Modification of Human-Biometeorologically Significant Radiant Flux Densities by Shading as Local Method to Mitigate Heat Stress in Summer within Urban Street Canyons

Lee, Hyunjung; Holst, Jutta; Mayer, Helmut

doi:10.1155/2013/312572

Cited by 121 publications

(67 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In addition, vegetation as a microclimatic optimizer works perfectly in conjunction with trees in contrast to being implemented solely. This statement is verified by many studies which mainly concentrate on the importance as well as the effects of vegetation on regulating Tmrt and PET (Ali- (Lee, Holst, & Mayer, 2013) (Hisarligil, 2013) (Makaremi, Salleh, Jaafar, & Ghaffarian Hoseini, 2012) (Yahia & Johansson, 2014) (Shashua-Bar, Pearlmutter, & Erell, 2009) (Robitu, Musy, Inard, & Groleau, 2006) (Christopoulou, Tsiros, Hoffman, & Tseliou, 2015) (Chen & Ng, 2013) (Lin, Matzarakis, & Hwang, 2010) [61-70]. Taleghani's et al ) study which is conducted in a temperate climate discusses different approaches for decreasing absorbed solar radiation such as geometrical parameters (orientation and overall configuration), vegetation, using surfaces with higher albedo and water pools.…”

Section: Introductionmentioning

confidence: 59%

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

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionmentioning

confidence: 59%

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

View full text Add to dashboard Cite

show abstract

“…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%

“…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%

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

Lin

Tsai

2017

Sustainability

View full text Add to dashboard Cite

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.

show abstract

“…SVF is relevant to human thermal comfort, as it affects Mean Radiant Temperature (MRT), a synthetic parameter that summarizes the direct and reflected short and longwave radiation fluxes a human body is exposed to. MRT is one of the most important meteorological variables in the assessment of thermal comfort and the basis for many human thermal comfort indices (Johansson, Thorsson, Emmanuel, & Krüger, 2014;Lee, Holst, & Mayer, 2013;Thorsson, Lindberg, Eliasson, & Holmer, 2007).…”

Section: Introductionmentioning

confidence: 99%

Sky View Factors from Synthetic Fisheye Photos for Thermal Comfort Routing—A Case Study in Phoenix, Arizona

Middel

Lukasczyk

Maciejewski

2017

View full text Add to dashboard Cite

The Sky View Factor (SVF) is a dimension-reduced representation of urban form and one of the major variables in radiation models that estimate outdoor thermal comfort. Common ways of retrieving SVFs in urban environments include capturing fisheye photographs or creating a digital 3D city or elevation model of the environment. Such techniques have previously been limited due to a lack of imagery or lack of full scale detailed models of urban areas. We developed a web based tool that automatically generates synthetic hemispherical fisheye views from Google Earth at arbitrary spatial resolution and calculates the corresponding SVFs through equiangular projection. SVF results were validated using Google Maps Street View and compared to results from other SVF calculation tools. We generated 5-meter resolution SVF maps for two neighborhoods in Phoenix, Arizona to illustrate fine-scale variations of intra-urban horizon limitations due to urban form and vegetation. To demonstrate the utility of our synthetic fisheye approach for heat stress applications, we automated a radiation model to generate outdoor thermal comfort maps for Arizona State University's Tempe campus for a hot summer day using synthetic fisheye photos and on-site meteorological data. Model output was tested against mobile transect measurements of the six-directional radiant flux density. Based on the thermal comfort maps, we implemented a pedestrian routing algorithm that is optimized for distance and thermal comfort preferences. Our synthetic fisheye approach can help planners assess urban design and tree planting strategies to maximize thermal comfort outcomes and can support heat hazard mitigation in urban areas.

show abstract

Modification of Human-Biometeorologically Significant Radiant Flux Densities by Shading as Local Method to Mitigate Heat Stress in Summer within Urban Street Canyons

Cited by 121 publications

References 40 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

Sky View Factors from Synthetic Fisheye Photos for Thermal Comfort Routing—A Case Study in Phoenix, Arizona

Contact Info

Product

Resources

About