scholarly journals A Numerical Study on Mitigation Strategies of Urban Heat Islands in a Tropical Megacity: A Case Study in Kaohsiung City, Taiwan

2020 ◽  
Vol 12 (10) ◽  
pp. 3952 ◽  
Author(s):  
Jou-Man Huang ◽  
Liang-Chun Chen
Keyword(s):  
Thermal Environment ◽  
Numerical Study ◽  
Mitigation Strategies ◽  
Comfort Level ◽  
Tropical Region ◽  
Permeable Pavement ◽  
Coverage Ratio ◽  
Urban Heat ◽  
Cooling Effects

In recent years, with the rapid increase in global warming and urbanization, urban heat island effects (UHI) have become an important environmental issue. Taiwan is no exception, with previous studies demonstrating serious UHIs in megacities. Although existing UHI research has utilized computer simulations to analyze improvement scenarios, there are few cooling strategy studies in actual blocks of Taiwan. Therefore, this study selected a block of a megacity in a tropical region of Taiwan as a case study by ENVI-met. Five improvement strategies were tested and compared to the current situation (B0): (1) Case C1 changed to permeable pavement, (2) Case C2 increased the green coverage ratio (GCR) of the street to 60%, (3) Case C3 changed to permeable pavement and increased the GCR in the street to 60%, (4) Case C4 changed to permeable pavement, increased the GCR in the street to 60%, and increased the GCR in the parks to 80%, and (5) Case C5 changed to permeable pavement, increased GCR in the street to 60% and parks to 80%, and set the GCR on the roof of public buildings to 100%. The results showed that the average temperature of the current thermal environment is 36.0 °C, with the comfort level described as very hot. Among the five improvement schemes, C5 had the greatest effect, cooling the area by an average of 2.00 °C. Further analysis of the relationship between the different GCRs of streets (SGCR) and the cooling effects revealed that for every 10% increase in the SGCR, the temperature of the pedestrian layer was reduced by 0.15 °C.

Experimental Study of Non-Sintering Block for Reducing Surface Temperature Using Recycling Bottom Ash

2009 ◽  
Vol 620-622 ◽  
pp. 105-108 ◽  
Author(s):  
Jong Bin Park ◽  
Sang Ho Lee ◽  
Chae Sung Gee ◽  
Hee Bum Pyun
Keyword(s):  
Thermal Environment ◽  
Bottom Ash ◽  
Industrial Applications ◽  
Water Runoff ◽  
Permeable Pavement ◽  
Storm Water Runoff ◽  
Urban Heat ◽  
Pavement Temperature ◽  
Island Phenomena ◽  
By Products

Permeable pavement systems are suitable for a variety of residential, commercial and industrial applications because pavements such as water-retentive or water absorbing pavements are helpful to alleviate urban heat island phenomena by reducing pavement temperature, yet are confined to light duty and infrequent usage. And most of study for the permeable pavement is limited to asphalt pavement. Also, immense quantities of coal combustion by-products are produced every year, but only a small fraction of them are currently utilized, particularly bottom ash which is used in this study. So, in this study, it was intended to develop new permeable and water-absorbing pavement blocks to control pavement temperature and storm water runoff. And mechanical characteristics-compressive strength, porosity etc were carried out. Also, Experiments for thermal environment characteristics and pollution control were carried out in laboratory scale using modified pavement samples. Experimental results indicated that blocks with bottom ash were suited to standard and possessed excellent water-retentive and water purification ability.

