Progress in Urban Greenery Mitigation Science – Assessment Methodologies Advanced Technologies and Impact on Cities

Abstract

Urban greenery is a natural solution to cool cities and provide comfort, clean air and significant social, health and economic benefits. This paper aims to present the latest progress on the field of greenery urban mitigation techniques including aspects related to the theoretical and experimental assessment of the greenery cooling potential, the impact on urban vegetation on energy, health and comfort and the acquired knowledge on the best integration of the various types of greenery in the urban frame. Also to present the recent knowledge on the impact of climate change on the cooling performance of urban vegetation and investigate and analyse possible technological solutions to face the impact of high ambient temperatures.

Remote Sensing and Social Sensing Data Reveal Scale-Dependent and System-Specific Strengths of Urban Heat Island Determinants

“…Our findings revealed that vegetation cover generally has the largest strength in shaping the LST patterns at most of the studied scales and lends support to previous argument that the natural surface contributes more to the LST pattern than human activity, and highlight the importance of green vegetation (and nature-based solution) for city planning in the context of climate adaptation [12]. In contrast, some case studies have found that the cooling effect of the water body was better than the green vegetation due to the higher rate of the heat consuming process of transpiration [14,54]. Our results suggest that this is also possible, as for the single-city level, the results of many cities showed that the water body was the dominant factor to explain the LST pattern, especially at finer spatial scales ( Figure 6).…”

“…Within each grid cell, we calculated the natural-surface and non-surface variables. Our natural-surface variables included vegetation cover and water cover (seen in Figure A3, Appendix A) as they are the most commonly used variables in the studies of the surface UHI effect [4,14,19,35]. Within each grid cell, we calculated the mean of the normalized difference vegetation index (NDVI) for all vegetated pixels as an indicator of vegetation cover.…”

“…Typically, the UHI effect can be quantified based on the measurement of near-surface air temperature (referred to as atmospheric UHIs) or land surface temperature (referred to as surface UHIs) [11,12]. Facilitated by readily available remotely sensed data, recent studies have increasingly focused on land surface temperature (LST) as a direct indicator of the surface UHI effect to study how UHIs are shaped by an array of environmental and anthropogenic determinants [13][14][15][16]. It has been well documented that remotely sensed LST is strongly correlated with natural-surface biophysical variables that characterize vegetation and water cover, suggesting that urban vegetation and water bodies have a significant cooling effect [4,14,17,18].…”

“…Facilitated by readily available remotely sensed data, recent studies have increasingly focused on land surface temperature (LST) as a direct indicator of the surface UHI effect to study how UHIs are shaped by an array of environmental and anthropogenic determinants [13][14][15][16]. It has been well documented that remotely sensed LST is strongly correlated with natural-surface biophysical variables that characterize vegetation and water cover, suggesting that urban vegetation and water bodies have a significant cooling effect [4,14,17,18]. A set of remotely sensed indicators of natural-surface properties such as the normalized difference vegetation index (NDVI), the leaf area index (LAI), and the normalized difference water index (NDWI) has therefore been adopted in studies aimed at unraveling the driving factors of UHIs [19,20].…”

An Investigation of the Quantitative Correlation between Urban Morphology Parameters and Outdoor Ventilation Efficiency Indices

“…Atmosphere 2019, 10, 33 14 of 17 with respect to ventilation and human thermo-physiological conditions. Further, the impact of passive methods [58], including vegetation [59][60][61], as well as lift-up design [62], which are becoming increasingly popular in China to improve the pedestrian level wind and thermal comfort.…”