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Comparing the effects of Urban Heat Island Mitigation Strategies for Toronto, Canada
... These results are imperative for understanding urban heat formation in different climates and cities [144,145]. In Period-3, the most cited papers of S31, S32, and S33 were casebased empirical studies with numerous scenarios for comprehensively understanding urban heat drivers and mitigation strategies [146][147][148]. Both S34 and S35 are review papers for understanding the adoption of CFD techniques for microclimate simulation and estimation and the progress of urban heat mitigation strategies [149,150]. ...
... ''Thermal comfort" is the largest node, having the strongest connection with ''microclimate", ''heatisland mitigation", ''mean radiant temperature, and "design" within the RC-2 cluster and air-temperature in RC-1 cluster. On the one hand, this suggests ''thermal comfort" was one of the key indicators of microclimatic studies and a fundamental performance measure of ''heat-island mitigation" [41,85,146,173]. However, both ''air temperature" and ''mean radiant temperature" are the two most important factors for thermal comfort regulation [111,125,138,148]. ...
... The term co-occurrence analysis also suggests that the ''PET" (Physiological Equivalent Temperature) has been an important assessment indicator of thermal comfort and urban microclimate [23,104,148]. Both numerical simulations and ''numerical simulation" and ''ENVI-met software" were found to be the key methods and tools for microclimate studies [25,146,148,149,176]. An increase in temperature can cause photochemical effects, leading to an increase in ozone concentration. ...
This paper presents a bibliometric review of the history and evolution of Urban Heat Mitigation and Adaptation (UHMA) from 1989 to 2021 to identify research progress, knowledge gaps, and future research directions. The results indicate that research on UHMA is booming and that the field has diversified over time. Existing studies have examined UHMA from the environmental, technical, health, economic, and social perspectives. Over time, UHMA has evolved into a transdisciplinary research field, covering many emerging areas beyond built environments, including materials, computer sciences, physiology, chemistry, and geosciences. Relevant UHMA topics can be divided into four research clusters: (i) UHI impact assessment and cause identification, (ii) microclimate regulation and human thermal comfort, (iii) climate-related health impact and adaptation, and (iv) urban heat mitigation strategies and techniques. This study highlights some knowledge gaps in UHMA research, including (i) overfocusing on urban heat causes, effects, and mitigation solutions; (ii) more focus on mitigation, overshadowing adaptation, and preparation; (iii) highlighting materials and vegetation, but overlooking water features and urban form; (iv) incomplete understanding of heat-related impacts; (v) focusing more on microclimate and heat islands rather than extreme heat; (vi) unsound policy, social, and economic support; and (vii) lack of actual UHMA implementation. There are also some challenges in UHMA development, including (i) the uneven distribution of publications, authors, and affiliations; (ii) topic, affiliation, and nation aggregation and bias; (iii) slow evolution in key disciplines, publications, and authors; (iv) knowledge isolation owing to tendentious academic collaboration and communication; and (v) limited journal scope and restricted methodological approaches. To overcome such challenges and enhance UHMA research and policy, 13 suggestions were made. Overall, by promoting trans-disciplinary UHMA research informed by climatic sciences, scientific models, policy-relevant techniques, and socio-economic support, this study is expected to better frame UHMA research and bridge science and policy.
... These two indicators reflect the thermal comfort of the space from different perspectives. In recent years, many papers have used these parameters as evaluation indicators to study the thermal environment [37]. ...
... This, in turn, blocked the interior space of the residential district, which resulted in lower AT during the day. This result was consistent with the findings of Wang et al. on the urban scale [37]. The cooling from day to night was similar, and the AT at night was also the lowest in high-plot-ratio districts. ...
... Conversely, tree planting also blocks wind circulation and reduces WS, which can be detrimental to the diffusion of hot air, thus leading to higher nighttime temperatures. This is at odds with the findings of Wang et al. [37]. The main reason for this difference in result may be that the form and layout of buildings in residential districts and in the city may be vastly different, which could have a significant impact on the wind. ...
Residential districts account for the most common type of urban land coverage. Massive developments with high density have a huge impact on the urban climate. In this study, we explored the thermal environment optimization strategies of residential districts with different development intensities (plot ratios) from the perspective of urban renewal and residential district design in Xi’an, China. We selected residential districts with low, medium, and high plot ratios in Xi’an City for field measurements and environmental simulation according to five proposed optimization strategies. By comparing the air temperature, mean radiant temperature, and physiological equivalent temperature at the pedestrian height, 1.5 m from the ground, we explored the thermal environment optimization texture of each strategy. The results showed that the same strategy introduced different effects in different residential districts. Increasing the road reflectivity had the best effect on residential districts that had a low plot ratio, whereas planting trees was the best effect in districts with medium and high plot ratios. Planting lawns had a better effect in districts with high plot ratios. The findings of this study provide suggestions for the optimization and reconstruction of residential districts and contribute to future residential district development and design.
... The heat reflected by high-density structures in urban areas increases UHI by reducing wind speed and changing cloud cover [17][18][19][20]. A space with high-rise buildings exhibits lower surface temperatures than a space with mediumor low-rise buildings because urban canopies create large shadow areas, reducing solar radiation during daytime [21,22]. In addition, the configuration of buildings can increase the reflection of solar radiation or decrease the amount of air circulating around buildings, thereby raising the temperature [23]. ...
... Wang et al. [22] A 10% increase in vegetation cover in urban areas lowers mean air temperature by 0.5-0.8 • C. Toronto ...
... Even in a hot and arid climate, an increase in solar reflection due to cool pavement in urban areas can increase the heat stress of pedestrians [137,138]. It is cost-efficient to use cool materials; however, overall, it is more effective to rely on vegetation cover, green space, and trees to mitigate UHI effect [22,122,128]. The most effective means of lowering UHI intensity is reducing building density and paved surface area while simultaneously increasing green space and surface water in high-density areas [111,128]. ...
With the global acceleration of urbanization, temperatures in cities are rising continuously with global climate change, creating an imminent risk of urban heat islands and urban heating. Although much research has attempted to analyze urban heating from various perspectives, a comprehensive approach to urban planning that addresses the problem is just beginning. This study suggests a conceptual framework for multidisciplinary understanding of urban heating by reviewing 147 selected articles from various fields, published between 2007 and 2021, that discuss urban heating mitigation. From these, we identified several outdoor and indoor temperature-reduction factors and proposed area-based, zoning-based, and point-based approaches to mitigate urban heating.
... Residential areas can be designed with larger SVF's to allow for cooling at night, but warmer temperatures during the day, while areas with high daytime occupancy may wish to lower SVF's to create urban canyons and lower street level temperatures during the day but allow warmer temperatures at night. Height-to-width ratios of 0.5 with a building density of around 0.3 are being suggested as a geometry ratio to reduce UHI effects [17]. When considering which UHI mitigation solution to analyse in each urban form, the following characteristics, as presented in Table 2, should be considered. ...
... By switching from asphalt to concrete in both residential and high-rise areas a ground surface temperature reduction up to 7.9 • C at 12:00 pm may be possible in Toronto, Canada [17]. A drawback to using reflective materials on urban surfaces is that if not accounted for, the reflected radiation can become trapped by the urban form or unintentionally reflected onto adjacent buildings or pedestrians. ...
... A drawback to using reflective materials on urban surfaces is that if not accounted for, the reflected radiation can become trapped by the urban form or unintentionally reflected onto adjacent buildings or pedestrians. The reflected energy can affect the overall energy balance of buildings and pedestrians, leading to periods where overheating and or thermal discomfort can occur [17]. In order to reduce the diffuse scattering of radiation reflected from high-albedo surfaces, the use of retro-reflective materials was proposed [37]. ...
Canada is warming at double the rate of the global average caused in part to a fast-growing population and large land transformations, where urban surfaces contribute significantly to the urban heat island (UHI) phenomenon. The federal government released the strengthened climate plan in 2020, which emphasizes using nature-based solutions (NBSs) to combat the effects of UHI phenomenon. Here, the effects of two NBSs techniques are reviewed and analysed: increasing surface greenery/vegetation (ISG) and increasing surface reflectivity (ISR). Policymakers have the challenge of selecting appropriate NBSs to meet a wide range of objectives within the urban environment and Canadian-specific knowledge of how NBSs can perform at various scales is lacking. As such, this state-of-the-art review intends to provide a snapshot of the current understanding of the benefits and risks associated with the implantation of NBSs in urban spaces as well as a review of the current techniques used to model, and evaluate the potential effectiveness of UHI under evolving climate conditions. Thus, if NBSs are to be adopted to mitigate UHI effects and extreme summertime temperatures in Canadian municipalities, an integrated, comprehensive analysis of their contributions is needed. As such, developing methods to quantify and evaluate NBSs’ performance and tools for the effective implementation of NBSs are required.
... Dentre as diversas propostas de modelo de ocupação, o modelo de cidade compacta surge como conceito para o planejamento de cidades sustentáveis (GIVONI, 1998;HIGUERAS, 2006;DUARTE, 2012;TORRES;BAR-BOSA, 2015;SILVA JÚNIOR, 2016;BERARDI;AKBARI, 2016;. De acordo com Barbirato, Torres e Barbosa (2015), o modelo de malha urbana dispersa gera problemas ambientais em face ao espalhamento da estrutura urbana, eliminando coberturas vegetais nativas, aumentando demandas por consumo de energia, exigindo intenso uso de veículos para transporte de mercadorias e pessoas (que, consequentemente, aumenta a poluição do ar por meio da emissão de gases provenientes de combustíveis fósseis), afetando, também, a elevação da impermeabilização do solo natural decorrente da pavimentação excessiva (exercendo sérios danos ao ciclo hidrológico, causando enchentes, impactando o clima urbano). ...
... Dentre as diversas propostas de modelo de ocupação, o modelo de cidade compacta surge como conceito para o planejamento de cidades sustentáveis (GIVONI, 1998;HIGUERAS, 2006;DUARTE, 2012;TORRES;BAR-BOSA, 2015;SILVA JÚNIOR, 2016;BERARDI;AKBARI, 2016;. De acordo com Barbirato, Torres e Barbosa (2015), o modelo de malha urbana dispersa gera problemas ambientais em face ao espalhamento da estrutura urbana, eliminando coberturas vegetais nativas, aumentando demandas por consumo de energia, exigindo intenso uso de veículos para transporte de mercadorias e pessoas (que, consequentemente, aumenta a poluição do ar por meio da emissão de gases provenientes de combustíveis fósseis), afetando, também, a elevação da impermeabilização do solo natural decorrente da pavimentação excessiva (exercendo sérios danos ao ciclo hidrológico, causando enchentes, impactando o clima urbano). ...
... Os principais benefícios dos revestimentos com baixa absortância solar, quando aplicados no envelope dos edifícios e em pavimentos urbanos, consistem basicamente na melhoria das condições de conforto térmico interno e externo no verão, com contribuições em diversas escalas: microclimáticas (internas e externas) e na escala mesoclimática, em conjunto com o clima global (COTANA et al., 2014;ROSSI et al., 2013;DAMON;SETO, 2012). Ao mesmo tempo, se revestimentos de baixa absortância solar são também aplicados sobre coberturas e paredes de edificações, podem reduzir a necessidade de energia e as emissões de CO2eq para refrigeração necessária à operação dos sistemas artificiais de climatização (HVAC), ou ainda, como técnica de resfriamento passivo podem melhorar as condições de conforto térmico no interior das edificações (PISELLO et al., 2016;WANG;BERARDI;AKBARI, 2016). ...
