials and of vegetation, (3) precise representation of the vegetation component, and (4) capability to assimilate 3-D inputs derived from multisource remote sensing data. We illustrate and provide a first evaluation of the method in Singapore, a tropical city experiencing strong Urban Heat Island effect (UHI) and seeking to enhance the outdoor thermal comfort. The comparison between DART modelled and field estimated Tmrt shows good agreement in our study site under clear-sky condition over a time period from 10:00 to 19:00 (R2 = 0.9697, RMSE = 3.3249). The use of a 3-D radiative transfer model shows promising capability to study urban microclimate and outdoor thermal comfort with increasing landscape details, and to build linkage to remote sensing data. Our methodology has the potential to contribute towards optimizing climate-sensitive urban design when combined with the appropriate tools.

scholarly journals How Can We Adapt Thermal Comfort for Disabled Patients? A Case Study of French Healthcare Buildings in Summer

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4530
Author(s):  
Youcef Bouzidi ◽  
Zoubayre El Akili ◽  
Antoine Gademer ◽  
Nacef Tazi ◽  
Adil Chahboun
Keyword(s):  
Thermal Comfort ◽  
Thermal Environment ◽  
Residential Buildings ◽  
Linear Regression Analysis ◽  
Environmental Parameters ◽  
Physical Parameters ◽  
Mean Radiant Temperature ◽  
Operative Temperature ◽  
Neutral Temperature ◽  
Radiant Temperature

This paper investigates adaptive thermal comfort during summer in medical residences that are located in the French city of Troyes and managed by the Association of Parents of Disabled Children (APEI). Thermal comfort in these buildings is evaluated using subjective measurements and objective physical parameters. The thermal sensations of respondents were determined by questionnaires, while thermal comfort was estimated using the predicted mean vote (PMV) model. Indoor environmental parameters (relative humidity, mean radiant temperature, air temperature, and air velocity) were measured using a thermal environment sensor during the summer period in July and August 2018. A good correlation was found between operative temperature, mean radiant temperature, and PMV. The neutral temperature was determined by linear regression analysis of the operative temperature and Fanger’s PMV model. The obtained neutral temperature is 23.7 °C. Based on the datasets and questionnaires, the adaptive coefficient α representing patients’ capacity to adapt to heat was found to be 1.261. A strong correlation was also observed between the sequential thermal index n(t) and the adaptive temperature. Finally, a new empirical model of adaptive temperature was developed using the data collected from a longitudinal survey in four residential buildings of APEI in summer, and the obtained adaptive temperature is 25.0 °C with upper and lower limits of 24.7 °C and 25.4 °C.

scholarly journals A climatic study of an urban green space: the Gulbenkian Park in Lisbon (Portugal)

Finisterra ◽  
2012 ◽  
Vol 42 (84) ◽  
Author(s):  
Henrique Andrade ◽  
Rute Vieira
Keyword(s):  
Solar Radiation ◽  
Thermal Comfort ◽  
Green Space ◽  
Urban Green Space ◽  
Mean Radiant Temperature ◽  
Climatic Parameters ◽  
Incident Solar Radiation ◽  
Urban Green ◽  
Isolated Trees ◽  
Radiant Temperature

Measurements of various climatic parameters were carried out in an average-sized green space in the centre of Lisbon (the Fundação Calouste Gulbenkian Park). The aims consisted of assessing the thermal differentiation between the park and the surrounding built-up area and analysing the microclimatic patterns within the park itself. The main results demonstrate that the park is cooler than the built-up area in all the seasons and both during the daytime and at night, but especially so in the daytime during the summer. The most significant microclimatic contrasts were found to occur with respect to solar radiation and mean radiant temperature, with consequences upon the level of thermal comfort. The structure of the vegetation was also found to have a significant microclimatic influence, since the reduction in the level of incident solar radiation brought on by the presence of groups of trees was much larger than that associated with isolated trees.

scholarly journals The most problematic variable in the course of human-biometeorological comfort assessment — the mean radiant temperature

