The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Andreas Matzarakis - One of the best experts on this subject based on the ideXlab platform.
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Reduction of Mean Radiant Temperature by Cluster of Trees In Urban and Architectural Planning In Tropical Climates
2020Co-Authors: Loyde Vieira De Abreu-harbich, Lucila Chebel Labaki, Andreas MatzarakisAbstract:This paper presents thermal bioclimate analyses using air Temperature, mean Radiant Temperature and physiologically equivalent Temperature conditions in tropical climate of Campinas, Brazil, and also, the influence of solar radiation attenuated by shade clusters in mean Radiant Temperature . Six homogeneous clusters of trees were chosen: Caesalpinia pluviosa, Spathodea campanulata, Tipuana tipu, Lafoensia glyptocarpa, Delonix indica, Senna siamea. The data collected in field measurement were: solar radiation, air Temperatures, relative humidity and wind speed, for the period 2007 to 2010. The simulation of shade variation were done for the period 2003 to 2010 over to verify the influence on urban climate changes in mean Temperature due modifications tree canopy. The results shows not only that solar radiation can influence air Temperature, but also mean Radiant Temperature as well. Furthermore, the simulation of shade variation conditions demonstrates that the shade clusters of trees can reduce the mean Radiant Temperature. Percentages of solar radiation reduction by cluster of trees as Caesalpinia peltophoroides (deciduous) have the best results, shows that canopy provides shadow, reduces the mean Radiant Temperature and also, improve the thermal bioclimate in micro scale conditions.
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Mean Radiant Temperature in urban canyons from solar calculations, climate and surface properties – Theory, validation and ʽMr.Tʼ software
Building and Environment, 2020Co-Authors: Shabtai Cohen, Andreas Matzarakis, Yaniv Palatchi, Danielle Potchter Palatchi, Limor Shashua-bar, Victor Lukyanov, Yaron Yaakov, Josef Tanny, Oded PotchterAbstract:Abstract Mean Radiant Temperature (Tmrt) is important for human thermal comfort indexes, but is difficult to determine. Tmrt was calculated from measured Temperatures of buildings and vegetation surfaces in urban scenarios along with meteorological data (Temperature, relative humidity and global radiation). The method can be used for experimental work in the urban settings without the use of four-flux net radiometers. Differences in Tmrt for different positions in the urban canyon can be calculated. A software package named Mr.T was developed which allows determining Tmrt from data input manually or from EXCEL spreadsheets. The software was validated in two urban settings: in Tel Aviv University and a nearby urban canyon in summer and in the old city quarter of Beer Sheva at the end of winter. Results were close to those obtained with a four-flux net radiometer. Differences in calculated and measured fluxes are discussed as well as sources of errors in the calculations. Assumption of clear skies for the computation of atmospheric radiation did not introduce significant errors. A priori values of albedo and emissivity of the different urban surfaces can have large effects on fluxes and Radiant Temperatures, and the use of tables of those values is probably a large source of uncertainty when using the calculation procedure. In conclusion, the software developed can be a significant tool for the study of thermal comfort conditions in urban settings.
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mean Radiant Temperature in urban canyons from solar calculations climate and surface properties theory validation and ʽmr tʼ software
Building and Environment, 2020Co-Authors: Shabtai Cohen, Andreas Matzarakis, Yaniv Palatchi, Danielle Potchter Palatchi, Victor Lukyanov, Yaron Yaakov, Josef Tanny, Limor Shashuabar, Oded PotchterAbstract:Abstract Mean Radiant Temperature (Tmrt) is important for human thermal comfort indexes, but is difficult to determine. Tmrt was calculated from measured Temperatures of buildings and vegetation surfaces in urban scenarios along with meteorological data (Temperature, relative humidity and global radiation). The method can be used for experimental work in the urban settings without the use of four-flux net radiometers. Differences in Tmrt for different positions in the urban canyon can be calculated. A software package named Mr.T was developed which allows determining Tmrt from data input manually or from EXCEL spreadsheets. The software was validated in two urban settings: in Tel Aviv University and a nearby urban canyon in summer and in the old city quarter of Beer Sheva at the end of winter. Results were close to those obtained with a four-flux net radiometer. Differences in calculated and measured fluxes are discussed as well as sources of errors in the calculations. Assumption of clear skies for the computation of atmospheric radiation did not introduce significant errors. A priori values of albedo and emissivity of the different urban surfaces can have large effects on fluxes and Radiant Temperatures, and the use of tables of those values is probably a large source of uncertainty when using the calculation procedure. In conclusion, the software developed can be a significant tool for the study of thermal comfort conditions in urban settings.