... Os principais benefícios dos revestimentos com baixa absortância solar, quando aplicados no envelope dos edifícios e em pavimentos urbanos, consistem basicamente na melhoria das condições de conforto térmico interno e externo no verão, com contribuições em diversas escalas: microclimáticas (internas e externas) e na escala mesoclimática, em conjunto com o clima global (COTANA et al., 2014;ROSSI et al., 2013;DAMON;SETO, 2012). Ao mesmo tempo, se revestimentos de baixa absortância solar são também aplicados sobre coberturas e paredes de edificações, podem reduzir a necessidade de energia e as emissões de CO2eq para refrigeração necessária à operação dos sistemas artificiais de climatização (HVAC), ou ainda, como técnica de resfriamento passivo podem melhorar as condições de conforto térmico no interior das edificações (PISELLO et al., 2016;WANG;BERARDI;AKBARI, 2016). ...
A incidência de radiação solar nos edifícios é considerada uma das principais responsáveis pela sua carga térmica e seu impacto dependerá, entre outros fatores, da absortância solar das superfícies externas da edificação. Este trabalho analisa o conforto térmico dos usuários de uma habitação unifamiliar térrea, pela metodologia da ASHRAE 55/2013, no contexto de três cidades classificadas em diferentes zonas bioclimáticas: Curitiba (ZB1), Maringá (ZB3) e Belém (ZB8). O método é composto das seguintes etapas: 1. Seleção da tipologia e cidades representativas; 2. Seleção dos valores de absortância; 3. Simulações através do software EnergyPlus e 4. Análise dos resultados. Os resultados demonstraram que a absortância das envoltórias apresentou influência significativa no conforto térmico dos usuários e no aumento da carga térmica interna. As telhas e as tintas, com valores de absortância mais elevados, foram responsáveis, respectivamente, pelo acréscimo de até 24,74% e 17,55% no total de horas anuais em desconforto por calor. No inverno, telhas e tintas com maior absortância apresentaram influência no decréscimo de até 17,07% e 13,7% no total de horas anuais em desconforto por frio. Conforme esperado, é recomendada a utilização de absortâncias mais baixas e altas para zonas bioclimáticas mais quentes e mais frias, respectivamente. Em relação a regiões em que tanto o desconforto por calor quanto por frio é significativo, recomenda-se a escolha criteriosa da absortância, considerando fatores como diferentes sistemas construtivos, uso de ventilação natural e de dispositivos de sombreamento, entre outras soluções, visando a melhoria do conforto térmico dos usuários.
... Urban Heat Island studies are important to urban climatologists, urban planners and the health sectors and more important for the comfort of urban residents and can be studied by means of Land Surface Temperature (LST) and air temperature difference between urban and rural areas (Wang et al., 2015b). Previous studies have demonstrated that the LST product retrieved from thermal infrared (TIR) sensors can be used to monitor the UHI effect (Lin et al., 2005;Weng & Fu, 2014). ...
... A number of satellite methods are available that can be used to examine the LST and determine the UHI effects. Landsat Bands are the data that are most widely used for these studies (Jiménez-Muñozoz et al., 2014;Jin et al., 2015;Sekertekin et al., 2016;Wang et al., 2015b;Yu et al., 2014). Several studies (Wang et al., 2015a;Allegrini et al., 2015;Tyubee & Anyadike, 2015;Usman, 2013;Qin et al., 2001;Awuh et al., 2018;Awuh et al., 2019) have estimated air temperatures using Landsat TM Imageries. ...
... According to Wang et al., 2015, most of Canada, particularly in the Toronto area and parts of British Columbia, will likely experience more frequent heatwaves every summer with temperatures of 30 • C or higher. Along with the rise in average temperatures, the relative mortality is expected to increase by 4-7% for each increase of 2-3 • C in the urban area (5). ...
... Extreme heat can catalyze chemical reactions by transforming car emissions and other air pollutants into ground-level ozone and smog, affecting outdoor air quality (1,5). Extreme heat also impacts wildfire occurrences due to having longer fire seasons, more dry trees to burn, and more frequent storms and lightning to start the fires (1). ...
Extreme Heat Events (EHEs) are increasing in frequency, intensity, and duration in Canada that are resulting in high numbers of preventable heat-related illnesses and deaths. Apart from heat related injuries, extreme heat can catalyze reactions to worsen the outdoor air quality, increase wildfire occurrences, and worsen pre-existing heart conditions or chronic illnesses. Assessing the general public’s knowledge of protective measures against EHEs is needed to prevent further heat-related injuries. In addition, the general public’s knowledge of climate change can be determined to assess if they are aware of the contribution of extreme heat.
... Changes in land use and land cover caused by anthropic action contribute to the increase in surface temperature. In addition, the accelerated growth of urban centers stands out as the main contributing agent in the modification of natural surfaces (Bose and Chowdhury 2020) and, consequently, changes in the thermal sensation on the planet, motivating studies aimed at understanding and mitigating its impacts (Wang et al. 2016;Silva et al. 2018;Sannigrahi et al. 2018;Libanda et al. 2020). ...
The present work was carried out in the city of Recife, Pernambuco State, Brazil, one of the largest coastal cities in Northeast Brazil (NEB). The thermal behavior of a roof slab was verified before and after the installation of a green roof through thermal images, as well as the characterization of the spatial variability of the temperature of its internal surface applying geostatistical interpolation models, with emphasis on the characterization of the environmental thermal comfort. From the temperature matrices extracted from the captured thermal images, statistical and geostatistical analysis was performed. The Human Comfort Index (HCI) was calculated for the indoor environment. The results demonstrate that the adoption of the green roof significantly reduced the slab inner surface temperature, provided by the vegetation presence. The model that best characterized the effects of the green roof presence on the slab was the exponential, with a strong degree of spatial dependence (DSD < 25%) and significant fit (R2 > 0.99). The characterization of the thermal variability of the indoor environment allowed identifying an average reduction in the HCI of 5.88 °C after the green roof installation, keeping it within the comfort zone in the range of 22.68 to 24.46 °C. Infrared thermography associated with geostatistical techniques proved to be effective in mapping and characterizing the slab temperature under green roof coverage, contributing to sustainable urban planning and the formulation of public policies to mitigate the effects of urban heat islands.
... Mountains are one of the most vital ecosystems for the world population because they offer clean water and energy that supports biodiversity [4,5]. The mountain elevation provides for cooler climates and its rugged terrain discourages human intrusion [6]. These characteristics promote the existence of species that are endemic to the area [7]. ...
Advancement in remote sensing platforms, sensors, and technology has significantly improved the assessment of hard-to-access areas, such as mountains. Despite these improvements, Africa lags in terms of research work published. This is of great concern as the continent needs more research to achieve sustainable development. Therefore, this study applied a bibliometric analysis of the annual production of publications on the application of remote sensing methods in mountainous environments. In total, 3849 original articles between 1973 and 2021 were used, and the results indicate a steady growth in publications from 2004 (n = 26) to 2021 (n = 504). Considering the source journals, Remote Sensing was the top-ranked, with 453 total publications. The University of the Chinese Academy of Sciences was the highest-ranking affiliation, with 217 articles, and China produced the highest number of publications (n = 217). Keywords used between 1973 and 1997, such as “Canada”, “alps”, and “GIS”, metamorphosed into “remote sensing” between 1998 and 2021. This metamorphosis indicates a change in the areas of interest and an increase in the application of remote sensing methods. Most studies were conducted in the Global North countries, and a few were published in low-impact journals within the African continent. This study can help researchers and scholars better understand the progress and intellectual structure of the field and future research directions in the application of remote sensing methods in mountainous environments.
... They have depicted that high albedo facades could considerably decrease the cooling load of the buildings, whereas they increase the heating energy demand of the buildings (Cheng et al. 2005). On the other hand, colors with a high absorptance ratio could contribute to the heating load of the buildings and simultaneously increase the requested energy for cooling (Wang et al. 2016). ...
Buildings consume about 40% of global energy. It is essential to use various measures to reduce the energy consumption of the buildings as much as possible. This research investigates the impact of using a new combination of thermochromic (TC) materials in the building envelope of educational buildings. A case study building at Razi University was selected, and a 3D model was created in DesignBuilder software. Firstly, TC coating for external walls was entered into the base model, and several simulations were performed to find the effect of this coating on the energy consumption of the building. Then, a low-emissivity thermochromic (LETC) window was defined using energy management system (EMS) scripting and was entered into the base model. Finally, these two measures were combined, and the cumulative effect of using both TC coating on the external walls and LETC window was identified. Results indicated that the simultaneous application of these two measures reduced the heating demand of the building more in Tabriz, with the least cooling degree days (CDD). Also, simulation results revealed that the simultaneous use of these measures decreased the cooling demand of the building more in Bandar Abbas, with the highest CDD. Using TC coating on the external walls and LETC windows together reduced the energy consumption of the building more in Bandar Abbas. Consequently, integrating these measures can reduce the heating demand of educational buildings more in heating-dominated climates. Also, the simultaneous use of these measures can reduce cooling demand more in cooling-dominated climates.
... As it is stressed to be an impact of urbanization, UHI raises significantly together with rapid new urban development (US Environmental Protection Agency, 2015 andNg, 2009). The warmer air temperature within the dense urban area over the surrounding rural area was reported up to 5.6ºC and reaches the maximum intensity on three to five hour after sunset (Wang, Berardi, & Akbari, 2016;Oke, 1978). As hot, humid regions receive the high intensity of solar radiation throughout the year, UHI effects play a significant role in their urban energy budget. ...
Urban configuration modification is an efficient approach to mitigating Urban Heat Island effect. This study investigates the significant impact of solar radiation and urban wind on microclimate and thermal comfort in the different setting of urban canyon configuration. The Envi-met (V3.1 beta) simulation presents that East-West canyon direction received the worst level of air temperature and meant radiant temperature compared to when the canyon was directed perpendiculars to the wind direction (South East – North West). The finding scientifically demonstrates that in Kuala Lumpur context, with the slow urban wind speed influences, solar radiation plays the significant impact on the microclimate.© 2016. The Authors. Published for AMER ABRA by e-International Publishing House, Ltd., UK. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia.Keywords: Solar radiation; urban wind; urban microclimate, urban simulation
... Our results are also generally in line with Lee et al. [47] for Freiburg (Germany) based on ENVI-met simulations and with Aminipouri et al. [48] based on SOLWEIG for Vancouver (Canada). On the other hand, Wang et al. [49], in his ENVI-met simulations for Toronto (Canada), did not report increased heat stress under the trees during the night. Regrettably, until recently there have been only a few measurements/field experiments evaluating the effect of the trees on thermal exposure during the night [39,50]; however, it is generally acknowledged that trees substantially reduce thermal exposure during the day but may slightly increase heat exposure during the night [4,51,52]. ...
... Previous research has looked at a variety of approaches to reducing UHI and has presented its findings. According to Y. Wang, Berardi, and Akbari (2016), one of the many ways that UHI can be mitigated in ecological restoration efforts is by planting trees in critical areas. Another method is to add a coating to roads or building roofs so that these objects can reflect solar radiation as effectively as possible. ...