2011 ◽  
Vol 3 (1) ◽  
Author(s):  
Noémi Kántor ◽  
János Unger
Keyword(s):  
Thermal Comfort ◽  
Short Wave ◽  
Urban Environments ◽  
Outdoor Thermal Comfort ◽  
Radiation Environment ◽  
Wave Radiation ◽  
Mean Radiant Temperature ◽  
Radiation Fluxes ◽  
The Mean ◽  
Radiant Temperature

AbstractThis paper gives a review on the topic of the mean radiant temperature Tmrt, the most important parameter influencing outdoor thermal comfort during sunny conditions. Tmrt summarizes all short wave and long wave radiation fluxes reaching the human body, which can be very complex (variable in spatial and also in temporal manner) in urban settings. Thermal comfort researchers and urban planners need easy and sound methodological approaches to assess Tmrt. After the basics of the Tmrt calculation some of the methods suitable for obtaining Tmrt also in urban environments will be presented.. Two of the discussed methods are based on instruments which measure the radiation fluxes integral (globe thermometer, pyranometer-pyrgeometer combination), and three of the methods are based on modelling the radiation environment with PC software (RayMan, ENVI-met and SOLWEIG).

scholarly journals Accuracy of Mean Radiant Temperature Derived from Active and Passive Radiometry

Atmosphere ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 805
Author(s):  
Henning Staiger ◽  
Andreas Matzarakis
Keyword(s):  
Cross Section ◽  
Radiant Heat ◽  
Energy Balance Equation ◽  
Mean Radiant Temperature ◽  
Thermal Indices ◽  
Solar Altitude ◽  
Spectral Bands ◽  
Actual Environment ◽  
A Minor ◽  
Radiant Temperature

The concept of the mean radiant temperature (Tmrt) allows the study of radiative exchanges between a human and its environment. It presupposes that the radiant effects on the person of the actual environment, which is generally heterogeneous, and the virtual environment, which is defined as homogeneous, are identical. ISO 7726 specifies the required accuracy in Tmrt as input of rational thermal indices, outdoors ±5 (K). Tmrt accounts for the radiant heat absorbed by skin/clothing from the shortwave (SW) and longwave (LW) spectral bands. Most of the radiant components are isotropic. However, there are anisotropic SW components; namely the direct irradiance and under clear or partly obstructed skies a significant circumsolar fraction (fcs) in the diffuse irradiance. Both originate from the close proximity of the solar disk. This study highlights the effect of fcs on Tmrt. In the scope of human biometeorology a standing body posture is standard. For unidirectional irradiances its radiant cross-section varies dependent on the solar altitude. Active radiometry in deriving Tmrt is based on measured irradiances. One method is the Klima-Michel-Modell (KMM) that uses readily available measurements from standard meteorologically radiant observations. KMM references Fanger’s area projection factors that are derived from precise measurements of real humans. Thus, KMM serves as reference in evaluation of further methods. One is the six-directional instrument (Tmrt,r,6−Dir). Slightly simplifying a standing human, it represents a subject as a rectangular solid. Tmrt,r,6−Dir is derived based on measured irradiances incident on the vertical and horizontal planes. In passive radiometry the energy balance equation of a black globe thermometer is solved that leads to Tmrt,Tg,BG. fcs significantly impacts Tmrt with noticeably reduced values for high and increased for low solar altitudes. Hence, accounting for fcs is essential for the accuracy of Tmrt. For KMM an extension to an existing algorithm is provided in order to include fcs into the Tmrt calculation that results in Tmrt,r,KMM. For Tmrt,r,6−Dir the radiant cross-section of the solid depends to a minor extent on its azimuth relative to the solar azimuth. As a result Tmrt,r,6−Dir slightly scatters compared to Tmrt,r,KMM. However, it remains within ±2 (K). Tmrt,Tg,BG compared to Tmrt,r,KMM complies only at night with the ISO 7726 bin of ±5 K. Tmrt,Tg,BG significantly overestimates Tmrt,r,KMM during the daytime, because of its greater SW absorptance compared to skin/clothing and to a smaller extent because the standing posture is represented by a sphere. Particularly in sunny conditions, Tmrt,Tg,BG is subject to considerable variance. Thus, outdoors during the daytime, Tmrt,Tg,BG is unable to serve as an appropriate input for the calculation of rational-based thermal indices.

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