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The Urban Heat Island Effect in the City of Toronto
Abstract
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.
... Different applications of green infrastructure can regulate temperature. Various phenomena collaborate on green roofs to regulate temperatures and provide a cooling effect on the urban microclimate [51,52,55]. Green roof foliage and vegetation provide shade and absorb thermal energy through photosynthesis while promoting a cooling effect through evapotranspiration [56]. ...
... Green roofs and urban vegetation function as an effective UHI mitigation strategy through their cooling effect on the urban microclimate [51,52,55]. The application of urban vegetation and forestry has been shown to effectively regulate near-surface air temperatures and LST by cooling the air below through shading and evapotranspiration [60]. ...
... Research on green infrastructure and temperature thus far has had a limited focus on single applications and individual benefits [49,55,63,64]. Building on the work undertaken by Anderson and Gough [6], this study evaluates the potential of different applications of green infrastructure to regulate near-surface air temperatures and LST at both the micro and mesoscale in Toronto, Ontario, Canada. ...
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.
... Other applications of green infrastructure such as urban vegetation strategies like tree and shrub plantings in urban corridors have also been shown to be effective in the reduction of temperatures (Nowak et al. 2006;Hall et al. 2012;Weber et al. 2014;Anderson 2018). Green roofs and urban vegetation can also function as an effective urban heat island mitigation strategy through their cooling effect on the urban microclimate (Wang et al. 2015;Berardi 2016;Jandaghian and Berardi 2019). ...
... Research on the temperature regulation benefits of green infrastructure has typically had a narrow focus on single applications and individual benefits (Alexandri and Jones 2008;Hall et al. 2012;Wang et al. 2015;Hoelscher et al. 2016). Research on the potential of surface temperature regulation has been limited to specific applications of green infrastructure; however, an evaluation across different applications simultaneously has not been undertaken. ...
... The potential of green infrastructure writ large to mitigate local environmental stressors such as heat waves resulting from higher Reported are control and treatment (GI) temperatures, their difference (delta), and their standard deviations (STD all in°C temperatures is significant. These results are consistent with previous work (Alexandri and Jones 2008;Hall et al. 2012;Wang et al. 2015;Hoelscher et al. 2015;Susca et al. 2011;Liang et al. 2014), which has focused primarily on single applications of green infrastructure. Our results complement other work undertaken in Toronto, Ontario, Canada, that evaluates the impact of different treatments including specific applications of green infrastructure (i.e. ...
The application of green infrastructure presents an opportunity to mitigate rising temperatures using a multi-faceted ecosystems-based approach. A controlled field study in Toronto, Ontario, Canada, evaluates the impact of nature-based solutions on near surface air temperature regulation focusing on different applications of green infrastructure. A field campaign was undertaken over the course of two summers to measure the impact of green roofs, green walls, urban vegetation and forestry systems, and urban agriculture systems on near surface air temperature. This study demonstrates that multiple types of green infrastructure applications are beneficial in regulating near surface air temperature and are not limited to specific treatments. Widespread usage of green infrastructure could be a viable strategy to cool cities and improve urban climate.
... The role of green roofs in mitigating the effects of urban heat islands has been previously discussed [4][5][6][7][8][9][10][11][12][13]. The greatest contributors to urban heat islands are large asphalt or concret areas with low albedo values, the reduced percentage of vegetation in urban environments, high buildings and narrow streets that modify the direction and speed of winds and create urban canyons, or any combination of these factors, as well as activities in urban environments that generate heat (HVAC systems, transport and other anthropogenic processes and factors). ...
... The use of green roofs is one of the strategies to climate change adaptation in cities, as described previously [5,14,15]. Vegetative roofs are one part of the system of green infrastructure in cities. Green infrastructure has been studied as a strategic approach and part of the solution for reducing heat and pollution in urban environments [5,6,10,15,16]. With regard to the natural cooling effect through the process of evapotranspiration, it was concluded that green infrastructure should be strategically implemented in urban environments and utilized in urban and architectural design. Green infrastructure is the most effective tool in the fight against climate change [3,7,14]. ...
... The effects of utilizing green roofs on city microclimates and reductions in energy requirements have been investigated in different climatic areas: Toronto [5,6], Chicago [19], Portland, Chicago, Atlanta, Huston [22], London [23], Lisbon [24], Athens [25,26], cities in the Netherlands [27], cities in Northern Spain [28], Rome [29], Palermo [30], Teramo [31], Catania [32], Hong Kong [33], Kuala Lumpur, Singapore and Hong Kong [8], Kawasaki [20], Hangzhou [34], Adelaide [10], Melbourne [11], Guangzhou and Frankfurt [35], plus others. Vegetative roofs contribute differently to microclimate modification in different climatic zones. ...
The effect of extensive and intensive green roofs on improving outdoor microclimate parameters of urban built environments is currently a worldwide focus of research. Due to the lack of reliable data for Belgrade, the impact of extensive and intensive green roof systems on mitigating the effects of urban heat islands and improving microclimatic conditions by utilizing high albedo materials in public spaces were studied. Research was conducted on four chosen urban units within existing residential blocks in the city that were representative of typical urban planning and construction within the Belgrade metropolitan area. Five different models (baseline model and four potential models of retrofitting) were designed, for which the temperature changes at pedestrian and roof levels at 07:00 h, 13:00 h, 19:00 h on a typical summer day and at 01:00 h the following night in Belgrade were investigated. ENVI-met software was used to model the simulations. The results of numerical modeling showed that utilizing green roofs in the Belgrade climatic area could reduce air temperatures in the surroundings up to 0.47, 1.51, 1.60, 1.80 °C at pedestrian level and up to 0.53, 1.45, 0.90, 1.45 °C at roof level for four potential retrofitting strategies, respectively.
... The amount of attention given to the urban microclimate is substantiated when taking in to consideration that the Toronto Public Health Department already determined the heat-related mortality in Toronto to be at a level of 120 deaths per year; a rate that is predicted to double by 2050 [6]. In fact, over the last two decades, the Natural Resources Canada has used air temperature and surface temperature measurements collected from satellite imagery to characterize the microclimatology across Toronto and to assess the effect of UHI mitigation policies [7,8]. Thermal images of surface temperatures have shown the increasing UHI effect over Toronto [9], and the importance to promote more stringent policies for its mitigation [10,11]. ...
... In this paper, the model was simulated from 4 a.m. of August 15th to 4 a.m. of August 16th, using the local weather station data reported in Table 1 as initial boundary conditions. The effect of the green roofs on the microclimate in the winter was not investigated due to prior studies that showed negligible impact of the vegetation on winter outdoor comfort in Toronto [8]. ...
... This observation could also be attributed to the differences in building heights, as the JOR building has a higher sky view factor (SVF), and therefore more heating due to direct solar radiation during the day and greater cooling at night. Many studies have reported the connection between SVF and air temperature [8,[62][63][64]. ...