Denpasar City is the capital of the province of Bali where anthropogenic activities are most intensive on the island. The study of urban ecological conditions is vital for planning and monitoring the ideal condition of environmentally friendly settlements in the city of Denpasar. This research aims to 1) examine the temperature-related ecological conditions of micro-scale cities based on urban thermal field variance index (UTFVI) values and 2) assess the distribution pattern of NDVI and LST in the city of Denpasar derived from Landsat 8 satellite data. The land surface temperature (LST) and the normalized difference vegetation index (NDVI) were both derived using data from Landsat 9, which was also utilized (NDVI). Following that, UTFVI was categorized using LST. The results show that the greater the UTFVI value, the worse the state of urban ecological degradation and the greater the intensity of UHI, and vice versa. A low UTFVI value of less than 0.005 is spatially distributed throughout all districts and is characterized as an area with good to very good urban ecological quality. This category predominates in the South and East Denpasar Districts, the northern region of the North Denpasar District, and the southern region of the West Denpasar District.
... One of the topics that gained recent scientific interest is the role of greenery in an urban environment and its impact on public health. Greening of the cities is discussed against the problems of air pollution and urban ventilation [2,3], cooling effects for buildings [4], improving their energy balance, and mitigating the heat island effects in cities by reduction of air and surface temperatures [5][6][7]. Urban vegetation enhances biodiversity and provides various ecosystem services [8,9]. Access to green spaces has proven to positively affect human health by relieving stress and improving the well-being of citizens [10][11][12]. ...
Increasing population and urbanization, with climate change consequences, such as rising temperatures, influence public health and well-being. The search to improve the quality of life in cities becomes one of the priority objectives. A solution can be found in the role of greenery in an urban environment and its impact on human health. This opens a path toward experimentation on microclimate green structures that can be inserted into dense urban spaces providing human and environmental benefits. The article proposes an automated greenery design method combined with rapid prototyping for such interventions. A theoretical analysis of the problem preceded the introduction of the method. The research process was developed in accordance with the main objectives of the CDIO framework (Conceive, Design, Implement, and Operate) with the SiL (Software in the Loop) and HiL (Hardware in the Loop) methods. Moreover, the applied test model allows for complex evaluation in order to ensure quality and directions for further development.
... Existing infrastructure like private gardens, road traffic islands and grass verges (Charlesworth 2010), reclaimed parking lots and new public open spaces (City of Melbourne 2020) can help to create a dense network. However, only a few studies (Ng et al. 2012;Santamouris 2014;Wang et al. 2016;Ziter et al. 2019) have presented hypothetical scenarios for city-wide cooling effects. Blue Green Systems connectivity could increase the city-wide daytime cooling effect by 11-19% considering the LST and reduce the diurnal variability of the LST (Li et al. 2017;Sun et al. 2018). ...
Reflected in the growing body of literature, urban heat mitigation is increasingly relevant as cities experience extreme heat, exacerbated by climate change and rapid urbanisation. Most studies focus on urban–rural temperature differences, known as the Urban Heat Island, which does not provide insight into urban heat dynamics. Here, we synthesise current knowledge on spatio-temporal variations of heat sources and sinks, showing that a targeted and absolute understanding of urban heat dynamics rather than an urban–rural comparison should be encouraged. We discuss mechanisms of heat sinks for microclimate control, provide a clear classification of Blue Green Systems and evaluate current knowledge of their effectiveness in urban heat mitigation. We consider planning and optimisation aspects of Blue Green Infrastructure (greenery and water bodies/features), interactions with hard surfaces and practices that ensure space and water availability. Blue Green Systems can positively affect urban microclimates, especially when strategically planned to achieve synergies. Effectiveness is governed by their dominant cooling mechanisms that show diurnal and seasonal variability and depend upon background climatic conditions and characteristics of surrounding urban areas. Situationally appropriate combination of various types of Blue Green Systems and their connectivity increases heat mitigation potential while providing multiple ecosystem services but requires further research.
... Shade in trees is also considered as one of the determining factors in improving thermal comfort to cope with the heat sensation of the day and reduce the mean radiant temperature (MRT). Numerous researches have analyzed the impact of trees as a cooling strategy on urban climate and regulation of human thermal comfort in Asia [63]; H. [18,36,64,65]; L. [66], Europa [67][68][69][70][71] and North America [72]; Y [73]. which points to the undeniable effect of urban trees. ...
As human beings live in an environment where various factors interact and integrate, it seems vital to examine the effects of these factors on environmental perceptions. Outdoor thermal and acoustic environments are the main factors affecting the overall comfort of urban spaces. This research uses measurements and questionnaire surveys to explore the effects of outdoor thermal comfort dimensions on acoustic comfort, emphasizing the plant community in a city park (the El Goli Park of Tabriz, Iran). In this regard, the general comfort of the psychological equivalent temperature (PET) under different conditions of the thermal-acoustic environment has been evaluated and predicted. The results showed that a higher thermal sensation vote (TSV) and PET result in a significant decrease in soundscape quality (SQ), overall impression (OI), and the percentage of reported natural dominant sound (%RNDS), while an inverse trend has been reported in thermal comfort vote (TCV). On the other hand, by increasing TSV and PET, reported loudness (RL) has recorded an upward trend. However, this process was completely reversed in TCV. Furthermore, the analyzes showed that PET has a lower effectiveness compared to TSV and TCV and, it should be stated that the three indicators of thermal comfort did not show any significant relationship with landscape quality (LQ) and sound pressure level (SPL). These findings are important for managing and improving outdoor acoustic comfort and soundscapes, and it is expected that future studies will consider the acquired results in various green urban environments and provide a practical framework for landscape architects and urban planners.
... Compared with traditional microclimate research using measurement instruments experiments, numerical simulation can simulate and predict faster and more accurately. Among the studies with the theme of buildings, Ariane Middel and Yuepeng Wang focused on buildings and studied pollutant dispersion [26] and building energy efficiency [27] in the context of urban heat islands; the research group on the built environment at the Depart-ment of Physics, University of Athens, demonstrated that techniques to increase urban albedo and the use of vegetated roofs can present relatively high heat island mitigation potential [28]. In studies with the theme of human comfort, microclimate simulation software has been used to verify design conjectures and analyze the effects of different scenario configurations, including building orientation, material albedo [26], and vegetation layouts [29], on human comfort in outdoor spaces. ...
With the increasing requirements of healthy habitat environments, landscape microclimates have been widely concerned. To comprehensively grasp the development history and research status of the landscape microclimates in China and other countries, CiteSpace software was used to comparatively analyze and visually present the literature related to landscape microclimates in CNKI and WOS databases for the past 20 years. The results show that: (1) The number of publications on landscape microclimate research shows an increasing trend in China and other countries, and the number of publications increased significantly after 2016. Although the number of publications by Chinese scholars is less than that of foreign scholars, they have developed rapidly in recent years, and their international influence has increased significantly. (2) A positive exchange has been formed among international scholars, and the number of collaborative studies has been increasing. China’s microclimate research has formed relatively stable teams that have conducted numerous studies in the fields of urban communities, street greening, and plant communities, respectively. Although the links between research teams and institutions in China and other countries are relatively close, they still need to be further strengthened. (3) In the past decade, the theoretical system of landscape microclimates has been improved, and the research themes have become more concentrated, but it still has remained close to the early basic research. (4) Future research will remain centered on “mitigating the urban heat island effect” and “optimizing human heat perception”. New topics such as “biodiversity”, “carbon cycle”, and “climate change” have been added. In conclusion, the research needs to continue to explore the evaluation system of microclimates and verify the evaluation index of outdoor thermal comfort for human thermal adaptation in different regions. The standards and systems of human habitat adapted to different regional characteristics should be formed.
... The winter of Haikou, Guangzhou, Xiamen, and Kunming is quite warm. However, under the global warming process, the overheated urban environment in J o u r n a l P r e -p r o o f summer is also an issue for cold-climate cities [97][98][99]. In those cities, the designs of building envelopes should account for the all-year building energy efficiency, especially the period with heating demands. ...
Global warming and the urban heat island effect have led to the deterioration of the outdoor thermal environment and the rise of building cooling demand, calling for urban design with high environmental quality. However, little has been changed in the practice of urban street design. This paper bridges this gap by developing a framework of parametric simulation for design guidance of urban streets with an advanced urban canopy model that can simulate the interactive indoor-outdoor environment. Case studies are conducted at the neighborhood scale for six cities to improve outdoor thermal comfort and building energy efficiency in summer. The influence of street and building design parameters has been investigated based on 31104 simulations. Results reveal the conflict between optimizing outdoor thermal comfort and building energy efficiency. In the majority of the investigated cities, window-to-wall ratio, window type, and street orientation are the most influential parameters. Strategies by adjusting these parameters can significantly improve outdoor thermal comfort, as quantified by thermal stress hours, at a cost of increasing the building cooling load. Planting bigger and denser roadside trees always moderately reduces the thermal stress hours and building cooling load. These results demonstrate the potential of this framework to identify the design trade-offs between thermal comfort and building energy efficiency. The framework can be extended to help designers and policymakers at the early design stage for various cities.
... The 63 main ecological corridors were counted to determine the number of ecological corridors at each level connected to each ecological node. As shown in Table 4, the ecological node of Dongtian Rock in Monkey Island (17) connects four first-level ecological corridors. The regional cumulative resistance is low, and the quality of the ecological corridors is high. ...
Ecological corridor construction is an important support of the current pursuit of high-quality urbanization. Fuzhou is a mountain–water city characterized by a unique spatial structure. However, rapid urbanization has exacerbated the rate of ecosystem fragmentation, negatively impacting the livable living environment. The construction of ecological corridors is of great significance for efforts to restore the broken landscape and form the urban ecosystem as an organic whole in Fuzhou. In the present study, Fuzhou was considered as the study area, and the water, green, and ventilation corridors, as well as surface temperature data, were analyzed using the kernel density analysis method to generate surface-temperature-based ecological nodes. The impacts of various corridors and surface temperatures on the construction of the Fuzhou ecological corridors were assessed using ecological theory, and the ecological resistance surfaces of the influencing factors were obtained. We constructed ecological corridors for the mitigation of the urban heat island in Fuzhou using the MCR model with four levels and then evaluated the network connectivity of the corridors. The results revealed the following findings: (1) The study area comprises 32 ecological nodes, including nine in Minhou County and Changle District, four in Mawei and Cangshan Districts, and two in Gulou, Taijiang, and Jin’an Districts. (2) Fuzhou contains 63 ecological corridors with a total length of approximately 494.65 km. These include 31 first-level (201.16 km), 11 second-level (98.56 km), 14 third-level (129.12 km), and 7 fourth-level (65.81 km) corridors. (3) The degree of closure (α), the point rate of lines (β), the degree of connectivity (γ), and the degree of connectivity (Cr) indexes of the network structure for the ecological corridors were 0.27, 2.03, 0.72, and 0.87, respectively. They indicate that the overall ecological effectiveness of the network is high and can provide a theoretical basis for the construction of ecological corridors in the future.
... Some examples of this include air pollution, rainwater runoff, severe urban heat island effect and biodiversity decline [3][4][5][6]. It also has adverse effects on human and socio-economic development, such as increased physical discomfort and health problems and increased demand for building cooling, resulting in increased energy consumption [6][7][8][9]. Therefore, sustainable measures need to be implemented and incorporated into new and existing development to mitigate the harmful effects of urbanization [6,10]. ...