Cooling Extent of Green Parks: A Case Study in Beijing

2014 ◽  
Vol 962-965 ◽  
pp. 2005-2017
Author(s):  
Wen Qi Lin ◽  
Xiang Qi Chang ◽  
Na Yan ◽  
Ting Yu
Keyword(s):  
Land Surface ◽  
Urban Heat Islands ◽  
Total Size ◽  
Heat Islands ◽  
Green Areas ◽  
Urban Heat ◽  
Cooling Effects ◽  
Higher Temperature ◽  
Lower Temperature

Cooling effects of green areas are an effective way to mitigate the urban higher temperature caused by urban heat islands. The cooling extent goes beyond a green area’s boundary and extends into its surrounding area. However, measurement of the exact cooling extent and mechanism of such effects had remained unclear. Using Landsat Enhanced Thematic Mapper Plus (ETM+) images of Beijing, we have determined the lower temperature of green cooled areas by land surface temperature, identified green areas’ cooling extents, and evaluated the relation of cooling extents to green areas’ features. Results show that the total size of extended cooled areas is larger than that of total green areas, and the cooling extents and magnitudes are statistically related to the biomass, size and shape of green areas. This study has demonstrated the calculation of cooling extents, and provided an approach to the assessment of cooling effects.

Numerical Simulation on Cooling Effects of Greening for Alleviating Urban Heat Island Effect in North China

2014 ◽  
Vol 675-677 ◽  
pp. 1227-1233 ◽  
Author(s):  
Cheng Chen ◽  
Yu Yue ◽  
Wen Jiang
Keyword(s):  
Numerical Simulation ◽  
Computer Simulation ◽  
Urban Heat Island ◽  
North China ◽  
Thermal Environment ◽  
Heat Island ◽  
Island Effect ◽  
Outdoor Thermal Environment ◽  
Urban Heat ◽  
Cooling Effects

As the climate warming up, the effects of the urban heat island have been an insurmountable issue in the urban development. In this paper, taking Tianjin for example, the research combined computer simulation with on-site measurement to evaluate the effects of different greening ratios on outdoor thermal environment. Besides, the accuracy of the simulation model has been verified by calibration. Research results determined that the increase of the greening ratio in the existing environment could improve the outdoor thermal environment in summer. But the limitations of green cooling was also pointed out, namely that the air temperature would infinitely close to a certain value with further increasing greening ratio.

scholarly journals THE ROLES OF URBAN BUILDINGS AND VEGETATION IN ADJUSTING SEASONAL AND DAILY AIR TEMPERATURE

2019 ◽  
Vol XLII-2/W13 ◽  
pp. 1307-1312
Author(s):  
Y. Lan ◽  
Z. Huang ◽  
R. Guo ◽  
Q. Zhan
Keyword(s):  
Air Temperature ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Thermal Environment ◽  
Mitigation Strategies ◽  
Spatiotemporal Patterns ◽  
Gis Technology ◽  
Night Time ◽  
Urban Buildings ◽  
Urban Heat

<p><strong>Abstract.</strong> Exploring the spatiotemporal patterns of the relationships between urban indicators and urban temperature is essential to improve the mitigation effectiveness when we intend to adjust built environment for moderating urban thermal environment. In this study, RS, GIS technology and statistical methods were involved to investigate the spatiotemporal patterns of the impacts of urban buildings and vegetation on Air Temperature (AT). Building Density (BD) and Normalized Difference Vegetation Index (NDVI) are the indicators for urban buildings and vegetation respectively. The objectives of this study are: 1) to determine an appropriate scale for examining the building-AT relationships and vegetation-AT relationships; 2) to explore the seasonal and daily characteristics of these relationships; and 3) to compare the effects of urban buildings and vegetation. The results show that, for both summer and winter, a scale of 200&amp;ndash;250&amp;thinsp;m is optimal for examining building-AT relationships, and 960&amp;ndash;1020&amp;thinsp;m is the desirable scale for studying vegetation-AT relationships. Based on the optimal scales, we find that for both buildings and vegetation, they only significantly impact night-time temperature in both summer and winter. For seasonal comparison, the building-AT relationships and vegetation-AT relationships are relatively stronger in summer than in winter, which are indicated by R-square of the regression results. When comparing the effects of urban building and vegetation, we find that increasing vegetation is more effective than reduce buildings to achieve the same air temperature reduction. Our findings are conducive to generating space-time targeted Urban Heat Island (UHI) mitigation strategies.</p>