... In Brazil, India and China impervious surfaces occupy 0.39%, 1.61% and 1.85% of their respective total land area (Shen et al., 2016). Thermally massive structures installed in the cities absorb, store and re-radiate the extra solar energy per unit area as compared to the green (vegetated) surfaces that dominate their rural surroundings (Wang et al., 2015;Chen, 2013). The proportion of latent heat transfer through evaporation reduces due to the increased surface runoff from the impervious surfaces of roads, pavements and buildings (Sodoudi et al., 2015). ...
... The studies so far which address the UHI mitigation issues through micro-thermal modeling and simulation of urban built environment have been wide-ranging for temperate cities (Rosenfeld et al., 1995;Rizwan et al., 2008;Mirzaei and Haghighat, 2010;Gago et al., 2013;Santamouris, 2012, Santamouris, 2013Akbari and Kolokotsa, 2016). Cool roof, cool pavement and green coverage have been identified as the most popular well-researched alternatives to moderate temperate UHIs at the diurnal scale (Wang et al., 2015;Estrada et al., 2017). Majority of the tropical UHI studies are, however, oriented towards assessment of UHI magnitude, few of these account for the contributing factors (Roth, 2007;Emmanuel andSteemers, 2018a, Emmanuel andSteemers, 2018b). ...
Tropical cities aremore susceptible to the suggested fall outs fromprojected globalwarming scenarios as they are
located in the Torrid Zone and growing at rapid rates. Therefore, research on the mitigation of urban heat island
(UHI) effects in tropical cities has attainedmuch significance and increased immensely over recent years. TheUHI
mitigation strategies commonly used for temperate cities need to be examined in the tropical context since the
mechanism of attaining a surface energy balance in the tropics is quite different from that in the mid-latitudes.
The present paper evaluates the performance of four differentmitigation strategies to counterbalance the impact
of UHI phenomena for climate resilient adaptation in the KolkataMetropolitan Area (KMA), India. This has been
achieved by reproducing the study sites, selected fromthree different urbanmorphologies of open low-rise, compact
low-rise and mid-rise residential areas, using ENVI-met V 4.0 and simulating the effects of different mitigation
strategies- cool pavement, cool roof, added urban vegetation and cool city (a combination of the three former
strategies), in reducing the UHI intensity. Simulation results show that at a diurnal scale during summer, the green citymodel performed best at neighborhood level to reduce air temperature (Ta) by 0.7 °C, 0.8 °C and 1.1 °C,
whereas the cool city model was the most effective strategy to reduce physiologically equivalent temperature
(PET) by 2.8° – 3.1 °C, 2.2° – 2.8 °C and 2.8° – 2.9 °C in the mid-rise, compact low-rise and open low-rise residential
areas, respectively. It was observed that (for all the built environment types) vegetation played themost significant
role in determining surface energy balance in the study area, compared to cool roofs and cool pavements.
This study also finds that irrespective of building environments, tropical cities are less sensitive to the selected
strategies of UHImitigation than their temperate counter parts, which can be attributed to the difference inmagnitude
of urbanness.
... The urban surface thermal environment has received considerable attention in recent years, owing to its profound influence on biodiversity and environmental function, in addition to citizens' well-being and urban sustainability [1][2][3]. Land surface temperature (LST) is one of the key parameters in land surface physical processes [4], and is closely related to the urban impervious surface, vegetation cover, building density, water area, surface energy budget, and urban heat island (UHI) effects [5,6]. Satellite observation provides abundant, consistent, and continuous data pertaining to LST fluctuations, and the field has witnessed considerable progress through the use of thermal infrared remote sensing in terms of methodological and analytical development [7][8][9][10][11][12]. ...
... Moreover, overlapping shadows cause a decline in LST within the shaded area at daytime. The impervious surface in the urban central area dissipates heat rapidly by longwave radiative emissions, causing the LST drop sharply at nighttime, creating an urban cooling island (UCI) effect [1,56]. These phenomena highlight the relative complexity of city center environments, and indicate that several factors affect the fluctuation trends of LST in relation to NTL intensity, including UHI, UCI, and DMSP/OLS NTL imagery light saturation effects. ...
Nighttime light (NTL) imagery, as an excellent data source for monitoring urban development and human activity, has been used in research concerning land surface thermal environment. However, previous studies have only taken NTL data as a measure of urbanization degree or to obtain intermediate products for LST studies, such as urban impervious surface area and building density. Few studies have systematically analyzed the spatial and temporal variations of different light levels and surface temperatures. In this study, a LST–NTL rank correlation model was constructed based on MOD11C3 and DMSP/OLS data to analyze the characteristics and trends of the relationship between LST and NTL, during both daytime and nighttime over China in 2012. The findings revealed a strong positive correlation between NTL level and LST, with the peak correlation (R² > 0.85) observed during July–September, which indicated that, with the increase of the light intensity, the LST has an overall upward trend. The trend was relatively more stable during nighttime (variation range of R² was 0.3) than during daytime (variation range of R² was 0.44). Moreover, it was greatly enhanced without considering NTL intensity saturation pixels in the NTL partition system, and was further improved after removing pixels from urban centers, which was particularly evident at nighttime. This provided evidence that NTL intensity can be a good indicator for the distribution of urban thermal environment, particularly outside the urban centers.
... Such opportunities include play, physical exercise and athletic activities, relaxation, social interaction, and reprieve from urban noise and heat. In addition, ecosystem services and vegetation cover from parks mitigate air pollutants, reduce surface temperatures and the urban heat island effect, mitigate flooding, support biodiversity, and increase community resiliency to climate change [1][2][3][4]. Urban parks include forested and vegetated areas, playgrounds, recreational fields, community gardens, and urban squares. Park investments can include developing new parks or expanding parks, improving the quality of parks and amenities, or offering new programs and services. ...
The allocation of resources towards the development and enhancement of urban parks offers an effective strategy for promoting and improving the health and well-being of urban populations. Investments in urban parks can result in a multitude of health benefits. The increased usage of greenspace by park users has been linked to positive physical and mental health outcomes. Additionally, the expansion of greenspace in urban areas can mitigate harmful impacts from air pollutants, heat, noise, and climate-related health risks. While the health benefits attributed to urban parks and greenspaces are well documented, few studies have measured the economic value of these benefits. This study applied a novel ecohealth economic valuation framework to quantify and estimate the potential economic value of health benefits attributed to the development of a proposed park in the downtown core of Peterborough, Canada. The results indicated that development of the small urban park will result in annual benefits of CAD 133,000 per year, including CAD 109,877 in the avoided economic burden of physical inactivity, CAD 23,084 in health savings associated with improved mental health, and CAD 127 in health savings attributed to better air quality. When including the economic value of higher life satisfaction, the economic benefit is more than CAD 4 million per year. The study demonstrates the value of developing and enhancing urban parks as a strategy to improve population health and well-being, and as a means of cost savings to the medical system.
... Health Canada also reports a heat wave if the local temperature-humidity index (Humidex) in the above-mentioned region reaches 40 or more for at least 2 consecutive days. Meanwhile, urban heat island effects combined with climate change issues are increasing the concerns in countries like Canada, traditionally considered less vulnerable to heat waves (Berardi et al., 2020;Berardi and Wang, 2016;Wang et al., 2015). ...