A vertical greening system is becoming increasingly crucial in resolving the energy crisis and environmental problems in a sustainable ecosystem. Researchers have conducted a comprehensive study on vertical greening systems from technology, functional and architectural perspectives. These include ecological, economic and social functions. Most of the current studies emphasize the benefits of vertical greening systems to the environment, while vertical greening technology and its socio-economic benefits receive insufficient attention. In order to study the vertical greening field in depth, this paper comprehensively and systematically summarizes vertical greening technology and functions. Meanwhile, based on the Web of Science (WOS), CiteSpace was used to analyze the relevant literature in the vertical greening field from 2012 to 2022, to explore the hot spots, development status and future trends of vertical greening technology, and to build a knowledge map in the vertical greening field. The research shows that as a low impact development technology, the vertical greening system has received the most extensive attention in the past few years. Air quality, microclimate regulation and energy have always been the focus and hot issues of people’s attention. The future research directions are cooling effect, active system and indoor space. This study is aimed at promoting the future development of vertical greening system technology and providing reference and direction for researchers, planners and developers, as well as individuals interested in future urban and rural planning.
... For instance, there is a positive correlation between SVF and mean radiant temperature (T mrt ). Measurements by Tan et al. (2013) in Singapore, Kruger et al. (2011) in Brazil, and simulations by Wang et al. (2016) in Canada found that T mrt increases with the SVF. However, the effects of shadows generated by different SVF on thermal comfort are diverse in different weathers or seasons (i.e. ...
People's outdoor thermal comfort under hot conditions have been widely investigated, while the ones in cold environments have not. To address this gap, this paper presented an empirical study for understanding people's thermal sensations and comfort in cold-humid environments of Chongqing, a typical city with cold-humid winter in China. Based on data collected by field measurement and questionnaire survey, we statistically analysed respondents’ wintertime thermal sensation vote, thermal comfort vote, and thermal acceptable vote for microclimate parameters in different scenarios including age group, weather, and space. The results indicate that activity dominated thermal sensations and comfort, and thermal feelings got better with activity intensity. An experience of staying in air-conditioned environments was better to improve thermal sensations, while outdoor duration deteriorated thermal perceptions. Those impacts were intervened by weather, age, and spatial characteristics. Solar radiation and air temperature were critical for thermal perceptions, while respondents’ satisfaction with them was less than that with wind and relative humidity. Wind generally harmed thermal sensation vote and thermal comfort vote, if the wind could make a significant difference. Accordingly, some suggestions were proposed for creating healthy and comfortable outdoor thermal environments, which is imperative to support proper urban planning and design.
... Our results are also generally in line with Lee et al. [47] for Freiburg (Germany) based on ENVI-met simulations and with Aminipouri et al. [48] based on SOLWEIG for Vancouver (Canada). On the other hand, Wang et al. [49], in his ENVI-met simulations for Toronto (Canada), did not report increased heat stress under the trees during the night. Regrettably, until recently there have been only a few measurements/field experiments evaluating the effect of the trees on thermal exposure during the night [39,50]; however, it is generally acknowledged that trees substantially reduce thermal exposure during the day but may slightly increase heat exposure during the night [4,51,52]. ...
We investigate the heat stress mitigation potential of greening strategies in Prague using a configuration of the PALM-4U model that has been rigorously evaluated with measurements. Three greening scenarios were evaluated using the Universal Thermal Climate Index (UTCI). The UTCI reduction effect of broad-leaf or coniferous trees in a complex urban environment was found to be strongly local, with minor domain-average UTCI reductions; −4.1K under tree crowns and −0.6K on average in the neighbourhood as a day-time average, peaking at about twice these values near midday. During daytime the UTCI reduction potential of trees increases with the intensity and duration of solar exposure; −15.1K is the spatial maximum across all scenarios. For trees fully shaded by buildings, UTCI reduction was low (−0.5K as maximum). Tree planting reduces air temperature by more than 5K in some locations under trees, and reduces neighbourhood-average air temperature by up to 0.3K, with cooling peaking in the early evening about 8 h after the corresponding peak in UTCI reduction. Results emphasize the highly localized microclimate effects of trees for pedestrian thermal exposure reduction. The combination of green walls and roofs yielded negligible results in terms of UTCI reduction and only small air temperature effects.
... It follows that this results in a myriad of incomparable planning levels, documents, and policies. To partly address this challenge, and following the example of other studies of UHIs (Wang et al., 2016), two indicative areas per city were selected to focus the research areas. To enable this process, and in line with existing UHI research (Chakraborty et al., 2019, p.4), this selection was based on administrative boroughs. ...
The Urban Heat Island (UHI) is a phenomenon which describes the significant increase in temperature in urban areas compared to the surrounding rural or suburban landscapes. They represent a matter of increasing urgency for policymakers and planners, as they interact synergistically with the climate crisis and lead to significant health and environmental impacts. Marginalised groups are disproportionally affected, as exposure to UHIs, as well as vulnerability to these impacts, are inequitably distributed. Further, planners must consider that some planning interventions themselves can perpetuate or exasperate these climate justice concerns. In Berlin and London, two major cities with (currently) temperate climates and significant levels of urban change, this challenge gains additional relevance. To investigate the extent to which climate justice implications are addressed or exacerbated as part of planning responses to UHIs in the two cities, this dissertation employs a multiple-case study approach based on three methodological strands: Key literature reviews, policy analyses of planning documents and outcomes, and thematic analysis of superordinate planning documents. Findings revealed a lack of recognition and consideration of climate justice aspects through formal planning processes in both Berlin and London, while in London, the UHI was only minimally addressed through this channel in the first place. Often, this was the case despite strong coverage of the relevant topic on a superordinate policy basis. These findings are indicative of a need for continued and deliberate mainstreaming of climate justice in planning, stronger congruity between planning policies and outcomes regarding UHIs, and planners who are willing and able to push the envelope to prevent laying the groundwork for continued injustices. iii Acknowledgements and Declaration
... Process of urbanization, increasing development and dense infrastructure in the cities trap huge amount of solar radiation which can increase the SUHI [63]. Although, SUHI phenomena can be reduced by replacing low albedo to high albedo materials which can make the surface cooler in solar radiation [64]. There is a great agreement that high albedo materials can reduce the intensity of SUHI [65], reflective materials can also help to decrease the intensity [66], rooftops with green surface can have significant impact on reducing SUHI effect. ...
Urbanization changes the existing form of land use and cover (LULC) which can influence the land surface temperature (LST). Therefore, it is important to present the causes of urban heat island (UHI) which is usually linked with anthropogenic activities. There are very few studies on thermal behavior of Korean cities in literature. Hence, in this study we have estimated the LULC of Jeju island and analyzed LST using Landsat (TM/ETM+/OLI) images for the last two decades. The supervised image classification method employed with maximum likelihood classifier algorithm was used to classify the images and thermal band was used to calculate the LST. We have used simplified urban extent (SUE) algorithm to calculate the surface urban heat island (SUHI) and eventually we have correlated the SUHI with mean wind speed of Jeju Island. The results of LULC revealed that urban area increased from 8.69% in 2002 to 20.81% in 2021 and in this period barren land decreased by 34.88% due to urban expansion. Interestingly forest region has been slightly increased which is influenced by decreasing barren land. The accuracy was assessed using confusion matrix for the classified images and results revealed an overall accuracy of 0.87, 0.85 and 0.92 with kappa coefficient of 79.02%, 76.45% and 88.05% for the years of 2002, 2011, and 2021 respectively. The LST of all LULC classes were calculated which revealed the highest temperature for urban class which is followed by barren land. However, the forest cover and water body have the lowest temperature in the island. The intensity of surface urban heat island (SUHI) was increased from 2.47 °C (2002) to 3.10 °C (2021). We have correlated the wind speed and SUHI which revealed that SUHI and wind speed has inverse relationship. The outcome of this research can be utilized by the policymakers, urban planners, architects, and climatologist to develop policy related to climate-resilient cities.
... Some environmental factors such as air temperature and solar radiation in the photo-thermal environment of asphalt pavement can be adjusted by the shade of trees. However, this measure is challenged in high-grade roads due to their large width [36][37][38]. ...
Asphalt pavement is vulnerable to the temperature rising and extremely high-temperature weather caused by climate change. The regulation techniques of asphalt pavement high temperature have become a growing concern to adapt to climate change. This paper reviewed the state of the art on regulating asphalt pavement high temperature. Firstly, the influencing factors and potential regulation paths of asphalt pavement temperature were summarized. The regulation techniques were categorized into two categories. One is to regulate the heat transfer process, including enhancing reflection, increasing thermal resistance, and evaporation cooling. The other is to regulate through heat collection and transfer or conversion, including embedded heat exchange system, phase change asphalt pavement, and thermoelectric system. Then, the regulation techniques in the literature were reviewed one by one in terms of cooling effects and pavement performance. The issues that still need to be improved were also discussed. Finally, the regulation techniques were compared from the perspectives of theoretical cooling effects, construction convenience, and required maintenance. It can provide reference for understanding the development status of asphalt pavement high temperature regulation techniques and technique selection in practice.
... Additionally, urban areas with more vegetation had significantly lower LST values compared to compact built-up areas, indicating that urban vegetation and forestry systems can lower heat load. These results are in alignment with previous studies that analyzed thermal properties in Toronto using Landsat imagery [107][108][109][110]. The study by Rinner and Hussain [107] analyzed the thermal imagery of Toronto on 3 September 2008. ...
Nature-based solutions (NbS) present an opportunity to reduce rising temperatures and the urban heat island effect. A multi-scale study in Toronto, Ontario, Canada, evaluates the effect of NbS on air and land surface temperature through two field campaigns at the micro and mesoscales, using in situ measurements and LANDSAT imagery. This research demonstrates that the application of NbS in the form of green infrastructure has a beneficial impact on urban climate regimes with measurable reductions in air and land surface temperatures. Broad implementation of green infrastructure is a sustainable solution to improve the urban climate, enhance heat and greenspace equity, and increase resilience.
... Given the large transformation and fast-growing population of the GTA, and the expected impacts of climate change, it is crucial to investigate the urban design influences on urban dwellers' heat responses. Moreover, applying heat mitigation strategies that improve the urban environment is essential in the strategic planning for new and existing urban settlements [8,9]. The impacts of green infrastructure and increasing vegetation areas were discussed in the literature on meteorological and environmental variables and human thermal comfort [10]. ...
Green spaces and vegetation cover offer various environmental benefits, including air quality improvements and mitigation of the urban heat island (UHI) effect. Several UHI mitigation policies promoted over the last years in the Greater Toronto Area have targeted the enrichment of the urban vegetation. An integrated approach, including statistical data elaborations and microclimate simulations, is developed in this chapter to look at the impact of increasing the urban green infrastructure on the urban environment, air quality levels, and heat-related health responses. The increase in the urban greenery cover includes the intensification of the urban tree canopy and the incorporation of vegetated façades and green roofs. The proposed enhancements confirm reduction of the ambient air temperature due to applying the proposed heat mitigation strategy.The statistical approach ensures significant correlations between air pollutants' concentration and higher ambient temperatures. Tracking the air quality and health responses due to enhancing the urban microclimate, the results demonstrate a potential reduction all-cause mortalities and cardiorespiratory-related mortalities due to heat resilience and improved air quality levels.
