Intra-Urban Air Temperature Distribution, Urban Heat Island and Thermal Comfort Implications in A Subtropical City

2016 ◽  
Vol 2 (2) ◽  
pp. 127-137
Author(s):  
E. Krüger ◽  
◽  
E. Dumke ◽  
F. Mendonça
Keyword(s):  
Temperature Distribution ◽  
Thermal Comfort ◽  
Urban Heat Island ◽  
Air Temperature ◽  
Urban Air ◽  
Heat Island ◽  
Urban Heat

scholarly journals Green Envelop Impact on Reducing Air Temperature and Enhancing Outdoor Thermal Comfort in Arid Climates

2019 ◽  
Vol 5 (5) ◽  
pp. 1124-1135 ◽  
Author(s):  
Sherine Wahba ◽  
Basil Kamil ◽  
Khaled Nassar ◽  
Ahmed Abdelsalam
Keyword(s):  
Thermal Comfort ◽  
Urban Heat Island ◽  
Air Temperature ◽  
Electricity Consumption ◽  
Green Roofs ◽  
Mean Value ◽  
Outdoor Thermal Comfort ◽  
Heat Island ◽  
Consumption Rates ◽  
Urban Heat

Today Urban Cities faces energy and environmental challenges due to increased population, higher urbanization. The building sector has a big responsibility as it acquires high consumption rates in global energy and environmental scenarios. It is thought that the built environment in Egypt is responsible for 26% of the total overall national energy consumption, 62% of the total electricity consumption and around 70% of resultant CO2 emissions. The increased use of electrical appliances causes Urban Heat Island effect (UHI), which affect major urban centres. Adding green elements to any urban area is proved to be an effective strategy with numerous benefits to enhance the city's ecosystem, also mitigate the urban heat island measures. In this research Green roofs/walls can regulate outdoor air temperature by 10°C and improve outdoor thermal comfort by 2 Predicted Mean Value (PMV) values. The modelling of green strategy models can take into consideration design developments in areas with hot and dry climatic zones. The properties of green walls can directly affect the results of thermal comfort as leafs absorbs, reflects and transmits solar radiation, and increases the evapotranspiration.

Temperature adjustments for design data for urban air conditioning design

2017 ◽  
Vol 39 (2) ◽  
pp. 211-218 ◽  
Author(s):  
Geoffrey Levermore ◽  
Stefan Vandaele ◽  
John Parkinson
Keyword(s):  
Urban Heat Island ◽  
Air Temperature ◽  
Air Conditioning ◽  
Solar Irradiation ◽  
Urban Heat Island Intensity ◽  
Wave Radiation ◽  
Urban Air ◽  
Heat Island ◽  
Urban Heat ◽  
Radiant Temperature

The urban heat island, where the urban area air temperature is higher than the nearby rural or semi-rural air temperature reference site, is now hopefully well known. The urban heat island intensity is the actual urban air temperature minus the rural air temperature. However, the “air conditioned urban heat island intensity” is measured by the air temperature sensor in an air conditioning condenser unit minus the rural air temperature. This is often different to the standard urban heat island intensity. Designers need to appreciate this difference, as it determines how the air conditioning system performs. It is most likely affected by the radiant temperature. This can also vary significantly from the rural, semi-rural radiant temperature due to the variation in solar absorptance of the urban buildings and the shading effects. Measurements have shown significant variations in the infrared temperatures over the urban areas. Calculations of the radiant absorption and long wave radiation loss also show significant differences to the rural counterparts in frequency and magnitude. This “surface urban heat island” is important for air conditioning plant situated often in areas exposed to solar irradiation. The exhaust air from the air conditioning units itself is also briefly considered. This paper examines these effects and proposes how the engineer can include for them in design. Practical application:The results of this paper will be useful for designers of buildings with air conditioning and air conditioning plant itself to assess the effect of the micro urban heat island. This micro urban heat island surrounds the air conditioning plant. The example is for London.