The combined effects of heat events and poor air quality conditions can severely affect population health. A novel correlational method was developed to assess the impact of the short-term variations of environmental variables (air pollutants and ambient conditions) on community health responses (mortalities and emergency department visits). A multi-dimensional clustering approach was proposed by combining hierarchical and k-means clustering to promote flexibility and robustness to improve the correlation procedure. The study focused on the health records of the elderly population and people diagnosed with cardiorespiratory causes. The study investigated multiple health records on different levels of investigation: total, elderly, cause-based, and elderly cause-based records. The developed method was validated by investigating the short-term impact of ambient air temperature , relative humidity, ground-level ozone, and fine particulate matter on the health records during hot and warm seasons in the municipalities of Mississauga and Brampton, Peel Region, Ontario, Canada for 15 years. The analysis confirmed the association between moderate levels of environmental variables and increased short-term daily total deaths and emergency department visits, while the elderly sector showed higher vulnerability to environmental changes. Furthermore, the association with extreme heat conditions and poor air quality levels was affirmed with cause-based mortalities and emergency visits; the correlation was strongest with elderly cause-based health records. Findings confirm that cardiorespiratory patients, especially elderly people, were at the greatest risk of poor environmental conditions.
... As a result, UPI-related accelerated aerosols can cause substantial radiative forcing in the metro atmosphere. On the one hand, additional aerosols can scatter more light energy back into space, lowering the amount of solar radiation reaching the urban surface (Wang et al. 2015). On the other hand, the accelerated aerosols can collect more of the Earth's emitted electromagnetic rays and re-emit additional signal amplification radiation to the city floor. ...
Increasing temperatures in urban areas cause an increase in air conditioning demands, elevated pollution levels, and may modify precipitation patterns. Therefore, many environmental, economic, and social considerations are associated with the urban heat island (UHI) effect, directly affecting the residents of a city’s comfort and health. A detailed analysis regarding the formation of UHIs with the help of land surface temperature (LST) image mapping was carried out in the present study. The results show the presence of nocturnal UHI formation over the Delhi city during the entire study period with an average surface UHI intensity (SUHII) of 9.5 K, whereas an inverse surface UHI (SUHI) effect was observed during the day period. Also, a detailed analysis regarding the formation of urban pollution island (UPI) with the help of aerosol optical depth (AOD) image mapping was done in the present study. By comparing SUHII and urban pollution island intensity (UPII) over the study area, it has been noticed that there is no significant correlation between SUHII and UPII. During summer day and nighttime and winter day and nighttime, there were significantly lower values of R2 recorded in a range between 0.002 and 0.48. Rising temperatures due to UHI formation can cause aerosol particles to disperse beyond higher atmospheric boundaries by facilitating rapid mixing, but it does not show any proper trend during the study period. During the day period, soil or barren land contributes to higher LSTs in rural areas, leading to an inverse UHI effect, or cool island effect. Instead of AOD, land use and land cover (LU LC) change shows a good relationship with diurnal LST variations. Higher road density (RD) value regions and the densely built-up areas have shown higher values of LST and are responsible for the nocturnal UHI effect over the study area during both summer and winter.
... The decrease of LST is from the highest -43°C to 39°C-below the average. ANALYTICAL STUDY OF THE IMPACT OF GREENERY AND PUBLIC SPACE DISTRIBUTION ON LAND SURFACE TEMPERATURE IN MID-SIZE CITIES OF POLAND 445 The cooling effect of vegetation seems effective -1°C over each 3% of vegetation coverage what is higher than was noticed in Toronto (Wang et al., 2015). The vegetation in our research includes only above 0.5 meters in height as a result of methodology, so it includes mainly trees and higher bushes. ...
... Specifically, a significant reduction in surface temperature (5°C) and PET (average of 2.2°C) has been observed in Chania (Tsilini et al., 2015) and Stuttgart (Ketterer and Matzarakis, 2015), respectively. Tehran has witnessed a reduction in nocturnal UHI by 0.92°C due to urban greening (Sodoudi et al., 2014), while a 10% increment of greening in Toronto can reduce air temperature and PET up to 0.8°C (Wang et al., 2015c). A positive correlation of urban greening and sky view factor (SVF) has been seen in Hong Kong, where a high SVF resulted in a reduction in air temperature by 1.5°C. ...
Urban environments lie at the confluence of social, cultural, and economic activities and have unique biophysical characteristics due to continued infrastructure development that generally replaces natural landscapes with built-up structures. The vast majority of studies on urban perturbation of local weather and climate have been centered on the urban heat island (UHI) effect, referring to the higher temperature in cities compared to their natural surroundings. Besides the UHI effect and heat waves, urbanization also impacts atmospheric moisture, wind, boundary layer structure, cloud formation, dispersion of air pollutants, precipitation, and storms. In this review article, we first introduce the datasets and methods used in studying urban areas and their impacts through both observation and modeling and then summarize the scientific insights on the impact of urbanization on various aspects of regional climate and extreme weather based on more than 500 studies. We also highlight the major research gaps and challenges in our understanding of the impacts of urbanization and provide our perspective and recommendations for future research priorities and directions. Citation: Qian, Y., and Coauthors, 2022: Urbanization impact on regional climate and extreme weather: Current understanding, uncertainties, and future research directions. Adv. Atmos. Sci., https://doi.org/10.1007/s00376-021-1371-9. Article Highlights: • As urban areas expand and populations grow, we urgently need to better understand cities and their interactions with weather and climate. • Urbanization can impact heat waves, atmospheric moisture, clouds, wind patterns, air pollution, boundary-layer, precipitation, and storms. • Research gaps due to complexity of urban areas and deficiencies in current methods are identified and future priorities are highlighted.
... The evolution of this area reflects the complex processes by which human activities transform surface structure and function, which in turn affect the spatiotemporal evolution of the surface thermal landscape [12]. Therefore, reviewing the mechanisms of the spatiotemporal changes in this region's surface thermal landscape is very important to formulating measures to alleviate the urban heat island effect [13][14][15], and to thus improve the modern urban ecological environment [16,17]. ...
Advancements in the integrated development of the Yangtze River Delta are changing the structure and function of the surface thermal landscape and triggering a series of ecological and environmental problems. Therefore, examining the spatiotemporal differentiation characteristics and evolution laws of this land surface thermal landscape has great theoretical and practical significance in the context of optimizing functional zoning and realizing the harmonious development of the economy, society and nature. The paper uses the LST (land surface temperature) data retrieved by MODIS (MOD11A2) remote sensing satellites in 2007, 2010, 2013, 2016 and 2019 to extract a land surface thermal rating map of the Yangtze River Delta region, and to analyze the spatiotemporal differentiation in the land surface thermal landscape, combining of the land surface thermal landscape strip profile and thermal landscape pattern indices. The results show that the LST in the Yangtze River Delta region has increased in the past 12 years, the proportion of middle-, sub-high- and high-temperature zones increased by 33.42%, and the high-temperature zone has gradually extended into inland areas. The high-temperature zones in the areas surrounding core cities such as Shanghai, Nanjing, and Hangzhou have expanded. The corridor effect of thermal changes on the surface is obvious. The degree of aggregation in the lower-temperature areas has gradually decreased. The degree of aggregation in the higher-temperature regions has increased. The patch types of thermal landscape pattern increase, and the distribution of landscape area among various types tends to be even. this trend is most significant in optimized development region.