The high temperature in city centres and urban areas than their surroundings, known as the Urban Heat Island (UHI) effect, which causes discomfort to city dwellers in the summer season, is gaining much attention worldwide as the world continues to urbanize. The Urban Heat Island (UHI) is a phenomenon where urban areas are experiencing high temperature than the surrounding rural areas. The current rapid urbanization in India cause of temperature rises, undeniable climatic changes etc. because of it heat island phenomenon occur which call for a need to address the issue of its consequences and awareness. To counterbalance this, various mitigation strategies has been introduced and new technologies are developed which helps in identifying the hot pockets in a city. Due to the seriousness of the problem, extensive research has been done and a lot of literature study of the subject is available. The literature in this domain provides the most up-to-date research methods, concepts, procedures, investigative tools, and mitigation strategies. The aim of this paper is to present state of the art on environmental benefits of UHI mitigation applied at city scale level like benefits of green roof, high albedo material, water body, modification in building envelope and also suggest that future study should concentrate on design and planning characteristics in order to minimize the level of urban heat island and, as a result, live in a better environment.
Particularly for asphalt pavement, where the temperature is a crucial driver in selecting construction materials, premature infrastructure failure and higher maintenance costs might be highly expected with the recently witnessed dramatic changes in climate. Numerous studies highlighted how the recent climate change might result in hazards to transportation infrastructure and affect all types of transportation modes. On the flip side, flexible pavement also contributes to global warming; various studies referred to the significant emissions percentages released by asphalt pavement upon subjection to solar radiation. With that in mind, several studies showed that the environmentally-friendly geothermal systems that mainly depend on heat exchanging with the soil have positive influences on reducing energy consumption, melting the ice on roadways in cold climates, or reducing the ambient temperature and the induced latent heat from the pavement in hot climates. However, very limited studies explored the influence of those geothermal systems on the structural behavior of the pavement concerning the associated distresses with extreme climate changes. In this paper, a critical review concerning climate change has been performed to investigate the structural performance and the associated distress of both conventional and geothermal asphalt pavement. This review underlines several advantageous physical and mechanical characteristics of geothermal pavement, which may recommend this system as a worthwhile alternative to conventional asphalt pavement. The paper also identified future research needs to overcome the shortcomings associated with the structural performance of the geothermo-electrical asphalt pavement.
Outdoor playgrounds are one of the most spaces needed for kids to make different types of activities, and enhancing thermal comfort in such space consist a critical value due to its impact on kids’ health. Unfortunately, the acceleration of urban heat island (UHI) in outdoor spaces, caused by the presence built-up area has affected the temperature of outdoor spaces especially playgrounds. Many researches highlighted the importance of studying outdoor playground materials to achieve kid’s thermal comfort. Nevertheless, analyzing the impact of providing trees on material performance consist a new research perspective. This research highlight on the importance of using trees as natural element to decrease temperature in outdoor playgrounds to achieve kid’s thermal comfort. The aim of this research is to achieve kid’s thermal comfort by enhancing the performance of outdoor playgrounds finishing materials through providing trees. The study will focus on the variation of playground surfaces temperature through simulating different scenario applied in Malek Fahed and Al Biaa garden in Tripoli, Lebanon. The simulation will be applied in subtropical climate using Envi-Met software. The present study provides an overview of outdoor playgrounds finishing materials and its relations with kid’s thermal comfort. Research findings define the performance level of each playground finishing material in chinaberry shading during summer. Results demonstrate that natural surfaces such as sand, grass and stone enhance kids’ thermal comfort more than artificial ones like concrete during summer days.
The high temperature in city centers and urban areas than their surroundings, known as the Urban Heat Island (UHI) effect, which causes discomfort to city dwellers in the summer season, is gaining much attention worldwide as the world continues to urbanize. The Urban Heat Island (UHI) is a phenomenon where urban areas are experiencing high temperature than the surrounding rural areas. The current rapid urbanization in India cause of temperature rises, undeniable climatic changes etc. because of it heat island phenomenon occur which call for a need to address the issue of its consequences and awareness. To counterbalance this, various mitigation strategies has been introduced and new technologies are developed which helps in identifying the hot pockets in a city. Due to the seriousness of the problem, extensive research has been done and a lot of literature study of the subject is available. The literature in this domain provides the most up-to-date research methods, concepts, procedures, investigative tools, and mitigation strategies. The aim of this paper is to present state of the art on environmental benefits of UHI mitigation applied at city scale level like benefits of green roof, high albedo material, water body, modification in building envelope and also suggest that future study should concentrate on design and planning characteristics in order to minimize the level of urban heat island and, as a result, live in a better environment.
Applying urban heat island mitigation techniques requires a holistic understanding of their influences on the urban environment and community health. A novel approach is presented in this chapter by integrating microclimate simulations and correlation analyzes to define the impact of increasing the albedo of urban surfaces on urban health and thermal comfort. The application included enhancing the albedo of urban surfaces including roads, roofs, and building walls for a selected urban microclimate in the Greater Toronto Area. The study aimed to correlate the environmental and health responses by monitoring the historical meteorological and mortality and hospitalization data in the study region and to predict the outdoor thermal comfort due to changing albedo values. The results recommended wise implementation with careful considerations of albedo enhancements regarding urban thermal comfort. The hourly investigation proved the enhanced thermal comfort during specific periods of the day. The reported enhancements in outdoor thermal comfort led to an expected improvement in the instant health responses of the urban inhabitants.KeywordsUrban heat islandHeatwaveAlbedoUrban climateUrban healthMortalityEmergency visitsMicroclimate simulationsCorrelation analysis
Urban heat stress results from increased air temperature, surface temperature, and radiative fluxes including reflected shortwave fluxes and infrared emissions from the urban surfaces surrounding the pedestrian’s body. In the urban context, due to the increased manmade surfaces, reduced vegetated and water surfaces, the adverse effects of this phenomenon on the body’s heat balance are exacerbated. This study quantifies the benefits of greening infrastructure on urban heat stress and its associated mortality impacts by applying a Heat Health Impact (HHI) method to Sydney, Australia. Firstly, meteorological data from all the available weather stations throughout metropolitan Sydney were translated into the Universal Thermal Climate Index (UTCI) for each station—hereafter referred to as the observation study. Secondly, greening infrastructure was implemented throughout metropolitan Sydney in an urban climate model, and again, UTCI was calculated, this time by using air temperature predicted by simulating post-greening scenario—called intervention study. Finally, an extant Health Impact Assessment (HIA) model was applied in order to estimate the change in heat-attributable mortality post greenery intervention. This analysis suggests that urban greenery could reduce between 5 and 8 h of exposure to heat stress during a heatwave day in metropolitan Sydney. Greening could reduce UTCI between 1.3 and 3 °C during daytime in a heatwave, and between 0.3 and 2.7 °C during nighttime. Application of health impact assessment model to UTCI reductions of these magnitudes could reduce the attributable number of deaths by as many as 11.7 per day for Sydney’s current population of 5.7 million.KeywordsUrban heat islandGreeneryUTCIHeat health impact methodHealth impact assessmentHeat-related mortality
The negative impacts of urban heat island (UHI) have attracted more and more academic attention. Currently, few studies have considered the effects of anthropogenic heat emission (AHE) in different urban districts. To explore the spatial and temporal differences in microclimate in high-AHE areas, five high-anthropogenic-heat-emission blocks in Xi'an, China were selected, and the microclimatic indices of air temperature (AT) and relative humidity (RH) were measured in 33 urban points in the five typical urban blocks. Meanwhile, the urban morphological indices of 33 points were calculated in the 20 m and 50 m buffer areas (BAs). Results show that the green cover ratio (GCR), the impervious surface area ratio (ISAR), sky view factor (SVF) and reflectivity (REF) were important variables affecting microclimate. These indices explained up to 35% and 31% of the changes in AT and RH, respectively. In addition, the ISAR should be controlled within 44% and the REF should be controlled above 21.5%, in order to ensure that the maximum AT remained less than 37°C (high-temperature orange warning) inside the block on a typical summer day. This study improves the prediction method of high summer temperatures in high-AHE blocks and provides hints for developing UHI mitigation strategies.
The Weather Research and Forecast (WRF) model is used to simulate atmospheric circulation during the summer season in a coastal region of central Italy, including the city of Rome. The time series of surface air temperature, wind speed, and direction are compared with in situ observations in urban Rome and its rural surroundings. Moreover, the vertical wind profiles are compared to sodar urban measurements. To improve the WRF model’s ability to reproduce the local circulation, and the onset and propagation of the sea breeze, several simulations are carried out modifying the land use and the thermal and physical properties of the surfaces. Based on the results of the correlation coefficient and the RMSE, the heat capacity and albedo are the parameters mostly influencing the daily temperature cycle. Particularly, the temperature in the urban area is reproduced more realistically when the heat capacity is increased. Hence, the best simulations are used to initialize a large-eddy simulation at high spatial resolution to analyze the interaction between the sea breeze and the urban heat island and to investigate the interaction of the sea breeze front with orography and surface roughness. As confirmed by observations collected by in situ weather stations in the surroundings of Rome, the front, entering the city, splits into three branches: (i) a west component in the western flank of the city, closer to the sea; (ii) a north-west component in the northern, inland side, and (iii) a south-west component in the south area of the city.
Urban morphology has significant effects on local thermal comfort. To investigate the correlation between thermal condition and urban spatial configuration, 24 typical scenarios were extracted from complex urban area, and 17 2D/3D indicators were selected to represent urban morphology characteristics. Different statistical approaches were employed to quantify the relationship between the selected indicators and MRT/PET. The results showed: 1) urban morphology exerted more influences on local thermal condition during daytime than at night, leading to the spatial heterogeneity of MRT/PET is much higher in the daytime; 2) the correlations between urban morphology indicators and MRT/PET changed dramatically when using different statistical approaches. This finding highlights the necessity of controlling the effect of building floor area ratio when quantifying the impacts of urban spatial configuration on local thermal comfort; 3) 3D urban morphology indicators were more significantly correlated with local thermal comfort than 2D indicators. Specifically, building floor area ratio and tree canopy coverage ratio were the most important predictor of MRT/PET during daytime and at night respectively. This study could further strengthen our understanding the effects of urban morphology on UHI. It could also offer useful insights to urban planners and decision makers on designing and constructing climate-adaptive urban environment.
Climate change has been a hot topic in recent years. However, the urban microclimate is more valuable for research because it directly affects people’s living environments and can be adjusted by technological means to enhance the resilience of cities in the face of climate change and disasters. This paper analyses the literature distribution characteristics, development stages, and research trends of urban microclimate research based on the literature on “urban microclimate” collected in the Web of Science core database since 1990, using CiteSpace and VOSviewer bibliometric software. It is found that the literature distribution of the urban microclimate is characterized by continuous growth, is interdisciplinary, and can be divided into four stages: nascent exploration, model quantification, diversified development and ecological synergy. Based on the knowledge mapping analysis of keyword clustering, annual overlap, and keyword highlighting, it can be predicted that the research on foreign urban land patch development has three hot trends—multi-scale modelling, multi-factor impact, and multi-policy guidance. The study’s findings help recognize the literature distribution characteristics and evolutionary lineage of urban microclimate research and provide suggestions for future urban microclimate research.