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Modeling of mean Radiant Temperature based on comparison of airborne remote sensing data with surface measured data
Atmospheric Research, 2016Co-Authors: Yu Cheng Chen, Chih Yu Chen, Andreas MatzarakisAbstract:Abstract Assessment of outdoor thermal comfort is becoming increasingly important due to the urban heat island effect, which strongly affects the urban thermal environment. The mean Radiant Temperature (Tmrt) quantifies the effect of the radiation environment on humans, but it can only be estimated based on influencing parameters and factors. Knowledge of Tmrt is important for quantifying the heat load on human beings, especially during heat waves. This study estimates Tmrt using several methods, which are based on climatic data from a traditional weather station, microscale ground surface measurements, land surface Temperature (LST) and light detection and ranging (LIDAR) data measured using airborne devices. Analytical results reveal that the best means of estimating Tmrt combines information about LST and surface elevation information with meteorological data from the closest weather station. The application in this method can eliminate the inconvenience of executing a wide range ground surface measurement, the insufficient resolution of satellite data and the incomplete data of current urban built environments. This method can be used to map a whole city to identify hot spots, and can be contributed to understanding human biometeorological conditions quickly and accurately.
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daytime relapse of the mean Radiant Temperature based on the six directional method under unobstructed solar radiation
International Journal of Biometeorology, 2014Co-Authors: Noemi Kantor, Andreas MatzarakisAbstract:This study contributes to the knowledge about the capabilities of the popular “six-directional method” describing the radiation fields outdoors. In Taiwan, measurements were carried out with three orthogonally placed net radiometers to determine the mean Radiant Temperature (T mrt). The short- and long-wave radiation flux densities from the six perpendicular directions were recorded in the daylight hours of 12 days. During unobstructed direct irradiation, a specific daytime relapse was found in the temporal course of the T mrt values referring to the reference shapes of a standing man and also of a sphere. This relapse can be related to the short-wave fluxes reaching the body from the lateral directions. Through deeper analysis, an instrumental shortcoming of the six-directional technique was discovered. The pyranometer pairs of the same net radiometer have a 10–15-min long “blind spot” when the sun beams are nearly perpendicular to them. The blind-spot period is supposed to be shorter with steeper solar azimuth curve on the daylight period. This means that the locations with lower geographical latitude, and the summertime measurements, are affected less by this instrumental problem. A methodological shortcoming of the six-directional technique was also demonstrated. Namely, the sum of the short-wave flux densities from the lateral directions is sensitive to the orientation of the radiometers, and therefore by deviating from the original directions, the T mrt decrease on clear sunny days will occur in different times and will be different in extent.
Steve Kardinal Jusuf - One of the best experts on this subject based on the ideXlab platform.
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effects of vertical greenery on mean Radiant Temperature in the tropical urban environment
Landscape and Urban Planning, 2014Co-Authors: Nyuk Hien Wong, Steve Kardinal JusufAbstract:Abstract Studies on vertical greenery generally focus on the measurement of air Temperature, surface Temperature and cooling load. There is a lack of information on how vertical greenery can influence outdoor thermal comfort. The objective of this study is to quantify the effects of mean Radiant Temperature ( t mrt ), as the first step towards determining the thermal quality of outdoor space due to installation of vertical greenery. The t mrt of two green walls (Green Wall A and Green Wall B) was measured up to 2 m away at intervals of 0.5 m. Two datasets were obtained, one consisting of t mrt , surface and air Temperature collected from the two green walls and the second for just green wall A and the exposed concrete wall after Green Wall B was removed. t mrt was measured using customised globe thermometers calibrated for local use. Data was analysed using a GIS, thus enabling convenient visual comparison between t mrt profiles at different times. The diurnal t mrt profile was altered significantly due to the installation of vertical greenery. When both green walls were present the peak t mrt occurred at 15:00 h, but with more concrete exposed when one wall was removed, the peak occurred at 17:00 h and was 10.9–12.9° higher at 0.5 m away from the wall. Vertical greenery thus helped to reduce t mrt both during the day and at night, to varying extents. The proposed methodology enables systematic quantification of the effects of vertical greenery on t mrt .