... The formation of the urban heat island phenomenon in cities is contributed by several factors, and lack of urban vegetation is one of the factors leading to the increase of urban temperature (Grimm et al., 2008;Zhou et al., 2011). Urban greening has been proved to alleviate the adverse impacts of increased temperatures resulting from urbanization and climate change (Yu and Hien, 2009;Bowler et al., 2010;Wang et al., 2015). Extensive studies found that green urban infrastructure (GUI, e.g. ...
There is in general good awareness of the potential role of green roofs to regulate urban thermal environments, but a lack of effective spatial modeling of this cooling effect for a given roof greening scheme at the city scale. This study proposes a simplified and feasible approach to simulate the cooling effect provided by green roofs as a mitigation option to combat urban heat island effects in high-density urban areas. In this study, we established a spatial model of the cooling effect of green roofs, which integrated remote sensing methods and a statistical model based on the law of diminishing marginal utility of the cooling efficiency of green roofs (DMUCE) deduced from previous studies. A case study in Xiamen City, China demonstrates the applicability and implications of the model. Our modeling clearly simulated the size and strength of the urban cool island and its variation under different green roof scenarios. We found that green roofs play an important part in moderating the thermal environment in areas where larger green spaces and waterbodies are largely absent. When the proportion of green roofs is implemented at scale, roofs that are only partly green can also create some extra cool islands (not merely normal islands) in high-density urban areas, equivalent to small green spaces and waterbodies. The sensitivity analysis of the cooling effect indicated that the maximum potential benefit of heat island reduction ranged from 4.04 km² to 9.75 km² when the coverage of green roofs was extended to the entire Xiamen Island. Besides, our results suggested that all proposed strategies would not remarkably moderate the thermal environment in the north of Xiamen Island, where urban planners should pay more attention in the future.
... In addition, the ENVI-met software has been widely used for simulating the impact of buildings and urban variables on outdoor microclimate parameters such as air temperature, wind speed and relative humidity [3] [43] [45]. With respect to the urban and design variables, the software had been used for investigating the impact of green vegetation and green roofs [50] [52] [53]. Furthermore, the software allowed the effect of different types of surface material and albedo to be tested on the outdoor microclimate parameters and UHI [51] [54]. ...
Urban development in urban areas accommodates a high concentration of human activities. The constant state of evolution in these urban areas is accompanied by environmental problems, including the formation of the Urban Heat Island effect (UHI), where the air is hotter than in rural areas. This research investigates where they occur the factors that contribute to the UHI by reviewing the previous literature on the subject and dividing the factors according to what has created them: 1) the wider environment, 2) their general urban surroundings, and 3) the specific buildings around them. Locally, it has been found that very few publications have covered the factors that compose UHI. Therefore, this study aims to support previous literature on this subject by adopting a novel approach and using two research methods to rank the most important UHI factors. In the first stage of the study, on the subjective basis of experts’ opinions, the Analytical Hierarchy Process (AHP) was used to rank the UHI factors and, thus, identify the most important factor in each category. In the second stage of the study, this process was extended to test the hierarchy of UHI factors in an existing courtyard, which included most of the relevant factors in its design and construction. After developing proposed scenarios in the courtyard, ENVI-met simulation software was used to test and evaluate each factor. The scenarios were developed around factors from the building category and this resulted in another ranking, based on each factor’s contribution to reducing the surface temperature. The more effective factors were together applied to three optimized scenarios and finally the outdoor surface temperature was reduced by 2.45 ᵒ C, partly by the best combination of the most effective factors to be identified.
... Similar studies done by Susca, Gaffin, & ity, found an average of 2°C difference of temperature between the maximum and minimum vegetated areas. A maximum 0.8°C reduction of air temperature and mean radiant temperature if urban greening is increased at 10% (Wang Y, Berardi U, Akbari H., 2015). ...
Climate change is a threat to the world. Problems resulting from climate
change such as global warming, floods, environmental pollution, high carbon
dioxide emissions, and loss of biodiversity may be solved by the
implementation of green roofs. Green roof benefits the environment, economy,
aesthetics, and recreation, and proven through studies conducted
from around the world. This paper reviews the existing literature on green roof
benefits and performance and specifically focuses on their potential to address
climate change issues. A review of significant literature on green roof
performance and benefits is the method of this study. From the review, it is
proven that green roofs have the potential to reduce problems related to climate
change. The depth of a green roof substrate is a key factor that can optimize
potential benefits. Thus, intensive types of green roofs provide a significant
contribution towards reducing storm water runoff; mitigate the urban heat
island effect and pollution; increased biodiversity; and carbon sequestration.
Local research is highly encouraged in mitigating climate change because the
optimal performance of green roofs is subject to local climate and conditions.
... The main reasons for this effect are population growth and the rapid increase of urbanization, which may cause an accumulation of warm air, as well as warmer surface temperatures. The urban microclimate is important for pedestrians' health, but it also affects air quality, citizen well-being, urban sustainability and the energy use of buildings (Wang, Berardi, & Akbari, 2015). ...
The urban microclimate is influenced by many factors which trigger the well-known Urban Heat Island (UHI) phenomenon. Different approaches have been developed in the literature for estimating urban temperatures, but a compromise is always needed, either spatial or temporal. To solve this issue, this work presents a new way for estimating urban temperatures with a fine spatial resolution (even specific streets) while also keeping a high temporal resolution (hourly time-steps) for prolonged periods. This is done by developing an empirical model, based on the measurements of a reference weather station and data taken from mobile transects.
The proposed method was tested in Seville (Spain). The validation was done comparing the prediction of the model with the measurements of a fixed temperature sensor, from the 7th of June 2019 until the 7th of December 2019 (4390 hours). The results showed a high R² coefficient of 0.976 and a low RMSE of 1.21, improving the accuracy of previous literature for estimating urban temperatures. The methodology is applicable for any geographical location around the world, with different climates or population densities. In addition, it offers a precise way to verify the real impact of UHI mitigation strategies and concentrate climate change mitigation efforts.
... In the town square and courtyards, studies have typically been conducted in hot-climate regions (Chatzidimitriou and Yannas, 2016). Such climate studies are usually designed for the urban heat island, and in fact, conducted in cold cities (Wang et al., 2015;Yilmaz et al., 2007;Zhang et al., 2018;Mutlu et al., 2018). ...
... The net radiation absorbed by surface materials is the difference between received solar radiation and the outgoing radiation. The energy-balancing equation (Wang et al., 2015(Wang et al., , 2016. for each surface material is given by Q sw;net þ Q lw;netðToÞ À G ðToÞ À H ðToÞ ÀLE ðTo;qoÞ ¼ 0 ...
... The changes in the microclimate may affect the agricultural growth. Understanding the behavior of the complex ecosystem, monitor only the climatic conditions and displays the nearby location of shadow is done in the existing system (Used in smart city environment).Only the Urban Heat Island(UHI) effect [15] is monitored. The drawback of the existing system is, the usage of these details in not up to the greater extend. ...