Cities are particularly affected by climate change
impacts. Due to global warming, the frequency and intensity of summer heat
events increases for many cities around the globe. Urban climatological
studies have shown significant positive trends in the number of hot days and
tropical nights. Heat stress is an important health as well as economic
risk. Thus, urban planning needs to adapt to climate change. This requires a
sound scientific analysis of different adaptation measures and management
options, which must be based on appropriate data, models and scenarios to
assess their suitability and efficacy. The goal of this paper is to assess
the suitability of a low cost weather station network consisting of 33
NETATMO weather sensors and ultrasonic anemometers to measure air
temperature, relative air humidity, wind speed and wind direction of a 16 ha
study area in Cologne with high temporal and spatial resolution to support
microclimatological modelling. The temperature and humidity sensors were
calibrated against a research grade reference sensor under laboratory
conditions. In addition, a research grade meteorological station (Campbell
Sci.) was set up in the study area as a reference. The NETATMO sensors were
placed to identify local microclimatic effects due to different surface
types, vegetation and building structures. Using descriptive statistical
analyses and pairwise comparisons, significant differences in the
microclimatic conditions of the various sites were found, which can clearly
be attributed to specific small scale microclimate factors. Significant
differences were particularly identified comparing an avenue and a narrow
street as well as a backyard and an urban park area. The sensors proved to
provide data reliably and with suitable quality to measure microclimatic
effects. The choice of sensors lends itself well for citizen participation,
needed to facilitate climate change adaptation. In our further research, the
data will be used as reference data for microclimatological modelling with
ENVI-met investigating particularly options of mitigating climate change
effects.
Heat mitigating natural elements such as trees, shrubs, grass and water have been broadly studied, while their effects on semi-open spaces have been almost ignored. This paper aims at measuring and comparing the heat mitigating effects of four natural elements in Singaporean courtyards. Four typical courtyard scenarios (each featuring a natural element) are simulated in Envi-met and a comprehensive analysis of air temperature, mean radiant temperature, wind velocity and relative humidity is done to clarify the respective advantages of each natural elements. Daily variation of climate indicators reveal that swimming pools and grass have similar effects on air temperature, mean radiant temperature, wind velocity, relative humidity, and on Physiological Equivalent Temperature, with their differences only being 0.1 °C, 0.3 °C, 0.1 m/s, 0.3%, and 0.3 °C, respectively. Compared with grass, trees do slightly reduce wind velocity by 0.1 m/s, still they significantly reduced the daily Physiological Equivalent Temperature by 2.1 °C. Fountains are better at reducing air temperature by 2.1 °C, compared with swimming pools, but because they also increase relative humidity by 12.8%, they end up performing not so differently from swimming ponds and grass in terms of Physiological Equivalent Temperature.
With continuous acceleration of urbanization, the complexity of the urban geometry leads to great changes in the surface albedo, which further affects the microclimates of urban areas, and gives rise to the urban heat island effect (UHI). The UHI effect results in a series of environmental problems, including frequent occurrence of abnormal weather conditions, pollution of atmospheric environment, increases in building energy consumption and even underlying dangers to urban residents. This paper proposes a critical review on the mechanisms and effectiveness of the major UHI mitigation strategies, i.e. using cool materials, arranging vegetation schemes, incorporating water bodies and optimizing the urban geometry. The review indicates that the ambient air temperature could be reduced by 1.4K∼3.74K, depending on the strategies employed. The previously available mitigation measures are more effective in summer cooling in Tropical, Subtropical and Mediterranean climates. With the increase of H/W (height-to-width) and SVF (sky-view factor), the cooling effects of vegetation, water body and cool materials are better. The review results can provide theoretical guidance to the planning and designing of buildings, and cities, the enhancement of the liveability of urban environment, and the sustainable development of future cities.
Climate comfort is an essential component of destination attractiveness and a key driver of a destination's tourism economy. The measurement of tourism climate via indices such as the Holiday Climate Index (HCI:urban) is thus of great importance to urban locations like Tokyo that, before the Covid-19 pandemic, had burgeoning international tourism profiles. This importance has been amplified by global heating which has caused the already thermally severe Tokyo summertime climate to deteriorate and increase tourism's vulnerability to heat stress. Employing a confidence interval analysis technique, the current research proposes a modification to the HCI:urban such that Tokyo's inherent summertime heat is internalized into the index resulting in a more representative estimate of the city's tourism climate. Calibration of a new rating scale for conditions equal to, or greater than, Humidex 39 has produced a derivative tourism climate index, the HCI:urban Tokyo Summer (HCI:urbanTS), which may be better suited to evaluate Tokyo's tourism climate. Longitudinal data analysis using the derivative index suggests the city's summertime tourism climate should be downrated from the current 'tolerable' to 'intolerable'. Possible means to validate the new index are discussed.
The collection of research conducted over the past decade on urban heat islands and its mitigation strategies reflects the new approaches of scientists, researchers, and government agencies on urban design and planning about the intensity of urban heat islands and their impact on urban texture. This study aims to analyze the trend of research on urban heat islands and strategies to reduce them during the last decade (2010–2020). This review has prepared from 91 research studies and evaluated the main measures to reduce the urban heat island that is commonly used today. In addition, the distribution based on the Köppen–Geiger climate classification, the review of different methodologies, and the funding of research has also been evaluated. Analysis has revealed that studies in humid subtropical (Cfa), hot summer Mediterranean (Csa), and temperate oceanic (Cfb) climates have the largest share among other climatic regions that some measures (urban parks, urban trees, green roofs) have played a critical role for researchers and policy makers more than other influential factors in reducing urban heat islands. It is also noticeable that the relative share of research provided in the four main groups of mitigation measures is almost the same; this similarity can be interpreted to support the argument that lack of funding does not have a significant effect on some mitigation measures.
The relationship between urban morphology and thermal conditions has been subject of several scientific studies and, recently, the role of vegetation in this context has been investigated, aiming to understand its contributions to the improvement of thermal comfort in outdoor environments. This study aimed to understand the relationship between urban vegetation present in the sky view factor (FVC) and thermal comfort. A systematic literature review on the subject was carried out by applying an adaptation of the Preferred Reporting Items methodological approach for Systematic Reviews and Meta-Analyses (PRISMA), seeking to guarantee a transparent and replicable work. The evaluated materials were obtained through database searches using the terms vegetation AND “thermal comfort” AND “sky view factor” and selected by criteria defined by the “PICOS” strategy. parameters referring to the main characteristics of the researches and results achieved, through the reading and tabulation of data with the help of electronic spreadsheets. The results obtained highlight the growing interest in the subject in scientific research, but demonstrate a lack of studies in Latin American countries. It is also observed that most studies indicate a positive relationship between vegetation in the FVC and thermal comfort, with the incidence of negative results at night, winter or interference with wind speed. Such scenarios indicate the need for more studies that seek better understand the particularities of the behavior of urban vegetation in different ways. between climatic and morphological contexts.
Several studies predicted that in case of the continuous rising concentrations of anthropogenic greenhouse gases (GHGs), the gulf region might experience intolerable temperatures to humans. Such terrible weather may have a severe consequence on different vital activities in different Gulf countries, such as the Muslim rites of Hajj in Mecca city. However, supporting the global mitigation efforts would significantly minimize the seriousness of the expected impacts. With that in mind, hot weather was reported as the significant barrier to sustainable mobility in those countries. Their current mobility is heavily dependent on privately-owned fossil-fueled vehicles rather than other sustainable transport choices. This paper reviewed the most recent innovative and solutions to overcome the problems associated with the hot climate. The review focused on the new techniques concerned with reducing the pavement surface temperature and the corresponding decreases in the ambient air temperature, aiming to promote sustainable mobility modes in hot climate cities. The paper also identified future research needs to fulfill each proposed solution's scientific and practical gap and overcome the weather barrier.
This paper focuses on the influence of urban morphology on pedestrian outdoor thermal comfort in Harbin, located in the severe cold region of northeast China. Three typical districts with different urban densities and street layouts were investigated. Field measurement and thermal comfort questionnaire survey were carried out from July 2020 to January 2021. Regression analysis was performed and the neutral physiological equivalent temperature (PET) range was 14.5–22.8 °C. In addition, the PET range was 7.9–27.3 °C when 80% of thermal votes were “acceptable”. ENVI-met was verified and utilized to assess the mesoscale and street-scale impact of urban morphology on thermal comfort in hot and cold seasons. Measurement results shows that the PET variation caused by urban morphology was more significant in the transition season, with the maximum PET difference of 7.6 °C observed at the mid-rise district and the minimum value of 4.4 °C in the low-rise area. Simulation results indicate that the average building height significantly affects the background Ta and PET distribution within the block. Mean radiant temperature (MRT) and PET are highly correlated to sky view factor (SVF) in summer, while in winter, PET is related to SVF only in the low-rise district. Based on the thermal comfort calendar in both hot and cold seasons, shallow and medium canyons (0.5 < H/W < 1.5) are more favorable in severe cold climate, and the optimum streets are near the N–S orientation, followed by intermediate orientations, while deeper canyons (H/W > 1.5) are not recommended due to the lack of solar absorption.
This chapter examines and explains why Canadian cities have taken action
to reduce GHG emissions, while also adapting to and mitigating climate
change. The paper also inventories the activities of select medium to large
Canadian cities (populations between 300,000 and 2.5 million). The paper
offers a simple yet unique approach to analyzing action. Action is classified
as an initiative, output or outcome. Initiatives are policy goals that the city
has made to reduce GHG emissions directly or indirectly, such as improving
building efficiency. Outputs are the specific programs that operationalize
the policy goal (initiative). Outcomes are results or achievements from the
initiatives and outputs. The paper applies each of these categories to three
dimensions of city action — land-use planning; governance; and institutions.
Increasing urbanization and concern about sustainability and quality of life issues have produced considerable interest in flow and dispersion in urban areas. We address this subject at four scales: regional, city, neighborhood, and street. The flow is one over and through a complex array of structures. Most of the local fluid mechanical processes are understood; how these combine and what is the most appropriate framework to study and quantify the result is less clear. Extensive and structured experimental databases have been compiled recently in several laboratories. A number of major field experiments in urban areas have been completed very recently and more are planned. These have aided understanding as well as model development and evaluation.
As highly dense urban areas are also the top energy consumers, the question as to how we can design our cities to be "solar ready", i.e. suitable for successful integration of active and passive solar strategies in buildings, arises. Through a series of insolation simulations of typical urban morphologies found in the city of Toronto, this study will attempt to (i) identify if Toronto is "solar ready", (ii) suggest strategies to overcome obstacles, and (iii) develop new urban formations that maximize insolation levels to promote the integration of solar strategies in our built environments. (C) 2012 The Authors. Published by Elsevier Ltd.
Day to day temperature variation of daily temperature minimum (Tmin) and temperature maximum (Tmax) were examined for five urban–rural pairs of climate stations in North America. Day to day temperature variation was measured by averaging the absolute difference between one day and the previous day for a given time period (e.g., month). For rural sites, day to day temperature variation was typically greater for Tmin than Tmax . The opposite was found for urban locations, with statistically significant stronger signals for larger cities. It is proposed that the difference of these measures (day to day Tmax variability less day to day T min variability) can be used to distinguish between rural and urban stations and as a measure of increasing urbanization. Also, it is suggested that the magnitude of total change in day to day temperature variability (total change in DTD) can be used to decide a suitable urban/ rural pair for any urbanization impact study.