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Effects of vertical greenery on mean Radiant Temperature in the tropical urban environment
Landscape and Urban Planning, 2014Co-Authors: Chun Liang Tan, Nyuk Hien Wong, Steve Kardinal JusufAbstract:Studies on vertical greenery generally focus on the measurement of air Temperature, surface Temperature and cooling load. There is a lack of information on how vertical greenery can influence outdoor thermal comfort. The objective of this study is to quantify the effects of mean Radiant Temperature (tmrt), as the first step towards determining the thermal quality of outdoor space due to installation of vertical greenery.The tmrtof two green walls (Green Wall A and Green Wall B) was measured up to 2m away at intervals of 0.5m. Two datasets were obtained, one consisting of tmrt, surface and air Temperature collected from the two green walls and the second for just green wall A and the exposed concrete wall after Green Wall B was removed. tmrtwas measured using customised globe thermometers calibrated for local use. Data was analysed using a GIS, thus enabling convenient visual comparison between tmrtprofiles at different times. The diurnal tmrtprofile was altered significantly due to the installation of vertical greenery. When both green walls were present the peak tmrtoccurred at 15:00h, but with more concrete exposed when one wall was removed, the peak occurred at 17:00h and was 10.9-12.9° higher at 0.5m away from the wall. Vertical greenery thus helped to reduce tmrtboth during the day and at night, to varying extents. The proposed methodology enables systematic quantification of the effects of vertical greenery on tmrt. © 2014 Elsevier B.V.
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outdoor mean Radiant Temperature estimation in the tropical urban environment
Building and Environment, 2013Co-Authors: Nyuk Hien Wong, Steve Kardinal JusufAbstract:Abstract A large scale estimation of mean Radiant Temperature (tmrt) is conducted at two sites using customised globe thermometers. The measurement points cover a variety of urban typologies such as high-rise offices, parks, large water bodies and housing apartments. Data is derived using a tmrt formula calibrated to the local climate. Measurements for clear, sunny days are used for the analysis of the average diurnal tmrt profile. The diurnal tmrt profile shows that the tmrt differential between points is most evident during daytime, and is affected most significantly by shade cast by trees and buildings. Results also show that common urban constituents such as greenery and large water bodies, while proven to effectively reduce the ambient Temperature of its surroundings throughout the day, do not affect tmrt significantly after nightfall. Further analysis reveals a correlation between sky view factor and tmrt in the day. Measurement points in different parks exhibit contrasting trends in tmrt reduction. Results of the study also provide a realistic threshold for the lowering of outdoor tmrt. Trees, shrubs and green walls may be introduced into the outdoor environment with the intention of reducing tmrt to a desirable level for a specific time range.
Fredrik Lindberg - One of the best experts on this subject based on the ideXlab platform.
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SOLWEIG - The new model for calculating the mean Radiant Temperature
2020Co-Authors: Fredrik Lindberg, Sofia ThorssonAbstract:The new radiation model, SOLWEIG (SOlar and LongWave Environmental Irradiance Geometry-model), which simulates three-dimensional daytime short-wave and long-wave radiation fluxes as well as mean Radiant Temperature (Tmrt) in complex urban settings is presented in this paper. It is a grid based, non-stationary model that is able to compute spatial variations of radiation fluxes and Tmrt on very large model domains and on various temporal scales. The first version of the SOLWEIG model (1.0) uses built structures for representing urban geometry. In the second version (2.0) a vegetation scheme that is able to account for the radiative properties of trees and bushes which affects the outcome of the radiation fluxes and hence Tmrt will be included. Work on setting up a user-friendly interface for model runs is also demonstrated.