OVERVIEW OF URBAN HEAT ISLAND (UHI) PHENOMENON TOWARDS HUMAN THERMAL COMFORT

2017 ◽  
Vol 16 (9) ◽  
pp. 2097-2111 ◽  
Author(s):  
Mohanadoss Ponraj ◽  
Yee Yong Lee ◽  
Mohd Fadhil Md Din ◽  
Zainura Zainon Noor ◽  
Kenzo Iwao ◽  
...  
Keyword(s):  
Thermal Comfort ◽  
Urban Heat Island ◽  
Heat Island ◽  
Human Thermal Comfort ◽  
Urban Heat

scholarly journals Biomimicry-Based Strategies for Urban Heat Island Mitigation: A Numerical Case Study under Tropical Climate

Biomimetics ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 48
Author(s):  
Kevin Araque ◽  
Paola Palacios ◽  
Dafni Mora ◽  
Miguel Chen Austin
Keyword(s):  
Thermal Comfort ◽  
Urban Heat Island ◽  
Urban Areas ◽  
Outdoor Thermal Comfort ◽  
Base Case ◽  
Heat Island ◽  
Urban Heat ◽  
Historical Heritage ◽  
Pet Index ◽  
Radiant Temperature

In recent years, demographic growth has caused cities to expand their urban areas, increasing the risk of overheating, creating insurmountable microclimatic conditions within the urban area, which is why studies have been carried out on the urban heat island effect (UHI) and its mitigation. Therefore, this research aims to evaluate the cooling potential in the application of strategies based on biomimicry for the microclimate in a historical heritage city of Panama. For this, three case studies (base case, case 1, and case 2) of outdoor thermal comfort were evaluated, in which the Envi-met software was used to emulate and evaluate the thermal performance of these strategies during March (highest temperature month) and October (rainier month). The strategies used were extracted from the contrast of zebra skin, human skin, evaporative cooling, and ant skin. The results showed a reduction of 2.8 °C in the air temperature at 11:00, the radiant temperature decreased by 2.2 °C, and the PET index managed to reduce the thermal comfort indicator among its categories. The importance of thinking based on biomimicry in sustainable strategies is concluded; although significant changes were obtained, high risks of discomfort persist due to the layout and proximity of the building.

scholarly journals A High-Resolution Monitoring Approach of Canopy Urban Heat Island using Random Forest Model and Multi-platform Observations

2021 ◽  
Author(s):  
Shihan Chen ◽  
Yuanjian Yang ◽  
Fei Deng ◽  
Yanhao Zhang ◽  
Duanyang Liu ◽  
...  
Keyword(s):  
High Resolution ◽  
Random Forest ◽  
Urban Heat Island ◽  
Air Temperature ◽  
Anthropogenic Heat ◽  
Heat Island ◽  
Model Framework ◽  
Rapid Urbanization ◽  
Urban Heat ◽  
The City

Abstract. Due to rapid urbanization and intense human activities, the urban heat island (UHI) effect has become a more concerning climatic and environmental issue. A high spatial resolution canopy UHI monitoring method would help better understand the urban thermal environment. Taking the city of Nanjing in China as an example, we propose a method for evaluating canopy UHI intensity (CUHII) at high resolution by using remote sensing data and machine learning with a Random Forest (RF) model. Firstly, the observed environmental parameters [e.g., surface albedo, land use/land cover, impervious surface, and anthropogenic heat flux (AHF)] around densely distributed meteorological stations were extracted from satellite images. These parameters were used as independent variables to construct an RF model for predicting air temperature. The correlation coefficient between the predicted and observed air temperature in the test set was 0.73, and the average root-mean-square error was 0.72 °C. Then, the spatial distribution of CUHII was evaluated at 30-m resolution based on the output of the RF model. We found that wind speed was negatively correlated with CUHII, and wind direction was strongly correlated with the CUHII offset direction. The CUHII reduced with the distance to the city center, due to the de-creasing proportion of built-up areas and reduced AHF in the same direction. The RF model framework developed for real-time monitoring and assessment of high-resolution CUHII provides scientific support for studying the changes and causes of CUHII, as well as the spatial pattern of urban thermal environments.

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