The relationship between the sky view factor (SVF) and the urban heat island (UHI) effect in Montreal is explored, by assessing the effect of SVF on air temperature (T-a) and mean radiant temperature (MRT). The amount of energy consumed by indoor heating and air conditioning is affected by T-a. The value of MRT is the sum of all short-wave and long-wave radiation fluxes absorbed by the human body that affects its energy balance and human thermal comfort. SVF in urban areas affects both T-a and MRT. We used a microscale urban climate model (ENVI-met) and simulated the effect of building geometry in four typical urban districts (each 300 x 300 m(2) in size) in Montreal, on air and human weighted mean radiant temperature (MRThuman (weighted)) at 1.5-m height above the ground. Urban development consideration of a low SVF could mitigate the UHI effect, by decreasing urban temperatures and increasing outdoor thermal comfort. Most UHI studies are carried out for cities in hot and dry climates; however, UHI mitigation can also reduce energy consumption in colder cities, such as Montreal. Results of this analysis can be used in environmental urban planning standards.
This paper examines the relation between urban morphology and windiness. A new concept, catchment area, is introduced to describe this relationship. Wind tunnel measurements of windiness at pedestrian level have been made in simple model cities. The tests show that the velocity is dependent on the overall shape of the city. The maximum velocity is obtained when the street orientation is 45° to the wind direction and not when it is parallell to the wind direction as one intuitively might have expected. The tests show that a street network works as a flow network.
Green roofs and white roofs have been proposed as urban design strategies to reduce low-level air temperatures for the purposes of energy conservation, improved human comfort and reduced smog formation potential. Green roofs partition more solar energy into latent as opposed to sensible heat, while white roofs increase reflection of solar radiation. We integrate an urban surface parameterization (Martilli et al., 2002) in a mesoscale meteorological model (Benoit et al., 1997) to simulate Toronto's low-level air temperature during a fair weather period in August 1997. High resolution land cover data are used to represent the urban surface. Preliminary results suggest green roof and white roof modifications reduce 40 m air temperature by less than 0.1 o C.
The outdoor thermal comfort in an enclosed courtyard has been studied numerically by the three dimensional prognostic microclimate model, Envi-met 3.1. The effect of wind, and shading by different means – galleries, horizontal shading or trees – has been examined. The effect of wind is evaluated by allowing cross-ventilation through openings at 3 and 5 m height above ground level, designed according to the prevalent wind direction. The study was conducted for the hours 11–17 LT during June assuming average climate conditions. The thermal comfort is evaluated by the Predicted Mean Vote (PMV) index.During hot summer days, outdoor comfort is mainly dependent on solar radiation; hence, shading is the best means to improve comfort, while the contribution of wind under all configurations studied was limited and much smaller than the shade contribution.The amount of shade is mainly determined by the courtyard orientation. Inspection of empty enclosed courtyards has shown that an elongated E–W rectangular courtyard has the least shade, and therefore it is the most uncomfortable.When the courtyard is ventilated by openings, hot air and radiation penetrate through them increasing the air temperature and the radiation temperature in the courtyard relative to the conditions obtained in a closed courtyard. Higher openings are less comfortable to stay under, and further decrease the comfort in the courtyard. The addition of trees or/and galleries to the closed courtyard significantly improves the outdoor comfort. Under the assumption of constant building temperature of 25°, the addition of galleries is the most efficient shading strategy.Quantitative results exhibiting these trends are presented for specific configurations and orientations of ventilated and/or shaded courtyards.
Using an atmospheric chemical reaction mechanism applied to air parcels near the Earth`s surface, the sensitivities of ozone (O3) formation rates are quantified for changes in four meteorologically controlled parameters: temperature, sunlight intensity, water vapor mixing ratio, and isoprene concentration. Over a wide range of NO(x) and anthropogenic hydrocarbon concentrations, enhanced photolysis rates and elevated isoprene concentrations are calculated to be the most important factors contributing to increased O3 formation rates in warmer days. These results suggest that the most uncertain yet important meteorological factor controlling regional-scale O3 formation is fractional cloudiness and its impact on photolysis rates.
ABSTRACT Urban areas tend to have higher air temperatures than their rural surroundings as a result of grad- ual surface modifications that include replacing the natural vegetation with buildings and roads. The term “Urban Heat Island” describes this phenomenon.,The surfaces of buildings ,and pavements,absorb solar radiation and become extremely hot, which in turn warm the sur- rounding air. Cities that have been “paved over” donot receive the benefit of the natural cooling effect of vegetation. As the ,air temperature rises, so does the demand for air-conditioning (a/c). This leads to higher emissions from power plants, as well as increased smog formation as a result of warmer ,temperatures. In the United States, we have found that this increase in air temperature is responsible for 5–10% of urban peak electric demand for a/c use, and as much as 20% of population-weighted smog concentra- tions in urban areas. Simple ways to cool the cities are the use of
The study described in this report is part of a project sponsored by the Toronto Atmospheric Fund, performed at the Lawrence Berkeley National Laboratory, to assess the potential role of surface property modifications on energy, meteorology, and air quality in the Greater Toronto Area (GTA), Canada. Numerical models were used to establish the possible meteorological and ozone air-quality impacts of increased urban albedo and vegetative fraction, i.e., ''cool-city'' strategies that can mitigate the urban heat island (UHI), significantly reduce urban energy consumption, and improve thermal comfort, particularly during periods of hot weather in summer. Mitigation is even more important during critical heat wave periods with possible increased heat-related hospitalization and mortality. The evidence suggests that on an annual basis cool-city strategies are beneficial, and the implementation of such measures is currently being investigated in the U.S. and Canada. We simulated possible scenari os for urban heat-island mitigation in the GTA and investigated consequent meteorological changes, and also performed limited air-quality analysis to assess related impacts. The study was based on a combination of mesoscale meteorological modeling, Lagrangian (trajectory), and photochemical trajectory modeling to assess the potential meteorological and ozone air-quality impacts of cool-city strategies. As available air-quality and emissions data are incompatible with models currently in use at LBNL, our air-quality analysis was based on photochemical trajectory modeling. Because of questions as to the accuracy and appropriateness of this approach, in our opinion this aspect of the study can be improved in the future, and the air-quality results discussed in this report should be viewed as relatively qualitative. The MM5 meteorological model predicts a UHI in the order of 2 to 3 degrees C in locations of maxima, and about 1 degree C as a typical value over most of the urban area. Our si mulations suggest that cool-city strategies can typically reduce local urban air temperature by 0.5-1 degrees C; as more sporadic events, larger decreases (1.5 degrees C, 2.5-2.7 degrees C and 4-6 degrees C) were also simulated. With regard to ozone mixing ratios along the simulated trajectories, the effects of cool-city strategies appear to be on the order of 2 ppb, a typical decrease. The photochemical trajectory model (CIT) also simulates larger decreases (e.g., 4 to 8 ppb), but these are not taken as representative of the potential impacts in this report. A comparison with other simulations suggest very crudely that a decrease of this magnitude corresponds to significant ''equivalent'' decreases in both NOx and VOCs emissions in the region. Our preliminary results suggest that significant UHI control can be achieved with cool-cities strategies in the GTA and is therefore worth further study. We recommend that better input data and more accurate modeling schemes be used to carry out f uture studies in the same direction.
Because of the limited daily mobility of tourists, the most important effects of climate on tourism take place at the local level. These effects are significant for both the tourism industry and the owners of holiday homes themselves, but they are also of importance to the planning and design of tourism buildings, recreation facilities and a variety of other issues. With some modification, existing methods for assessing climate in human biometeorology and applied climatology can be applied for tourism climatology (Matzarakis et al., 2004).
Urban forms affect main climatic elements, such as solar radiation, wind speed and air temperature. They are claimed to be the major cause of intra-urban climatic variations. This paper discusses the impact on urban air temperatures of urban configuration variables such as building density, spacing and orientation. The temperature profiles reflect the effect of heat storage, as the higher density experiences warmer temperatures during the afternoon until early morning. Similarly, the daytime temperatures for deeper canyons are cooler, but night-time temperatures are warmer. East-West axis Street proved to be of preferable temperatures in both solstice seasons.
This article describes a joint urban design study by the Berkeley Environ mental Stimulation Laboratory and the Centre for Landscape Research at the University of Toronto. The study analyzed the effect of future development in Toronto's Central Area on street-level conditions of sun, wind, and thermal comfort. The study originated in response to public concern about the quality of the downtown environment and to implementation measures adopted by the Toronto city council in May 1993. The research presented in this article examines the shadowing produced by downtown buildings and recommends procedures and standards for preserving sunlight on Toronto's downtown sidewalks and open spaces. Second, this study considers the effects of buildings on wind conditions at street level. Third, the study evaluates the combined effects of sun and wind conditions on pedestrian comfort. Rather than focusing on just the effects of individual buildings, this research evaluates the cumulative effects of area-wide development.
This book describes the physics and biology of frost occurrence and damage, passive and active protection methods and how to assess the cost-effectiveness of active protection techniques. Nighttime energy balance is used to demonstrate how protection methods are used to reduce the likelihood of frost damage. Simple methods and programs are provided to help predict temperature trends and to help determine the timing for active methods. Plant physiology related to freeze damage and critical damage temperatures for a wide range of crops and ornamentals are presented. Finally, an economic analysis program with examples is included to assist users to evaluate cost-effectiveness of various active methods. Although the book contains considerable technical information, it was specifically written for growers rather than scientists as a practical guide for frost protection.
Key words: Freeze protection, temperature forecasting, weather modification, irrigation, wind machines, sprinklers, heaters, helicopters, ice nucleation active bacteria, cold air drainage, probability and risk, microclimate, heat transfer, humidity
The increasing awareness of the urban heat island (UHI) effect has raised the attention for monitoring and evaluating the outdoor thermal comfort in cities worldwide. The urban microclimate is an important factor for pedestrians' health, but it also affects the urban air quality, the energy use of buildings, citizen wellbeing, and urban sustainability. Issues related to the urban microclimate are becoming more acute in cities given the increasing rates of urban development and construction. In this paper, UHI mitigation strategies in the city of Toronto are assessed. This paper also compares different urban forms according to their orientations, height of wall enclosure, and use of vegetation. The effects of cool surfaces (on the roofs, on the street pavements, or by additional vegetation) are evaluated through numerical simulations using the software ENVI-met. After having obtained the surface temperature, outdoor air temperature, and mean radiant temperature, this study compares three urban areas according to the possible mitigation of net surface radiation and thermal radiative power. The results demonstrate that the duration of direct sun and the mean radiant temperature, which are strongly influenced by the urban form especially in denser areas of the city, play a significant role over the urban thermal comfort. This research supports a sustainable urban development in a cold climate, such as that of Toronto. The final scope of this paper is to suggest design strategies for a more resilient urban planning.
In recent years, there has been a growing interest in the design of courtyards for the microclimatic enhancement of outdoor spaces. However, there is still little knowledge regarding the thermal performance characteristics of courtyards, particularly in hot and humid climates. This study evaluates the ability of unshaded courtyards for providing thermally comfortable outdoor spaces according to different design configurations and scenarios, including the orientations, height and albedo of wall enclosure, and use of vegetation. The software ENVI-met was used as a tool for simulating the thermal performance of courtyards in the hot and humid climate of Kuala Lumpur, Malaysia. The PMV and the number of hours per day that a courtyard could be enjoyed once the proposed design suggestions were implemented are assessed. Likewise, the Physiologically Equivalent Temperature (PET) index allowed to further explore the thermal comfort conditions of courtyards. As a result, guidelines are proposed in order to optimize the design of courtyards towards enhancing their thermal performance characteristics. In particular, the study shows that according to design parameters such as the building height ratio, an abundance in the amount vegetation the courtyard can achieve an acceptable level of thermal comfort for the tropics and may be enjoyed by its users for a long duration of daytime even during the noontime. Finally, this paper stresses that only well designed courtyards may represent a valid option for sustainable built environments.
