Human body area factors for radiation exchange analysis: standing and walking postures

Park, Sookuk; Tuller, Stanton E.

doi:10.1007/s00484-010-0385-2

Cited by 27 publications

(9 citation statements)

References 23 publications

(37 reference statements)

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“…In the MRT calculation, the solar radiation absorptance of the clothed human body was set at 0.66 for the summer season, according to Watanabe et al (2013). In addition, the human projection area factor due to direct solar radiation was applied to the equation for walking (Park and Tuller, 2011). The effective radiation area factor was set to be 0.91 for a clothed and standing human body (Horikoshi et al, 1990).…”

Section: Observation Daysmentioning

confidence: 99%

Outdoor thermal environment of a traditional settlement with a group of wooden storehouses in summer daytime at Tsushima Island, Japan

Hashimoto

Watanabe

2021

JHES

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Traditional settlements have been formed by adapting to local climate and natural features. This study aims to clarify the climatic characteristics of a settlement with a group of wooden storehouses in summer daytime from the viewpoint of environmental design. Waniura settlement in Tsushima Island, Japan was selected as the observation site of this study. The largest group of wooden storehouses in Tsushima Island is in Waniura settlement, and it is in the north of the settlement. About 150 storehouses are located near the port. The microclimate observations in the settlement and heat parameters measurements, including UV intensities at three representative points, were carried out in the summer of 2019. The wind direction in the northern part of the settlement had a different trend than that in the sky. The wind directions in Waniura settlement is affected by the topography when the wind in the sky blows in different directions from the valley line in the settlement. The layout of storehouses affects the wind environment of the group of wooden storehouses and the wind reducing effect appears when the wind blows orthogonally to the parallel storehouses. At the shaded path (point-C) on 1,000 W/m 2 global solar radiation, the MRT reduction was -25.7 °C. The reason the MRT at the shaded path dropped significantly was that the storehouses built close to each other blocked the solar radiation on the shaded path significantly. Furthermore, less solar radiation on the shaded path might contribute to maintaining the low surface temperatures of the pathway and the storehouses. At the shaded path on 1,000 W/m 2 global solar radiation, the UTCI reduction was -4.4 °C. This result emphasizes the importance of providing shade from buildings or other means and directing wind into those spaces to improve the outdoor thermal environment. At the shaded path in the group of wooden storehouses on 1000 W/m 2 global solar radiation, the UV Index reduction was -5.4. This large UV Index reduction at the shaded path can be because the storehouses were built close to each other, thus blocking most direct and diffuse components of UV radiation. It has become clear that a heat island appears in the centre of the settlement with a population of about 200 people in the daytime on a clear summer day. In contrast, the heat island did not appear in the group of wooden storehouses, despite the dense construction of storehouses. This is probably because the storehouse is a low-rise wooden building with low heat capacity and because there is no energy consumption or waste heat there. It is evident that the cooling effect of the group of storehouses on the radiant environment, thermal environment and UV environment appears in the summer daytime. Based on the results of the field observations, it has been empirically shown that it is an effective environmental design method for mitigating the thermal environment in the summer daytime by composing a group of low-rise wooden buildings is concerned with taking into account their ventilation.

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Section: Observation Daysmentioning

confidence: 99%

Outdoor thermal environment of a traditional settlement with a group of wooden storehouses in summer daytime at Tsushima Island, Japan

Hashimoto

Watanabe

2021

JHES

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“…Another method for determining Tmrt using observed irradiances is the six-directional instrument (Tmrt,r,6-Dir (K)) that posits the subject concerned as a rectangular solid [1,15]. This Tmrt,r,6-Dir (K) is also defined as the plane radiant temperature [8,9], however using pyranometers and pyrgeometers facing [12] and Park and Tuller [11] for the reference subject and additionally for a cylinder and a globe.…”

Section: Six-direction Instrumentmentioning

confidence: 99%

“…f p = A p /A eff relates the projected area of a person A p to its effective radiant area A eff , i.e., the total surface of the person minus that area parts that overlap, e.g., arms and trunk. Thus, f p is a function of the body posture and the elevation angle [6,10,11] and is precisely determined by the shadow area of the irradiated person on a plane normal to the direction of the incident beam. As the sum of the angle factors is unity, the fourth power of T mrt will be seen to be equal to the mean value of the surrounding surface temperatures to the fourth power, weighted with the respective angle factors [6].…”

Section: Introductionmentioning

confidence: 99%

“…In applied human biometeorology an upright reference subject is used that is rotationally symmetric to its vertical axis because the azimuthal orientation of the subject is usually unknown. Its elevation dependent f p is derivable from diagrams and tables [1,6,11]. Because only the fraction of radiant energy that is absorbed by the skin/clothing surface can have an effect on the human energy balance, the clothing/skin of the reference subject is assumed to show overall SW absorption (α sw,Sk ) of 0.70 and LW emissivity (ε lw,Sk ) of 0.97 that is identical with its absorptivity (Kirchhoff law) [1,8,9].…”

Section: Introductionmentioning

confidence: 99%

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Accuracy of Mean Radiant Temperature Derived from Active and Passive Radiometry

Staiger

Matzarakis

2020

Atmosphere

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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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“…Vernez et al (2011) used a numeric model of 3D human to simulate an individual's solar ultraviolet exposure and then calculated the anatomical exposure patterns of the skin (Vernez et al 2012). Some researchers used human models to study the relation of body postures, solar elevation, and azimuth angles (Kubaha et al 2004;Park and Tuller 2011). Seckmeyer et al (2013) used a mathematical method to calculate vitD-weighted exposure via integration of the incident solar spectral irradiance over all relevant parts of the human body.…”

Section: Introductionmentioning

confidence: 99%

The angular distributions of ultraviolet spectral irradiance at different solar elevation angles under clear sky conditions

Liu

Wang

et al. 2015

Int J Biometeorol

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To investigate the angular distributions of UVA, UVB, and effective UV for erythema and vitamin D (vitD) synthesis, the UV spectral irradiances were measured at ten inclined angles (from 0° to 90°) and seven azimuths (from 0° to 180°) at solar elevation angle (SEA) that ranged from 18.8° to 80° in Shanghai (31.22° N, 121.55° E) under clear sky and the albedo of ground was 0.1. The results demonstrated that in the mean azimuths and with the back to the sun, the UVA, UVB, and erythemally and vitD-weighted irradiances increased with the inclined angles and an increase in SEA. When facing toward the sun at 0°-60° inclined angles, the UVA first increased and then decreased with an increase in SEA; at other inclined angles, the UVA increased with SEA. At 0°-40° inclined angles, the UVB and erythemally and vitD-weighted irradiances first increased and then decreased with an increase in SEA, and their maximums were achieved at SEA 68.7°; at other inclined angles, the above three irradiances increased with an increase in SEA. The maximum UVA, UVB, and erythemally and vitD-weighted irradiances were achieved at an 80° inclined angle at SEA 80° (the highest in our measurements); the cumulative exposure of the half day achieved the maximum at a 60° inclined angle, but not on the horizontal. This study provides support for the assessment of human skin sun exposure.

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Human body area factors for radiation exchange analysis: standing and walking postures

Cited by 27 publications

References 23 publications

Outdoor thermal environment of a traditional settlement with a group of wooden storehouses in summer daytime at Tsushima Island, Japan

Outdoor thermal environment of a traditional settlement with a group of wooden storehouses in summer daytime at Tsushima Island, Japan

Accuracy of Mean Radiant Temperature Derived from Active and Passive Radiometry

The angular distributions of ultraviolet spectral irradiance at different solar elevation angles under clear sky conditions

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