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Highlights • Investigated heat mitigation strategies at neighborhood scale. • Quantified changes to surface energy balance from heat mitigation. • Additional trees and cool pavements led to largest reductions in air temperature. • Also investigated the effects of spatial scale of heat mitigation adoption. Abstract Heat mitigation strategies can reduce excess heat in urban environments. These strategies, including solar reflective cool roofs and pavements, green vegetative roofs, and street vegetation, alter the surface energy balance to reduce absorption of sunlight at the surface and subsequent transfer to the urban atmosphere. The impacts of heat mitigation strategies on meteorology have been investigated in past work at the mesoscale and global scale. For the first time, we focus on the effect of heat mitigation strategies on the surface energy balance at the neighborhood scale. The neighborhood under investigation is El Monte, located in the eastern Los Angeles basin in Southern California. Using a computational fluid dynamics model to simulate micrometeorology at high spatial resolution, we compare the surface energy balance of the neighborhood assuming current land cover to that with neighborhood-wide deployment of green roof, cool roof, additional trees, and cool pavement as the four heat mitigation strategies. Of the four strategies, adoption of cool pavements led to the largest reductions in net radiation (downward positive) due to the direct impact of increasing pavement albedo on ground level solar absorption. Comparing the effect of each heat mitigation strategy shows that adoption of additional trees and cool pavements led to the largest spatial-maximum air temperature reductions at 14:00 h (1.0 and 2.0 °C, respectively). We also investigate how varying the spatial coverage area of heat mitigation strategies affects the neighborhood-scale impacts on meteorology. Air temperature reductions appear linearly related to the spatial extent of heat mitigation strategy adoption at the spatial scales and baseline meteorology investigated here. [ABSTRACT FROM AUTHOR]

Due to the ongoing global warming, heat mitigation strategies are becoming implemented through practice and simulations. These efforts aim to make the cities that are dealing with the urban heat island more livable. The effect of heat mitigation strategies on climate condition and energy consumption have been studied and compared, previously. In this paper, the effect of these strategies on human thermal comfort in urban open spaces is reviewed. Specifically, the review is focused on vegetation (in the form of parks, street trees, green roofs and green walls), and highly reflective materials (on roof and on the ground level) as the most common strategies for improving the thermal conditions in cities. Several studies done by simulation or through field measurement in different countries are described. The most important finding of the review is the fact that although highly reflective materials reduce air temperature in urban open spaces, they increase the re-radiation of sun to the pedestrians. Therefore, vegetation is a better choice for improving thermal comfort in the pedestrian level. [ABSTRACT FROM AUTHOR]

Natural elements such as vegetation and water bodies may help reduce heat in urban spaces in summer or in hot climates. This effect, however, has rarely been studied during cold seasons. This paper briefly studies the effect of vegetation and water in summer and more comprehensively in winter. Both studies are done in courtyards on two university campuses in temperate climates. A scale model experiment with similar materials supports the previous studies. The summer study is done in Portland (OR), USA, and the winter study (along with the scale model) in Delft, the Netherlands. The summer study shows that a green courtyard at most has a 4.7 °C lower air temperature in the afternoon in comparison with a bare one. The winter study indicates that the air temperature above a green roof is higher than above a white gravel roof. It also shows that, although a ‘black’ courtyard has higher air temperatures for a few hours on sunny winter days, a courtyard with a water pond and with high amounts of thermal mass on the ground has a warmer and more constant air temperature in general. Both the summer and winter studies show that parks in cities have a lower and more constant air temperature compared to suburbs, both in summer and winter. The scale model also demonstrates that although grass has a lower albedo than the used gravel, it can provide a cooler environment in comparison with gravels and black roof. 1 [ABSTRACT FROM AUTHOR]

The increased frequency of heat-related mortality and morbidity in urban environments indicates the importance of urban climate studies. As most of the world's population lives in cities, the education of designers, planners and policy makers is crucial to promote urban sustainability This paper, firstly, focuses on the different factors causing the urban heat islands in large cities. Secondly, it considers how these factors are reflected in higher education programmes. Examples are shown from courses in UK higher education, explaining the common software tools used for simulating urban spaces, and student field measurements are drawn on to illustrate how urban climate studies are included in higher education curricula. Urban metabolism is used to conceptualise the main approach to systemic resource-use assessments and as a holistic framework to investigate the main drivers of the urban heat island phenomenon. To sum up, this paper reflects on the importance of training climatically-aware graduates from design schools. [ABSTRACT FROM AUTHOR]

The aim of this study was to understand the effect of urban street greenery type and arrangements on thermal comfort and heat stress in summer. Field measurements and computer simulations were carried out on East-West (E-W) and North-South (N-S) oriented streets in Isfahan, Iran. Through the field measurements in July 2014, 17 different streets were studied, followed by 15 perturbation scenarios (urban design alternatives) simulated by ENVI-met. The study showed that there is a significant and positive relationship between the Sky View Factor (SVF) and the Physiological Equivalent Temperature (PET) values. Comparison of the meteorological parameters within different street orientations showed that the effect of the SVF on the E-W streets was more significant than in N-S streets. Furthermore, greenery arrangement and building heights showed different impacts on the outdoor thermal comfort streets with different orientations. • The effect of different street greenery arrangements on thermal comfort was studied. • A significant positive relationship between SVF and PET was observed. • SVF of more than 0.6 leads to higher heat stress. • The effect of the SVF on the microclimate of E-W streets was more N-S. [ABSTRACT FROM AUTHOR]