How to assess ecodistrict resilience to urban heat stress under future heatwaves? A case study for the city of Paris

2020 ◽  
pp. 11-24
Author(s):  
Anaïs Machard ◽  
Simon Martinez ◽  
Emmanuel Bozonnet ◽  
Eleonora Lacedra ◽  
Christian Inard
Keyword(s):  
Climate Change ◽  
Heat Stress ◽  
Regional Climate ◽  
Regional Climate Change ◽  
Mitigation Strategies ◽  
Anthropogenic Sources ◽  
New Paradigm ◽  
Mitigation And Adaptation ◽  
Urban Heat

It is now well-known that the frequency, intensity and duration of heatwaves will strongly increase along the XXIth century, which introduces the urban built environment resilience as a new paradigm. In Paris, the intense 2003 heatwave demonstrated that warm urban temperatures could result in serious adverse health issues. Temperatures were particularly elevated during nighttime, due to the urban heat island effect. Since air-conditioning has not penetrated yet in residential French buildings, studying the potential of combined mitigation strategies at the district and building scale to increase the neighbourhood and buildings resilience in strong urbanized areas under future heatwaves is a key subject matter. The climate change aspect is integrated through a future heatwave weather file, re-assembled from dynamically downscaled multi-year regional climate change projections from the EURO-CORDEX project. The new ecodistrict Clichy-Batignolles in central Paris is chosen as a case study, recognized as innovative for low-energy and environmental solutions. It is composed of high-rise residential and commercial buildings, large green areas, cool surfaces, and reduced anthropogenic sources. We used an Urban Canyon Model (Urban Weather Generator) to model the neighbourhood and different design configurations (building height and density, green and cool surfaces). The designs and measures were evaluated through a sensitivity analysis to analyse their potential to mitigate the urban local microclimate air temperature during the heatwaves. We quantified the neighbourhood resilience and found that the ecodistrict is exposed to a strong urban heat stress under the future intense heatwave. These results highlight how outdoor overheating assessment can be used to evaluate the district mitigation and adaptation strategies. This approach can be used for urban planning, while the modelled future urban heatwaves can be used as an input for building simulations and evaluate the resilience of the buildings to urban heat stress.

scholarly journals The Potential of Stormwater Management in Addressing the Urban Heat Island Effect: An Economic Valuation

2021 ◽  
Vol 13 (16) ◽  
pp. 8685
Author(s):  
Daniel Johnson ◽  
Judith Exl ◽  
Sylvie Geisendorf
Keyword(s):  
Urban Heat Island ◽  
Green Infrastructure ◽  
Stormwater Management ◽  
Economic Feasibility ◽  
Mitigation Strategies ◽  
Social Value ◽  
Cost Ratio ◽  
Heat Island ◽  
Urban Heat ◽  
Cooling Effects

Urban green infrastructure (UGI) within sustainable stormwater management provides numerous benefits to urban residents, including urban heat island (UHI) mitigation. Cost–benefit analyses (CBA) for UGI have been conducted at neighborhood level with a focus on stormwater management, but valuations of reductions in heat-related hospitalizations and mortality are lacking. These benefits create significant social value; the quantification thereof is essential for urban planning in providing a scientific foundation for the inclusion of UGI in UHI mitigation strategies. This study assesses the potential of three UGI scenarios developed for an urban neighborhood in Berlin, Germany. First, climate data analyses were conducted to determine the cooling effects of tree drains, facade greening, and green roofs. Second, a CBA was performed for each scenario to value UHI mitigation by estimating the damage costs avoided in reduced heat-related hospitalizations and fatalities, using the net present value (NPV) and benefit–cost ratio (BCR) as indicators of economic feasibility. The results indicate heat mitigation capabilities of all three UGI types, with tree drains achieving the strongest cooling effects. Regarding economic feasibility, all scenarios achieve positive NPVs and BCRs above one. The findings confirm the potential of stormwater management in mitigating UHI and generating substantial social value.

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