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The influence of anisotropic diffuse shortwave radiation on mean Radiant Temperature in outdoor urban environments
urban climate, 2020Co-Authors: Nils Wallenberg, Fredrik Lindberg, Bjorn Holmer, Sofia ThorssonAbstract:Abstract During clear weather conditions the main part of the shortwave irradiance derives from sun direct-beam radiation. However, part of the shortwave radiation also originates from all-sky diffuse radiation (D), with a large part being circumsolar in origin. Many radiation models considers the sky as isotropic when estimating D. Here we implement an anisotropic model for D into the SOLWEIG model to examine the spatial patterns of D in a built-up environment, as well as its influence on mean Radiant Temperature (Tmrt), a variable essential for estimating outdoor human thermal comfort. Comparisons between the anisotropic and the isotropic models indicates that the D in the isotropic model is overestimated in shaded areas and underestimated in areas close to sunlit walls. This is explained by the circumsolar origin of D during clear and semi-cloudy conditions and solar altitude. These over- and underestimations, consecutively, have implications for Tmrt, which can differ by up to 3 °C. The deviations in D thus signify the importance of using an anisotropic model when estimating D and Tmrt, especially since the areas with the highest reported Radiant loads receive even more radiation considering an anisotropic diffuse sky, i.e. the hottest areas are even hotter than previously reported.
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Present and projected future mean Radiant Temperature for three European cities
International Journal of Biometeorology, 2017Co-Authors: Sofia Thorsson, Fredrik Lindberg, Janina Konarska, David Rayner, Ana Monteiro, Lutz Katzschner, Sabrina Campe, Antje Katzschner, Shiho Onomura, Sara VelhoAbstract:Present-day and projected future changes in mean Radiant Temperature, T _mrt in one northern, one mid-, and one southern European city (represented by Gothenburg, Frankfurt, and Porto), are presented, and the concept of hot spots is adopted. Air Temperature, T _ a , increased in all cities by 2100, but changes in solar radiation due to changes in cloudiness counterbalanced or exacerbated the effects on T _mrt. The number of days with high T _mrt in Gothenburg was relatively unchanged at the end of the century (+1 day), whereas it more than doubled in Frankfurt and tripled in Porto. The use of street trees to reduce daytime Radiant heat load was analyzed using hot spots to identify where trees could be most beneficial. Hot spots, although varying in intensity and frequency, were generally confined to near sunlit southeast-southwest facing walls, in northeast corner of courtyards, and in open spaces in all three cities. By adding trees in these spaces, the Radiant heat load can be reduced, especially in spaces with no or few trees. A set of design principles for reducing the Radiant heat load is outlined based on these findings and existing literature.
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towards city wide building resolving analysis of mean Radiant Temperature
urban climate, 2016Co-Authors: Britta Janicke, Fredrik Lindberg, Fred Meier, Sebastian Schubert, Dieter SchererAbstract:Abstract This study presents a method to simulate Tmrt building-resolving while considering both micro-scale urban structures and meso-scale atmospheric conditions. We extended the model SOLWEIG, one of the few methods to derive mean Radiant Temperature (Tmrt) building-resolved and city-wide, to include spatial patterns of meteorological input. Based on a day within an extreme heat event (2003) in Berlin, Germany, we examined the effect of the new method on Tmrt, which uses gridded meteorological input data from a mesoscale weather model, compared to a standard set-up using ungridded data. Results indicted a considerable effect of spatially resolved air Temperature (up to 3.2 K) during midnight. Furthermore, we detected high sensitivity of Tmrt to the partitioning of direct and diffuse short-wave radiation. The spatial pattern of Tmrt revealed that at midday the city centre exhibited low values compared to open areas. We conclude that considering meso-scale atmospheric conditions and urban structure for simulating Tmrt city-wide can lead to a more appropriate description of heat-stress hazards and might also be valuable for climate-sensitive urban planning.