The paper presents a comparison between two different rating systems to evaluate buildings sustainability: LEED (USA) and ITACA (Italy), thanks to the application of both methods to two residential buildings located in Italy.
The LEED green building rating system encourages an integrated design approach, with a points scheme that allots credits for building design features deemed to improve sustainability, which includes reductions in energy use, improvements in indoor environment quality, protection of the construction site, reduction in water consumption and use of sustainable materials.
ITACA procedure, the environmental quality rating system adopted in Italy, consists of the compilation of a group of worksheets, one for each different performance indicator, at the aim of describing the building environmental quality, including the maintenance of indoor comfort during the entire life cycle.
The chosen buildings are located in central Italy; they are both energy efficient and designed according to the principles of bioclimatic architecture, even if they are characterized by different features. Five common areas (site, water, energy, materials, indoor environmental quality) were identified in order to compare the two methods and to normalize their scores; this original approach can be transfered also to the comparison of other building environmental assessment tools .
The comparison allows to put in evidence the main features of both schemes. Even though the two procedures give different importance to the various areas, the analysis show a proportionality between the respective normalized final scores for the two examined buildings.
This paper provides a comprehensive review of the intra-urban sky view factor (SVF)-temperature relationship. A new approach to reveal the real connection between SVF and air temperature in an entire city is presented. The results found in the literature are rather contradictory, possibly due the fact that previous investigations were limited to the central or specific parts (e.g. inner city, urban canyons) of cities and used few sites and measurements. Comparisons were often based on element pairs measured at selected sites. In some cases areal means were also discussed, but always in connection with one of the variables examined. For comparison, the present study in Szeged, SE Hungary, utilizes a large number of areal means of SVF and air temperature. The values are related to almost a whole city and based on numerous measurements. The results show a strong relationship in the intra-urban variations of these variables, i.e. urban surface geometry is a significant determining factor of the air temperature distribution inside a city if the selected scale is appropriate. Therefore, investigation of a sufficient number of appropriate-sized areas covering the largest part of a city or the entire city is needed to draw well-established conclusions.
Hundreds of large Central Business District (CBD) developments are in planning or development in China and other developing countries. Poor environmental performance in these mega-projects is thought to result from a lack of understanding of basic engineering requirements, especially transport-related. Large energy demand and air pollution are the obvious consequences. While many studies have focused on functional, symbolic and aesthetic requirements of these developments, environmental engineering has in general been neglected. In this research, a typical such large-scale planned CBD in Beijing was investigated just several years after its completion and occupancy. Transportation requirements of the development were measured based on its current use firstly in order to assess how the non-built landscape is used and secondly to assess how a redeployment of the landscape could be used to alleviate ambient environmental problems. By measuring existing demand, we learned to what degree there is over-provision of transportation services and how the current system has correctible inefficiencies. A re-allocation of open space in the area would lead to greater efficiencies in the transport system, but would also allow more space for landscaping. In particular, the thermal environment in the whole area could be substantially improved through the re-allocation of ground-level space. Using thermal modeling to measure the impact of landscape change–street space reductions and an increase in tree cover–it was found that the median air temperature (Ta) could be reduced by as much as 0.5ºC. The environmental advantages increase with time, as the tree canopies grow. In the micro-scaled simulation (300*600m), the Ta was reduced by 1ºC. That is to say, urban summer Ta mitigation could be achieved if such effective modification schemes were expanded from the micro-scale urban community to the whole city. This research provides support for the use of urban landscape modification as a means to improve environmental conditions and energy demands in large-scale commercial urban development especially in China but also in other developing regions. Such landscape adaptation also potentially suppresses motorized traffic demand and contributes to policy development for sustainable urban planning systems.
Green roofs have been proposed for energy saving purposes in many countries with different climatic conditions. However, their cooling and heating potential strongly depends on the climate and building characteristics. In particular, the increase of the thermal capacity of green roofs compared to traditional roofs, if not controlled with insulation, may lead to higher cooling and heating loads. This paper discusses the energy saving potential of green roofs adopting a variable insulation strategy. A system consisting of a plenum located between a green roof and the room underneath and a sensor-operated fan that couples (or decouples) the green roof mass with the indoor environment was developed. The fan is activated and stopped using temperature based rules; the plenum is ventilated only when the fan works, creating a variable insulation system. Four cells with an insulated traditional roof, a non-insulated green roof, an insulated green roof, and a green roof with the variable insulation system have been tested in a hot and dry climate with mild winters over several years. This paper compares and discusses different plenum control algorithms. Results are particularly promising because the variable insulating system proved to adjust the thermal capacity of the roof effectively. In summer, the non-insulated green roof and the green roof with variable insulation system achieved the lowest indoor temperature; in winter, the insulated traditional roof and the variable insulation green roof system achieved the highest indoor temperatures. Measurements are hence compared with simulations. Finally, the energy saving potential of the new green roof system is evaluated. Published by Elsevier B.V.
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
Geographic Information Systems (GIS) and web-based GIS platforms are typically used by large organizations and government agencies for the purpose of data storage, query, analysis, and spatial data mapping. Google Fusion Tables, however, provides cloud-based computing services for data management and easy user collaboration through the Google Maps interface. Fusion Tables are oriented toward smaller organizations that previously were unable to publish data online due to limitations of database knowledge, high cost of start-up, and restrictions on implementation. In this research project, we assess the functionality and limitations of Fusion Tables and associated API as a spatial data management system by programming an interactive web-based mapping platform, the CityTrees.ca Project, designed to showcase the benefits of trees growing on the campus of Ryerson University, Toronto. Specifically, Fusion Tables functionality, such as data storage and manipulation, is used to build a query interface (both attribute and spatial) that permits users of CityTrees.ca to search for and map trees by species, diameter, height, and location. We found that Fusion Tables performed well as a storage medium for our campus tree data, which could easily be explored through our creation of a JavaScript- enabled query tool. Our project provides a unique roadmap for small to medium-sized urban forestry organizations and environmental non-profits seeking to create interactive mapping applications where data privacy and advanced spatial analysis are not fundamental.
The temperature of cities continues to increase because of the heat island phenomenon and the undeniable climatic change. The observed high ambient temperatures intensify the energy problem of cities, deteriorates comfort conditions, put in danger the vulnerable population and amplify the pollution problems. To counterbalance the phenomenon, important mitigation technologies have been developed and proposed. Among them, technologies aiming to increase the albedo of cities and the use of vegetative green roofs appear to be very promising, presenting a relatively high heat island mitigation potential. This paper aims to present the state of the art on both the above technologies, when applied in the city scale. Tenths of published studies have been analysed. Most of the available data are based on simulation studies using mesoscale modeling techniques while important data are available from the existing experimental studies. When a global increase of the city's albedo is considered, the expected mean decrease of the average ambient temperature is close to 0.3 K per 0.1 rise of the albedo, while the corresponding average decrease of the peak ambient temperature is close to 0.9 K. When only cool roofs are considered, the analysis of the existing data shows that the expected depression rate of the average urban ambient temperature varies between 0.1 and 0.33 K per 0.1 increase of the roofs albedo with a mean value close to 0.2 K. As it concerns green roofs, existing simulation studies show that when applied on a city scale, they may reduce the average ambient temperature between 0.3 and 3 K. Detailed analysis of many studies reporting a comparison of the mitigation potential of both technologies has permitted the definition of the limits, the boundaries and the conditions under which the considered technologies reach their better performance, in a synthetic way.
Outdoor thermal comfort in urban spaces is known as an important contributor to pedestrians’ health. The urban microclimate is also important more generally through its influence on urban air quality and the energy use of buildings. These issues are likely to become more acute as increased urbanisation and climate change exacerbate the urban heat island effect. Careful urban planning, however, may be able to provide for cooler urban environments. Different urban forms provide different microclimates with different comfort situations for pedestrians. In this paper, singular East-West and North-South, linear East-West and North-South, and a courtyard form were analysed for the hottest day so far in the temperate climate of the Netherlands (19th June 2000 with the maximum 33°C air temperature). ENVI-met was used for simulating outdoor air temperature, mean radiant temperature, wind speed and relative humidity whereas RayMan was used for converting these data into Physiological Equivalent Temperature (PET). The models with different compactness provided different thermal environments. The results demonstrate that duration of direct sun and mean radiant temperature, which are influenced by urban form, play the most important role in thermal comfort. This paper also shows that the courtyard provides the most comfortable microclimate in the Netherlands in June compared to the other studied urban forms. The results are validated through a field measurement and calibration.
The urbanisation of deserts in Dubai is one way in which this city can expand and explore its full potential. In this piece of research, a case study of the Dubai International Academic City was used as a basis from which to study the importance of planning and orientation of projects in open, unpopulated land. It demonstrates the various alternatives for project orientation relative to the sun and wind, its effects on temperature and wind readings and consequently on outdoor thermal comfort levels. ENVI-met was used to simulate various scenarios generated from the existing base case in both summer and winter. The orientation which best promoted and allowed for higher wind flow through the project was found to record the best outdoor Predicted Mean Vote levels, approaching a neutral state. The findings of this research may be used for setting up regulations regarding the planning of desert areas in Dubai on the basis of early assessment of designs.
Courtyard vegetation, high albedo surfaces, and courtyard ponds were investigated as potential heat mitigation strategies using field measurements and simulations in a university campus environment. The investigation was performed during a summer period in the temperate climate of Portland, Oregon, USA. In a comparison of seven locations on the campus, the maximum park cooling island effect recorded was 5.8 °C between the heavily treed campus park and a nearby parking lot with asphalt pavement. Simulations of courtyards with vegetation and a water pond showed 1.6 °C and 1.1 °C air temperature reduction, respectively. Changing the albedo of the pavement in a bare courtyard from 0.37 (black) to 0.91 (white) led to 2.9 °C increase of mean radiant temperature and 1.3 °C decrease of air temperature.
Green roofs have been proposed for sustainable buildings in many countries with different climatic conditions.
A state-of-the-art review of green roofs emphasizing current implementations, technologies, and
benefits is presented in this paper. Technical and construction aspects of green roofs are used to classify
different systems. Environmental benefits are then discussed mainly by examining measured performances.
By reviewing the benefits related to the reduction of building energy consumption, mitigation
of urban heat island effect, improvement of air pollution, water management, increase of sound insulation,
and ecological preservation, this paper shows how green roofs may contribute to more sustainable
buildings and cities. However, an efficient integration of green roofs needs to take into account both the
specific climatic conditions and the characteristics of the buildings. Economic considerations related to
the life-cycle cost of green roofs are presented together with policies promoting green roofs worldwide.
Findings indicate the undeniable environmental benefits of green roofs and their economic feasibility.
Likewise, new policies for promoting green roofs show the necessity for incentivizing programs. Future
research lines are recommended and the necessity of cross-disciplinary studies is stressed.