A proficient microclimate and assisted sustainable agriculture is done using data analytics. The climatic conditions of different places vary with respect to the environment. This is called as microclimatic condition. The changes in the microclimate may affect the agricultural growth. Understanding the behavior of the complex ecosystem, monitor only the climatic conditions and displays the nearby location of shadow is done in the existing system (Used in smart city environment).Only the Urban Heat Island(UHI) effect[15] is monitored. The drawback of the existing system is, the usage of these details in not up to the greater extend. The goal of the proposed system is to provide solution to improve the growth of agriculture when there is a microclimatic change. The project in new methodology is to implement proficient microclimate analysis, to display type of crop and level of irrigation. The climatic conditions of locations such as, Coimbatore, Madurai are collected from Tamil Nadu Agricultural University (TNAU). The collected dataset is processed in RStudio using Boruta algorithm and fuzzy rule based system to address the above challenges. The proposed system helps to improve the agricultural growth of the nation. The final system displays the type of crop to be planted and level of irrigation to be provided to improve the crop plantation and will be disseminated to farmers via website.
... In cold climate regions, the episodes of extreme heat waves are becoming more common in recent years [26,35,40] . For instance, the average temperature in the Greater Toronto Area (GTA) in Ontario has increased continuously since the late 1800s, and the days with air temperatures above 30 °C have already doubled and expected to double again by the end of the 21st century [41,42] . Toronto Public Health determined that heat-related mortality already averaged at 120 deaths per year, with predictions to double by 2050 and triple by 2080 [43] . ...
In this paper, the numerical Weather Research and Forecasting (WRF) model is coupled with a Building Effect Parameterization (BEP) and Building Energy Model (BEM) to investigate the effects on the urban microclimate and building energy demand of increasing the albedo of urban surfaces. For the scope of this study, while the WRP performs real-data applications numerical weather prediction, the BEP serves to predict the heat and moisture fluxes from the urban canopies to the atmosphere and the BEM simulates the effects of anthropogenic heat emissions. As such the overall simulations are capable of taking into account the several factors that influence the urban microclimate and couple their mutual interactions. Outdoor microclimate results for the air temperature and wind speed are compared against measurements in Toronto, ON, during the 2018 heatwave period. The validation confirms the reliability of the WRF model and the selected approach. Then, in order to assess possible urban heat island mitigation strategies, the albedos of roofs, walls, and ground surfaces are increased from 0.2 to 0.65, 0.60, and 0.45, respectively. Results show that the maximum decrease in air temperature through these higher albedo values is nearly 2 °C at noon with a slight increase in wind speed. Moreover, the daily averaged decrease in the urban surface temperature and in the absolute humidity is 3.3 °C and 0.6 g/kg, respectively. Increasing the surface albedo would reduce the solar radiation balance at noon by almost 30 W/m 2. Finally, the combined effect of decreased solar heat gains by urban surfaces and decreased air temperature would reduce the cooling energy demand by almost 10%.
... In cold climate regions, the episodes of extreme heat waves are becoming more common in recent years [60,9,10] . For instance, the average temperature in the Greater Toronto Area (GTA) in Ontario has increased continuously since the late 1800s, and the days with air temperatures above 30 °C have already doubled and expected to double again by the end of the 21st century [20,64] . Toronto Public Health determined that heat-related mortality already averaged at 120 deaths per year, with predictions to double by 2050 and triple by 2080 [42] . ...
In this paper, the numerical Weather Research and Forecasting (WRF) model is coupled with a Building Effect Parameterization (BEP) and Building Energy Model (BEM) to investigate the effects on the urban microclimate and building energy demand of increasing the albedo of urban surfaces. For the scope of this study, while the WRP performs real-data applications numerical weather prediction, the BEP serves to predict the heat and moisture fluxes from the urban canopies to the atmosphere and the BEM simulates the effects of anthropogenic heat emissions. As such the overall simulations are capable of taking into account the several factors that influence the urban microclimate and couple their mutual interactions. Outdoor microclimate results for the air temperature and wind speed are compared against measurements in Toronto, ON, during the 2018 heatwave period. The validation confirms the reliability of the WRF model and the selected approach. Then, in order to assess possible urban heat island mitigation strategies, the albedos of roofs, walls, and ground surfaces are increased from 0.2 to 0.65, 0.60, and 0.45, respectively. Results show that the maximum decrease in air temperature through these higher albedo values is nearly 2 °C at noon with a slight increase in wind speed. Moreover, the daily averaged decrease in the urban surface temperature and in the absolute humidity is 3.3 °C and 0.6 g/kg, respectively. Increasing the surface albedo would reduce the solar radiation balance at noon by almost 30 W/m². Finally, the combined effect of decreased solar heat gains by urban surfaces and decreased air temperature would reduce the cooling energy demand by almost 10%.
... Hence, the peak electricity demands need to be supplied by the coal-burning power plants and fossil fuel combustions where consequently increases GHG emissions. Therefore, the necessity to mitigate the UHI effects is crucial in the GTA, where 17% of Canadian citizens (with a population of more than 6-million people) live ( Wang et al., 2015). The Ontario Ministry of Infrastructure (2012) announced that Toronto would house 2.4 million more people within two decades. ...
Increasing surface reflectivity decreases the skin and air temperature, which potentially reduces cooling energy demands. The state of the art online numerical Weather Research and Forecasting model (WRF) is used to investigate the effect of increasing albedo in Toronto, Ontario, during the 2018 heat wave period (July 2 nd through July 5 th) on urban climate and building energy consumption. The study couples the WRF with a multi-layer of the Urban Canopy Model (ML-UCM) and Building Energy Model (BEM). The ML-UCM is a part of the land-surface parameterization to predict the heat and moisture fluxes from canopies to atmosphere. The BEM is coupled with Building Effect Parameterization to predict the energy consumption of buildings. BEM simulates the effect of heat generation from buildings on urban climate. The reflectivity of roofs, walls and roads are increased from 0.2 to 0.65, 0.60 and 0.45, respectively. Albedo enhancement leads to a decrease in air temperature by around 1 o C and an increase in wind speed which induce a reduction in skin temperature. The combined effect of decreased solar heat gain by buildings and decreased air temperature reduced the energy consumption of HVAC systems by 3-5%, confirming the positive effect of increasing the albedo on urban climate.
... As far as pavement engineering concerns, it is worth highlighting that the thermal characteristics of the materials affected by solar radiations (pavement included) determine reflected, adsorbed and stored energies (Bonan, 2002). Thus, early studies towards the use of thermally optimised solutions for paving (clear or coloured materials, porous surfaces, etc.) can be found in literature (Coseo & Larsen, 2015;Duarte & Ferreira, 2016;Higashiyama, Sano, Nakanishi, Takahashi, & Tsukuma, 2016;Wang, Berardi, & Akbari, 2015). ...