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influence of ground surface characteristics on the mean Radiant Temperature in urban areas
International Journal of Biometeorology, 2016Co-Authors: Fredrik Lindberg, Shiho Onomura, C S B GrimmondAbstract:The effect of variations in land cover on mean Radiant Temperature (T mrt ) is explored through a simple scheme developed within the radiation model SOLWEIG. Outgoing longwave radiation is parameterised using surface Temperature observations on a grass and an asphalt surface, whereas outgoing shortwave radiation is modelled through variations in albedo for the different surfaces. The influence of ground surface materials on T mrt is small compared to the effects of shadowing. Nevertheless, altering ground surface materials could contribute to a reduction in T mrt to reduce the Radiant load during heat-wave episodes in locations where shadowing is not an option. Evaluation of the new scheme suggests that despite its simplicity it can simulate the outgoing fluxes well, especially during sunny conditions. However, it underestimates at night and in shadowed locations. One grass surface used to develop the parameterisation, with very different characteristics compared to an evaluation grass site, caused T mrt to be underestimated. The implications of using high temporal resolution (e.g. 15 minutes) meteorological forcing data under partly cloudy conditions are demonstrated even for fairly proximal sites.
Sofia Thorsson - One of the best experts on this subject based on the ideXlab platform.
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SOLWEIG - The new model for calculating the mean Radiant Temperature
2020Co-Authors: Fredrik Lindberg, Sofia ThorssonAbstract:The new radiation model, SOLWEIG (SOlar and LongWave Environmental Irradiance Geometry-model), which simulates three-dimensional daytime short-wave and long-wave radiation fluxes as well as mean Radiant Temperature (Tmrt) in complex urban settings is presented in this paper. It is a grid based, non-stationary model that is able to compute spatial variations of radiation fluxes and Tmrt on very large model domains and on various temporal scales. The first version of the SOLWEIG model (1.0) uses built structures for representing urban geometry. In the second version (2.0) a vegetation scheme that is able to account for the radiative properties of trees and bushes which affects the outcome of the radiation fluxes and hence Tmrt will be included. Work on setting up a user-friendly interface for model runs is also demonstrated.
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The influence of anisotropic diffuse shortwave radiation on mean Radiant Temperature in outdoor urban environments
urban climate, 2020Co-Authors: Nils Wallenberg, Fredrik Lindberg, Bjorn Holmer, Sofia ThorssonAbstract:Abstract During clear weather conditions the main part of the shortwave irradiance derives from sun direct-beam radiation. However, part of the shortwave radiation also originates from all-sky diffuse radiation (D), with a large part being circumsolar in origin. Many radiation models considers the sky as isotropic when estimating D. Here we implement an anisotropic model for D into the SOLWEIG model to examine the spatial patterns of D in a built-up environment, as well as its influence on mean Radiant Temperature (Tmrt), a variable essential for estimating outdoor human thermal comfort. Comparisons between the anisotropic and the isotropic models indicates that the D in the isotropic model is overestimated in shaded areas and underestimated in areas close to sunlit walls. This is explained by the circumsolar origin of D during clear and semi-cloudy conditions and solar altitude. These over- and underestimations, consecutively, have implications for Tmrt, which can differ by up to 3 °C. The deviations in D thus signify the importance of using an anisotropic model when estimating D and Tmrt, especially since the areas with the highest reported Radiant loads receive even more radiation considering an anisotropic diffuse sky, i.e. the hottest areas are even hotter than previously reported.
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Present and projected future mean Radiant Temperature for three European cities
International Journal of Biometeorology, 2017Co-Authors: Sofia Thorsson, Fredrik Lindberg, Janina Konarska, David Rayner, Ana Monteiro, Lutz Katzschner, Sabrina Campe, Antje Katzschner, Shiho Onomura, Sara VelhoAbstract:Present-day and projected future changes in mean Radiant Temperature, T _mrt in one northern, one mid-, and one southern European city (represented by Gothenburg, Frankfurt, and Porto), are presented, and the concept of hot spots is adopted. Air Temperature, T _ a , increased in all cities by 2100, but changes in solar radiation due to changes in cloudiness counterbalanced or exacerbated the effects on T _mrt. The number of days with high T _mrt in Gothenburg was relatively unchanged at the end of the century (+1 day), whereas it more than doubled in Frankfurt and tripled in Porto. The use of street trees to reduce daytime Radiant heat load was analyzed using hot spots to identify where trees could be most beneficial. Hot spots, although varying in intensity and frequency, were generally confined to near sunlit southeast-southwest facing walls, in northeast corner of courtyards, and in open spaces in all three cities. By adding trees in these spaces, the Radiant heat load can be reduced, especially in spaces with no or few trees. A set of design principles for reducing the Radiant heat load is outlined based on these findings and existing literature.
