Volume 13, Issue 49 (12-2024)
Haft Hesar J Environ Stud 2024, 13(49): 63-80 |
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Ahmadnejad F, Shahbazi Y, Salimi S. Evaluating the effect of tree shading and street enclosure on the thermal comfort of pedestrians in the UTCI index
(Case study six pedestrian streets in Iran). Haft Hesar J Environ Stud 2024; 13 (49) :63-80
URL: http://hafthesar.iauh.ac.ir/article-1-2141-en.html
URL: http://hafthesar.iauh.ac.ir/article-1-2141-en.html
Abstract: (592 Views)
Introduction: Designing cities with priority for pedestrians is one of the proposed solutions to reduce the problems caused by the use of motorized transportation. Thermal comfort is influential in people's willingness to walk in the environment. This research quantitatively examines the effect of street enclosure and the effect of trees on the thermal comfort of pedestrians on UTCI index.
Methodology: This research has examined 18 sections of 6 " famous pedestrians of Iran", on June 22 from 8:00-20:00. The geometry of the streets, the placement of buildings and trees were modeled based on the existing situation, then they were entered into the Lady Bug plugin connected to Grasshopper in Rhino software. In this research, in addition to examining the effect of changes in the street enclosure and shading of trees on thermal comfort, the influence of two variables of orientation and climatic conditions (air dry temperature, relative humidity, wind speed, radiant temperature) was calculated and by analyzing and comparing different states of thermal comfort in each We have analyzed all the data.
Results: Investigations showed that the orientation of the sidewalk in the hot season of the year is effective on the amount of radiation and air temperature in certain hours of the day, and the east-west sidewalks are hotter in the beginning and end hours of the day, but no significant change is observed in the average daily temperature. The street enclosure has a direct effect on the average daily temperature, in the street enclosure lower than 0٫5 the UTCI temperature is higher than the dry air temperature, and in the street enclosure higher than 0٫5 it is lower than the dry air temperature. Also, in street enclosure higher than 0٫5, the radiation temperature does not exceed the critical value of 60℃, which is the thermal stress limit. The shading effect of trees is dependent on the street enclosure, as the trees in the part of the sidewalk with low enclosure (H/W< 0٫5) reduce the average radiant temperature by 12٫56 ℃ and the emotional temperature by 3٫08 ℃, the greatest reduction in Chaharbagh is Isfahan, where the UTCI temperature decreases by 6٫49 degrees during the day. But in a higher enclosure (H/W>0٫5), the shading of the building affects the shading effect of the trees in such a way that the temperature difference in the presence of trees at higher altitudes is at most one-third of the previous state.
Conclusion: We found that the effect of shading trees on thermal comfort is dependent on the condition of the street enclosure. In streets with a low enclosure ratio, the presence of trees as a canopy has a significant effect on lowering the temperature and better thermal comfort of humans, and this effect decreases with the increase of the enclosure of the street. It should be seen whether the effect of the shadows of the trees is greater or the shadows of the buildings on the street
Methodology: This research has examined 18 sections of 6 " famous pedestrians of Iran", on June 22 from 8:00-20:00. The geometry of the streets, the placement of buildings and trees were modeled based on the existing situation, then they were entered into the Lady Bug plugin connected to Grasshopper in Rhino software. In this research, in addition to examining the effect of changes in the street enclosure and shading of trees on thermal comfort, the influence of two variables of orientation and climatic conditions (air dry temperature, relative humidity, wind speed, radiant temperature) was calculated and by analyzing and comparing different states of thermal comfort in each We have analyzed all the data.
Results: Investigations showed that the orientation of the sidewalk in the hot season of the year is effective on the amount of radiation and air temperature in certain hours of the day, and the east-west sidewalks are hotter in the beginning and end hours of the day, but no significant change is observed in the average daily temperature. The street enclosure has a direct effect on the average daily temperature, in the street enclosure lower than 0٫5 the UTCI temperature is higher than the dry air temperature, and in the street enclosure higher than 0٫5 it is lower than the dry air temperature. Also, in street enclosure higher than 0٫5, the radiation temperature does not exceed the critical value of 60℃, which is the thermal stress limit. The shading effect of trees is dependent on the street enclosure, as the trees in the part of the sidewalk with low enclosure (H/W< 0٫5) reduce the average radiant temperature by 12٫56 ℃ and the emotional temperature by 3٫08 ℃, the greatest reduction in Chaharbagh is Isfahan, where the UTCI temperature decreases by 6٫49 degrees during the day. But in a higher enclosure (H/W>0٫5), the shading of the building affects the shading effect of the trees in such a way that the temperature difference in the presence of trees at higher altitudes is at most one-third of the previous state.
Conclusion: We found that the effect of shading trees on thermal comfort is dependent on the condition of the street enclosure. In streets with a low enclosure ratio, the presence of trees as a canopy has a significant effect on lowering the temperature and better thermal comfort of humans, and this effect decreases with the increase of the enclosure of the street. It should be seen whether the effect of the shadows of the trees is greater or the shadows of the buildings on the street
Keywords: Pedestrian thermal comfort, UTCI, street enclosure, urban geometry, trees, Iran's sidewalks.
Type of Study: Research |
Received: 2023/07/11 | Accepted: 2024/02/2 | Published: 2024/12/30
Received: 2023/07/11 | Accepted: 2024/02/2 | Published: 2024/12/30
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