The issues related to the global warming are increasingly becoming of crucial importance for governments and scientific communities, which are trying to develop policies and solutions to slow down this problem in order to limit the related negative effects on environment, human health and economy. The Urban Heat Island (UHI) phenomenon, i.e. the increasing of temperatures within cities with respect to the neighbouring rural spaces, is one of the main aspects related to such a global warming. In this regard, cool road pavements can be really considered as a valuable technological solution to mitigate such a phenomenon. Given this background, the present paper illustrates a comprehensive experimental investigation principally aimed at providing a specific overview of the main thermal behaviour of selected clear and coloured mixtures for pavement surface courses as mitigation strategy for the UHI phenomenon. To this aim, specific indoor (laboratory) and outdoor monitoring were carried out on samples subjected to artificial radiations and sun exposure, respectively. Basic chromatic characteristics and mechanical properties of such materials were also investigated to evaluate prospective correlations with the thermal response as well as real field applicability. Clear mixtures were prepared using “traditional” limestone or “unusual” white marble aggregates bound with a synthetic transparent resin whereas the coloured mixtures were obtained by adding oxide pigments (red or yellow) to a plain bituminous blend. A traditional reference “black” bituminous mixture was also studied for comparison purposes. The experimental findings mainly showed that an optimisation of the thermal response of pavement surface can be achieved leading to remarkable temperature reductions also interesting the surrounding environment, in particular when a transparent binder is used. However, some issues related to the mechanical properties of clear mixes should be addressed since they could limit the real applicability of such materials.
... The maximum Ta differences attributed to the current trees and three designed GIs were up to 2.2, 1.0, 0.4 and 2.4 C, respectively. This result agrees with studies carried out by Wang et al. (2015c) and Yilmaz et al. (2018) in temperate regions, which showed an increase in temperature during winter owing to the presence of the vegetation. Most likely, GIs prevent the heat transfer and reduce the heat exchange between areas inside and outside the canopy in the winter (Akbari, 2002;Wang et al., 2014). ...
Urban green infrastructures (GIs) are proved to effectively mitigate urban warming associated with urbanization, and beneficial to the thermal comfort and energy consumption. Quantifying the impacts of urbanization on microclimate and delineating possible urban GIs strategies to maximize their thermal benefits and energy saving potential are thus of importance. This study examined the impacts of the urban growth in Kwai Chung (a fast-developing urban area in Shenzhen, China) on the local microclimate and thermal comfort by conducting the field measurements inside and outside this area. The contribution of urban warming to the daytime mean Ta was up to 4.9 °C in the warm period, which profoundly exacerbated the heat stress. Using a validated ENVI-met model, numerical simulations were conducted to evaluate the thermal benefits and energy saving potentials of the current trees (mainly located in an urban park) and three designed urban GIs (greenway, green roof and grove) in a high-density residential neighborhood. The results revealed that urban park is capable of regulating the hot and cold environment in adjacent urban zones, resulting in improvements of thermal comfort and 3D energy savings of 24.7 and 40.0 kW per day, respectively in the warm and cool periods. Among the designed urban GIs, greenway manifested the best performance on microclimate regulation and energy saving. This research helps the decision-makers and urban planners to delineate the possible urban GIs strategies to optimize the environmental benefit for achieving ‘smart’ urban growth.
... Similar studies done by Susca, Gaffin, & ity, found an average of 2°C difference of temperature between the maximum and minimum vegetated areas. A maximum 0.8°C reduction of air temperature and mean radiant temperature if urban greening is increased at 10% (Wang Y, Berardi U, Akbari H., 2015). ...
Climate change is a threat to the world. Problems resulting from climate change such as global warming, floods, environmental pollution, high carbon dioxide emissions, and loss of biodiversity may be solved by the implementation of green roofs. Green roof benefits the environment, economy, aesthetics, and recreation and are proven effective through studies conducted from around the world. This paper reviews the existing literature on green roof benefits and performance and specifically focuses on their potential to address climate change issues. A review of significant literature on green roof performance and benefits is the method of this study. From the review, it is proven that green roofs have the potential to reduce problems related to climate change. The depth of a green roof substrate is a key factor that can optimize potential benefits. Thus, intensive types of green roofs provide significant contribution towards reducing storm water runoff; mitigate the urban heat island effect and pollution; increased biodiversity; and carbon sequestration. Local research is highly encouraged in mitigating climate change because the optimal performance of green roofs is subject to local climate and conditions.
... This study proposed a design methodology for residential building layouts that is optimized in terms of the daylight environment with regards to street-oriented block housing, and examined a mass planning methodology based on environmental performance by applying a methodology for wind path planning [19][20][21][22]. In order for a household unit to receive two consecutive hours of daylight through the living room window on the winter solstice, the minimum distance between adjacent buildings at different azimuth angles should be secured, and masses should be configured to prevent daylight infringement due to self-shadows resulting from daylight interference between residential buildings. ...
This study presents a design methodology for street-oriented block housing, as a model for gradual small-scale block-unit development, that can secure two hours of continuous access to daylight on the winter solstice at azimuth angles of 0° and 60° in Seoul, South Korea, and, in addition, developed a methodology for wind path planning for existing types of developed housing. The results of this study have confirmed the feasibility of a housing design that can secure two hours of continuous access to daylight along with no less than 200 percent of development density, achieved through the elimination of self-shadows by using distances between residential buildings and shadow characteristics according to azimuth angles. In addition, the study identified an air flow stagnation section by assessing the air flow of the exterior space of street-oriented block housing in consideration of day-lit environments, and examined a planning model that can enhance natural ventilation potential by activating the air flow of the exterior space. Wind path planning was conducted for 24 alternatives that were produced based on the developed design methodology, and the wind velocity ratio of street-oriented block housing ranged from 0.34 to 0.59. In terms of disadvantages of street-oriented block housing in securing wind paths, this study confirmed that air flow could be strengthened by adjusting the form of the lower-part opening, which is open in the direction of incoming wind, designing a staggered mass layout in high-rise masses, and combining building floor heights. The above findings of this study suggest that a performance-based approach is necessary for the improvement of environmental performance in street-oriented block housing, in consideration of azimuth angles and the prevailing wind direction from the initial phase of planning.
... ay after day the cities growth and became bigger and bigger and the ambient air temperatures (T a ) inside the urban cores are expected to be higher than that in their surrounding countryside, creating urban heat island (UHI) phenomenon [1][2][3][4]. The bad effect of the urban heat island (UHI) phenomenon, particularly on energy use, human health and air quality as well as its significant effect on human comfort, many researchers are focusing on the possible strategies for mitigating UHI and many of them are interested to investigate at the scale of neighbours [4][5][6][7]. There are a number of mitigation strategies. ...
With the growth of cities, the ambient air temperatures (Ta) inside the urban areas are expected to be higher compared to the surrounding rural areas, creating urban heat island (UHI) phenomenon. The city of Baghdad is an example of a hot dry climate cities and during summer, the UHI intensity is significantly affected by the extreme direct solar radiation and leads to outdoor thermal discomfort. Also it causes an increase in energy consumption and air pollution. This research work focuses on the effect of urban geometry and green area in the formation of heat island through a study of two different fabrics of residential neighbourhoods. The height to width ratio (H/W) and vegetation are adopted while the materials of buildings were unified in all study cases. Three-dimensional numerical software Envi-met 4.1 was utilized to analyze and assess the studied parameters including: ambient air temperature (Ta), street surface temperature (Ts) and mean radiant temperature (Tmrt). This study has given a better understanding of the role of urban geometry and green area on forming the UHI that influence on the microclimatic conditions in hot dry climate of the city of Baghdad. So that helped to generate guidelines of urban design and planning practices for a better thermal performance in hot and dry cities.