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the effect of urban geometry on mean Radiant Temperature under future climate change a study of three european cities
International Journal of Biometeorology, 2015Co-Authors: Fredrik Lindberg, David Rayner, Sofia ThorssonAbstract:Future anthropogenic climate change is likely to increase the air Temperature (T a ) across Europe and increase the frequency, duration and magnitude of severe heat stress events. Heat stress events are generally associated with clear-sky conditions and high T a , which give rise to high Radiant heat load, i.e. mean Radiant Temperature (T mrt ). In urban environments, T mrt is strongly influenced by urban geometry. The present study examines the effect of urban geometry on daytime heat stress in three European cities (Gothenburg in Sweden, Frankfurt in Germany and Porto in Portugal) under present and future climates, using T mrt as an indicator of heat stress. It is found that severe heat stress occurs in all three cities. Similar maximum daytime T mrt is found in open areas in all three cities despite of the latitudinal differences in average daytime T mrt . In contrast, dense urban structures like narrow street canyons are able to mitigate heat stress in the summer, without causing substantial changes in T mrt in the winter. Although the T mrt averages are similar for the north–south and east–west street canyons in each city, the number of hours when T mrt exceeds the threshold values of 55.5 and 59.4 °C—used as indicators of moderate and severe heat stress—in the north–south canyons is much higher than that in the east–west canyons. Using statistically downscaled data from a regional climate model, it is found that the study sites were generally warmer in the future scenario, especially Porto, which would further exacerbate heat stress in urban areas. However, a decrease in solar radiation in Gothenburg and Frankfurt reduces T mrt in the spring, while the reduction in T mrt is somewhat offset by increasing T a in other seasons. It suggests that changes in the T mrt under the future scenario are dominated by variations in T a . Nonetheless, the intra-urban differences remain relatively stable in the future. These findings suggest that dense urban structure can reduce daytime heat stress since it reduces the number of hours of high T mrt in the summer and does not cause substantial changes in average and minimum T mrt in the winter. In dense urban settings, a more diverse urban thermal environment is also preferred to compensate for reduced solar access in the winter. The extent to which the urban geometry can be optimized for the future climate is also influenced by local urban characteristics.
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mean Radiant Temperature a predictor of heat related mortality
urban climate, 2014Co-Authors: Sofia Thorsson, Fredrik Lindberg, Joacim Rocklov, Janina Konarska, Bjorn Holmer, Benedicte Dousset, David RaynerAbstract:Health studies have repeatedly used air Temperature (Ta), sometimes adjusted for humidity, when analyzing the impact of weather on mortality. The aim of this study is to highlight the importance of mean Radiant Temperature (Tmrt) and its impact on heat related mortality. Tmrt is an essential meteorological parameter that influences the thermal comfort (heat load) of humans. It is useful when assessing the impact of weather, especially heat, on people’s health. Tmrt is directly influenced by urban geometry and surface material, which also makes it a good measure to identify urban hot spots. The performance of models using Ta and Tmrt for daily mortality is compared for Stockholm County, Sweden. It is demonstrated that Tmrt models fit heat related mortality better than Ta models, which implies that health studies should consider using Tmrt rather than Ta. The use of Tmrt models allows us to determine more accurate thresholds for increased risks of heat related mortality, and thus to better identify adverse weather conditions and heat prone urban geometries. Such information is needed to implement heat-warning systems and mitigate harmful effects of heat stress.
Nyuk Hien Wong - One of the best experts on this subject based on the ideXlab platform.
