Importance of 3-D radiant flux densities for outdoor human thermal comfort on clear-sky summer days in Freiburg, Southwest Germany

Lee, Hyunjung; Mayer, Helmut; Schindler, Dirk

doi:10.1127/0941-2948/2014/0536

Cited by 78 publications

(34 citation statements)

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“…In some of these studies, the significance of 3D Radiant Flux Densities and its impact on Tmrt, PET and temperature is discussed and they indicate change of Tmrt and Radiant Flux Densities of long and short wavelengths are of high importance (Holst, Dostal, Imbery, & Mayer, 2009) (Mayer, Kuppe, Holst, & Matzarakis, 2009). In general, the magnitude of Tmrt is shown through 3D Radiant Flux Densities with long wavelength while its fluctuation is dependent on short wavelength (Lee, Mayer, & Schindler, 2014) (Ali- . For instance, the short wavelength effects on changes of Tmrt is about 10% under shadow and 29% in locations without shadow (Mayer, Kuppe, Holst, & Matzarakis, 2009).…”

Section: Introductionmentioning

confidence: 99%

Numerical evaluation of thermal comfort in traditional courtyards to develop new microclimate design in a hot and dry climate

Nasrollahi

Hatami

Khastar

et al. 2017

Sustainable Cities and Society

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The growing interest in thermal comfort of outdoor environments yields in different analysis on courtyards as a common space between urban and architectural scales. However, there is a limited knowledge regarding the microclimatic behavior of such spaces. Using ENVI-met simulations, this paper aims to numerically discuss the thermal performance of different configurations of traditionally designed courtyards in Shiraz, Iran, which experiences hot summers and cold winters. The geometrical effects such as orientation and H/W (height to width ratio) of courtyards are considered as potential parameters to improve the microclimatic conditions. In this paper, PMV and UTCI are used as thermal comfort indices.The obtained results indicate mean radiant temperature and wind speed as the most effective parameters for thermal comfort of courtyards. In addition, the aforementioned geometrical parameters might not be able to solely create a desirable condition, but they could significantly improve the thermal comfort of courtyards during summer and winter. To achieve a desirable thermal comfort level, the results suggest using configurations of a high H/W rate and southward orientation in order to obtain better shading during summer as well as allowing the solar radiation in while regulating the wind speed in winter.

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Section: Introductionmentioning

confidence: 99%

Numerical evaluation of thermal comfort in traditional courtyards to develop new microclimate design in a hot and dry climate

Nasrollahi

Hatami

Khastar

et al. 2017

Sustainable Cities and Society

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show abstract

“…In European countries and Hong Kong, wind has a negative effect on thermal sensation, and high wind speed only becomes significant in thermal sensation in winter [19,20]. The sky view factor (SVF) describes the impact of canopy density on air circulation [8] and the irradiance reduction of plant canopies [9,10,21]. Because SVF can be measured conveniently, some studies have used SVF to discuss variations in shading levels and air temperature [22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

“…A favorable tree planting design provides appropriate shade and cooling functions [2][3][4][5]. These functions not only influence microclimate modification, especially for tropical and subtropical regions [6][7][8], but also improve thermal comfort [9][10][11]. For example, the structures of tree crowns, and the shapes and colors of the leaves, influence the levels of visible light and solar infrared waves [6].…”

Section: Introductionmentioning

confidence: 99%

Screening of Tree Species for Improving Outdoor Human Thermal Comfort in a Taiwanese City

Lin

Tsai

2017

Sustainability

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Tropical cities can use urban greening designs featuring trees that provide shade and cooling in hot outdoor environments. The cooling effect involves numerous tree characteristics that are not easy to control during planting design, such as the canopy size and the optical properties of leaves. Planting the appropriate tree species dominates the cooling effects and the human thermal environment. Based on environmental and plant data, including the tree species, crown diameter of trees, physiologically equivalent temperature (PET), and sky view factor (SVF) in an outdoor space, a series of hierarchical cluster analysis (HCA) procedures was implemented to identify the tree species that are appropriate for improving thermal comfort. The results indicated strong correlations between SVF, average crown diameter, and PET. SVF decreased as the average crown diameter increased. For the average crown diameter of trees in an area wider than 1.5 m, the cooling effect was especially dominated by the tree species. Therefore, 15 species were screened by HCA procedures, based on a similar cooling effect. These species had various cooling effects, and were divided into four categories. Tree species, such as Spathodea campanulata and Cinnamomum camphora, had the appropriate crown diameter and cooling effect for the most comfortable thermal environment.

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“…Under Central-European climate conditions, extreme heat stress at the street level is usually the effect of high solar radiation and the resulting high radiation budget of pedestrians (eg. Gulyás, Unger, 2010;Kántor, Unger, 2011;Égerházi, et al, 2013;Lee, et al, 2014). Carefully designed shading is therefore essential in the fight against heat stress and in the creation of comfortable outdoor places (Lee, et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Solar permeability of different tree species in Szeged, Hungary

Takács¹,

Kiss²,

Gulyás³

et al. 2016

Geogr Pannon

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The heat stress modification capacity of urban trees is widely acknowledged and makes these natural landscape elements very important in the field of climate conscious urban planning. Many studies proved that shading, i.e. the reduction of direct solar radiation is the most effective way to moderate summer heat stress under Central European climatic conditions. The investigation aims at determining the transmissivity of four tree species that occur frequently in Hungarian cities: Sophora japonica, Tilia cordata, Celtis occidentalis and Aesculus hippocastanum. In order to accomplish that, a systematic radiation measurement campaign was carried out in the South-Hungarian city of Szeged, from early summer (foliated condition of trees) to late autumn (nearly leafless condition). Short-wave radiation from the upper hemisphere was measured with Kipp & Zonen pyranometers under carefully selected tree specimens (transmitted radiation), as well as on a roof station free from sky obstruction (actual value of global radiation). The calculated transmissivity values varied greatly with the seasonal status of the canopy (the median value of transmissivity increased from 0.03 to 0.47 in case of A. hippocastanum), and we found considerable inter-species differences too, evidencing that solar permeability depends on the amount of leaves, leaf density and other tree crown-related characteristics.

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Importance of 3-D radiant flux densities for outdoor human thermal comfort on clear-sky summer days in Freiburg, Southwest Germany

Cited by 78 publications

References 0 publications

Numerical evaluation of thermal comfort in traditional courtyards to develop new microclimate design in a hot and dry climate

Numerical evaluation of thermal comfort in traditional courtyards to develop new microclimate design in a hot and dry climate

Screening of Tree Species for Improving Outdoor Human Thermal Comfort in a Taiwanese City

Solar permeability of different tree species in Szeged, Hungary

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