... The net radiation absorbed by surface materials is the difference between received solar radiation and the outgoing radiation. The energy-balancing equation (Wang et al., 2015(Wang et al., , 2016. for each surface material is given by Q sw;net þ Q lw;netðToÞ À G ðToÞ À H ðToÞ ÀLE ðTo;qoÞ ¼ 0 ...
Implication:
An attempt has made to study the diurnal variation of secondary pollution levels in different study regions. This paper is focusing mainly on the UHI intensity variations with respect to percentage of land use pattern change in Chennai city, India. Simulated the area based land use pattern on local mixing height variations. The relationship between UHI intensity and mixing height variations on local air quality.
... Place Adopted mitigation strategy Belshe, Kaloush, Golden and Mamlouk (2008) Phoenix; USA surface albedo Berardi (2016) Toronto; Canada green roof Brontowiyono, Lupiyanto, Wijaya, and Hamidin (2011) Indonesia green open space Colombert, Diab, Salagnac and Morand (2011) Paris; France surface albedo, geometric aspect Coseo and Larsen (2015) Chicago; Illinois cool pavement Costanzo, Evola, & Marletta, 2016 Catania; Italy green roof, cool roof Declet- Barreto, Brazel, Martin, Chow and Harlan (2013) Phoenix; Arizona vegetation Doick, Peace and Hutchings (2014) London; UK trees, greenspace Ellis et al. (2015) Knoxville; Tennessee trees, land use Elsayed (2012) Kuala Lumpur; Malaysia land management, plant cover Emmanuel and Fernando (2007) Colombo; Sri Lanka albedo enhancement, urban greening Emmanuel, Rosenlund and Johansson, (2007) Colombo; Sri Lanka and Phoenix; USA surface thermal properties, green cover Giridharan and Kolokotroni (2009) London; UK surface albedo, green density Gober et al. (2010) Phoenix; USA water Guindon and Nirupama (2015) Montreal Touchaei and Akbari (2013) Montreal; Canada roof albedo Trihamdani, Lee, Kubota and Phuong (2015) Hanoi; Vietnam green spaces Virk et al. (2014) London; UK cool roofs, green roofs Wang, Xue, Lin and Lablache (2014) Toronto; Canada cool surfaces, vegetation Toronto; Canada albedo, vegetation Xiamen; China shrubs-planted roof Wang, Berardi and Akbari (2015) Montreal; Canada surface albedo, vegetation Zhou and Shepherd (2010) Atlanta; Georgia surface albedo, vegetation greening and permeable soils. Other researches focused their attention on the morphological features (Ghaffarianhoseini, Berardi, & Ghaffarianhoseini, 2015;Ketterer & Matzarakis, 2014;Middel, Häb, Brazel, Martin, & Guhathakurta, 2014;Perini & Magliocco, 2014;Yahia & Johansson, 2014) and some interesting results were obtained by Ketterer and Matzarakis (Ketterer & Matzarakis, 2014). ...
... Many urban mitigation and adaptation strategies are proposed to cope with the summer UHI. Some suggest more resilient urban planning [7,8], while others propose vegetated systems and green roofs [9][10][11][12]. Still more recommend making use of reflective and cool surfaces [13][14][15][16][17]. ...
The combined effects of heat events and poor air quality conditions can severely affect population health. A novel correlational method was developed to assess the impact of the short-term variations of environmental variables (air pollutants and ambient conditions) on community health responses (mortalities and emergency department visits). A multi-dimensional clustering approach was proposed by combining hierarchical and k-means clustering to promote flexibility and robustness to improve the correlation procedure. The study focused on the health records of the elderly population and people diagnosed with cardiorespiratory causes. The study investigated multiple health records on different levels of investigation: total, elderly, cause-based, and elderly cause-based records. The developed method was validated by investigating the short-term impact of ambient air temperature, relative humidity, ground-level ozone, and fine particulate matter on the health records during hot and warm seasons in the municipalities of Mississauga and Brampton, Peel Region, Ontario, Canada for 15 years. The analysis confirmed the association between moderate levels of environmental variables and increased short-term daily total deaths and emergency department visits, while the elderly sector showed higher vulnerability to environmental changes. Furthermore, the association with extreme heat conditions and poor air quality levels was affirmed with cause-based mortalities and emergency visits; the correlation was strongest with elderly cause-based health records. Findings confirm that cardiorespiratory patients, especially elderly people, were at the greatest risk of poor environmental conditions.
Sunrays fall daily on the facades, roofs, pavements and asphalts, causing an increase in surface temperatures and Summer Urban Heat, especially during summer time and in countries of hot climates. This results in an increase in the rate of energy consumption as a result of the presence of reflective materials, such as Cool Coating for asphalt, facades, and roofs, which is manufactured and applied to buildings and on sidewalks to reduce the temperature emissions within the surrounding urban environment. This paper measures the success of using Cool Coating for pavements and asphalt as well as Cool Coating for building facades and roofs in Giza, Egypt. It also draws up a comparison between them to identify which is better, in terms of performance, in reducing air temperatures and their Physiological Equivalent Temperatures (PET), as an indicator of a Human physiological response to the urban heat-island effect in Giza, Egypt. A study is conducted using the ENVI-met computer simulation software, to mimic the microclimate in the urban environment and select the best results. The study concluded that the use of Cool coating for building facades and external surfaces, in Giza Square, exhibited excellent performance in reducing air temperature and PET value, optimizing climatic performance of existing buildings and urban areas, and helping to reduce energy use and impact of the summer urban heat.KeywordsCool coatingENVI-metUrban heat effectUrban heat islandPhysiological equivalent temperatureUrban environment
Human urbanization has a great impact on the surface ecological environment, and few existing studies have explored the impact of urbanization on regional comfort on a long time scale. This study took Chenggong District, Kunming City, Yunnan Province, China, where urbanization was obvious, as the study area, and used the comfort evaluation model to evaluate the annual summer Discomfort Index (DI) in different periods of urbanization. Meanwhile, the impact strength of each factor characterizing human activities (Impervious surface, Gross National Product, and Total Population) on DI changes was analyzed, and the contribution rate of the main factors was quantified. The experimental results show that (1) over the past 20 years, under the background of the rapid economic development of Chenggong District, the annual average DI in summer showed an upward trend. The growth rate after the completion of University Town (2010–2020, Post-UT) was higher than that before the completion of University Town (2001–2005, Pre-UT). University Town was growing much faster than other regions. The monthly average DI changes were similar to the annual average changes. However, due to the movement of students in University Town during the summer vacation, the growth rate of DI in June was significantly higher than that in other months. (2) In terms of spatial changes, DI in the central and northwestern parts of Chenggong District increased significantly from 2001 to 2020. There were differences in the change rate before and after the completion of University Town. The area occupied by significant growth areas in June was much higher than in other months. It is proved that the economic and social development of Chenggong District would impact the regional human comfort, and the construction of University Town has aggravated the intensity of this impact. (3) In the during-UT, affected by the complex changes in land use types, the DI in Chenggong District showed fluctuations in time, but there was no obvious change in space. (4)The correlation and contribution analysis showed that the annual average DI in summer was closely related to human activities, especially the impervious surface had a strong contribution rate of 52.7%. The research shows that the development of new cities would have a strong impact on regional DI changes. And the obtained results will provide theoretical support for rational planning and management in the process of urban development in the future, thereby promoting the sustainable development of the region.