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effects of vertical greenery on mean Radiant Temperature in the tropical urban environment
Landscape and Urban Planning, 2014Co-Authors: Nyuk Hien Wong, Steve Kardinal JusufAbstract:Abstract Studies on vertical greenery generally focus on the measurement of air Temperature, surface Temperature and cooling load. There is a lack of information on how vertical greenery can influence outdoor thermal comfort. The objective of this study is to quantify the effects of mean Radiant Temperature ( t mrt ), as the first step towards determining the thermal quality of outdoor space due to installation of vertical greenery. The t mrt of two green walls (Green Wall A and Green Wall B) was measured up to 2 m away at intervals of 0.5 m. Two datasets were obtained, one consisting of t mrt , surface and air Temperature collected from the two green walls and the second for just green wall A and the exposed concrete wall after Green Wall B was removed. t mrt was measured using customised globe thermometers calibrated for local use. Data was analysed using a GIS, thus enabling convenient visual comparison between t mrt profiles at different times. The diurnal t mrt profile was altered significantly due to the installation of vertical greenery. When both green walls were present the peak t mrt occurred at 15:00 h, but with more concrete exposed when one wall was removed, the peak occurred at 17:00 h and was 10.9–12.9° higher at 0.5 m away from the wall. Vertical greenery thus helped to reduce t mrt both during the day and at night, to varying extents. The proposed methodology enables systematic quantification of the effects of vertical greenery on t mrt .
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Effects of vertical greenery on mean Radiant Temperature in the tropical urban environment
Landscape and Urban Planning, 2014Co-Authors: Chun Liang Tan, Nyuk Hien Wong, Steve Kardinal JusufAbstract:Studies on vertical greenery generally focus on the measurement of air Temperature, surface Temperature and cooling load. There is a lack of information on how vertical greenery can influence outdoor thermal comfort. The objective of this study is to quantify the effects of mean Radiant Temperature (tmrt), as the first step towards determining the thermal quality of outdoor space due to installation of vertical greenery.The tmrtof two green walls (Green Wall A and Green Wall B) was measured up to 2m away at intervals of 0.5m. Two datasets were obtained, one consisting of tmrt, surface and air Temperature collected from the two green walls and the second for just green wall A and the exposed concrete wall after Green Wall B was removed. tmrtwas measured using customised globe thermometers calibrated for local use. Data was analysed using a GIS, thus enabling convenient visual comparison between tmrtprofiles at different times. The diurnal tmrtprofile was altered significantly due to the installation of vertical greenery. When both green walls were present the peak tmrtoccurred at 15:00h, but with more concrete exposed when one wall was removed, the peak occurred at 17:00h and was 10.9-12.9° higher at 0.5m away from the wall. Vertical greenery thus helped to reduce tmrtboth during the day and at night, to varying extents. The proposed methodology enables systematic quantification of the effects of vertical greenery on tmrt. © 2014 Elsevier B.V.
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outdoor mean Radiant Temperature estimation in the tropical urban environment
Building and Environment, 2013Co-Authors: Nyuk Hien Wong, Steve Kardinal JusufAbstract:Abstract A large scale estimation of mean Radiant Temperature (tmrt) is conducted at two sites using customised globe thermometers. The measurement points cover a variety of urban typologies such as high-rise offices, parks, large water bodies and housing apartments. Data is derived using a tmrt formula calibrated to the local climate. Measurements for clear, sunny days are used for the analysis of the average diurnal tmrt profile. The diurnal tmrt profile shows that the tmrt differential between points is most evident during daytime, and is affected most significantly by shade cast by trees and buildings. Results also show that common urban constituents such as greenery and large water bodies, while proven to effectively reduce the ambient Temperature of its surroundings throughout the day, do not affect tmrt significantly after nightfall. Further analysis reveals a correlation between sky view factor and tmrt in the day. Measurement points in different parks exhibit contrasting trends in tmrt reduction. Results of the study also provide a realistic threshold for the lowering of outdoor tmrt. Trees, shrubs and green walls may be introduced into the outdoor environment with the intention of reducing tmrt to a desirable level for a specific time range.