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The cooling effect of green spaces as an ecological solution to mitigate urban climate change is well documented. However, the factors influencing the microclimate in the built environment around forest parks, diurnal variations of their impact and their degree of importance have not been explicitly addressed. We attempted to quantify how much various landscape parameters, including land cover and spatial location, impact the ambient air and surface temperature in the area around Beijing’s Olympic Forest Park. Data were taken along strategically located traverses inside and outside the park. We found: (1) The air temperature during the day was 1.0–3.5 °C lower in the park than in the surrounding area; the surface temperature was 1.7–4.8 °C lower; air humidity in the park increased by 8.7–15.1%; and the human comfort index reduced to 1.8–6.9, all generating a more comfortable thermal environment in the park than in the surrounding area. (2) The distance to the park and the green space ratio of the park’s surrounding area are significant factors for regulating its microclimate. A 1 km increase in distance to the park caused the temperature to increase by 0.83 °C; when the green space ratio increased by 10%, the temperature dropped by 0.16 °C on average. The impact of these two parameters was more obvious in the afternoon than in the middle of the day or in the morning. The green space ratio could be used for designing a more stable thermal environment. (3) Land cover affects surface temperature more than it does air temperature. Our data suggest that an urban plan with an even distribution of green space would provide the greatest thermal comfort.
Air temperature (Ta) of urban areas is increase compare to the surrounding rural areas creating Urban Heat Island (UHI) phenomenon. In hot and dry regions, such as Baghdad, and during the long hot summer periods, the UHI intensity is significantly influenced by the extreme direct solar radiation and lead to increase the energy consumption and air pollution as well as outdoor thermal discomfort.
Many researchers have reported that most of the current patterns existed in Baghdad City did not take into consideration the extreme external microclimate conditions when they were designed. That is greatly affected the thermal discomfort in the outdoor spaces. The residential is the largest use in the city of Baghdad as well as the highest energy consuming. Accordingly, the problem of this study was determined by: "There is a need to investigate the impact of different residential patterns and Microclimate Improvement Strategies on the local and micro climate condition as well as thermal comfort of Baghdad City".
The aim of this study is to investigate the impact of urban patterns in Baghdad City,
which are differ in their geometry and vegetation covered, on the microclimate conditions and human thermal comfort. In addition, the study tries to evaluate the effects of microclimate improvement strategies on micro-climatic conditions and thermal comfort in these patterns at the scale of pedestrian level. Accordingly, Research Hypothesis:
a) Various urban patterns in the city of Baghdad have different influence on the quality of the urban environment and on human thermal comfort. b) Microclimate Improvement Strategies can contribute to improve micro-climatic conditions and thermal comfort in urban patterns.
The present study methodology was depended on two steps: the first one deal with a comprehensive study of the Land Surface Temperature (LST) variations in Baghdad City and it's relation to the land surface covered, urban patterns existed, population densities and land uses. That helped to assess the impact of urban patterns existed on LST and local climate conditions. On the basis of LST result, areas for investigation were selected. Second, the selected areas are investigated on the base of their effect on microclimate conditions and thermal comfort, and how microclimate improvement strategies can effect on these areas at the scale of pedestrian level. Three Microclimate Improvement Strategies were used in this study which were Urban geometry, Vegetation covered and Cool material of surface. Simulation tool Envi-met was used to evaluate and assess the selected study areas and how Microclimate Improvement Strategies effect on them. Typical summer day was selected in this study which was 15/7/2015, this day was represented one of the hottest days in 2015 year. Five parameters were measured in this study which were ambient air temperature (Ta), street surface temperature (Ts), mean radiant temperature (Tmrt), relative humidity (RH) and wind velocity (V). All measurements are taken in pedestrian walkway of each area. The assessment of human thermal comfort in outdoor spaces were conducted according to Predicted Mean Vote (PMV).
This study has provided a better understanding of the role of urban patterns and
microclimate improvement strategies on human thermal comfort and quality of outdoor spaces of Baghdad's residential neighborhoods. So that its helps to generate the guidelines of urban design and planning practices for a better thermal performance in hot and dry cities. Among different microclimate parameters, mean radiant temperature (Tmrt) was found to have a significant effects on human thermal comfort in outdoor spaces.
Todays, most Iraqi cities suffer from extremely hot-dry climate for long periods throughout the year. However, most urban patterns that exist inside these cities are not suitable for this harsh conditions and lead to an increase in the value of the Urban Heat Island (UHI) index. Consequently, this will increase outdoor human thermal discomfort as well as energy consumption and air pollution in cities. This study attempts to evaluate the effect of UHI mitigation strategies on outdoor human thermal comfort in three different common types of urban patterns in the biggest and most populated city in Iraq, Baghdad. Three different mitigation strategies are used here – vegetation, cool materials, and urban geometry – to build 18 different scenarios. Three-dimensional numerical software ENVI-met 4.2 is utilised to analyse and assess the studied parameters. The input data for simulations process are based on two meteorological stations in Baghdad: Iraqi Meteorological Organization & Seismology, and Iraqi Agrometeorological Network. All measurements are taken in a pedestrian walkway. The results of different scenarios are compared based on their effect on human thermal comfort. Outdoor thermal comfort is assessed according to Predicted Mean Vote index, as mentioned in ISO 7730 standard. This study provides a better understanding of the role of UHI mitigation strategies on human thermal comfort in the outdoor spaces of Baghdad's residential neighbourhoods. This can help generate guidelines of urban design and planning practices for better thermal performance in hot and dry cities.
The changing local climate in urban areas has raised concerns for monitoring and mitigating heating effects in built environments worldwide. The analysis of long-term temperature reveals that winter temperature has been increasing more than the summer temperature in the cities of India. Lack of strategic policies for urban heat island (UHI) mitigation in India makes the research in this field quite difficult. Although some studies have addressed the impacts of atmospheric pollution, aerosol optical depth, and greenhouse emissions on UHI, development of approaches to devise scientifically backed strategies and policies on urban areas is still missing. An effort has been made in the research presented int his chapter to suggest some techniques for UHI mitigation and climate resilient adaptation strategies befitting the tropical situation. The effects of vegetation and albedo enhancement on urban canopy environment have been examined through numerical simulation and evaluated in terms of the environmental attributes such as (1) air temperature (Ta), (2) human-weighted mean radiant temperature (MRTh−w), (3) wind speed, and (4) physiological equivalent temperature (PET) considered at a community scale. The effects of existing urban development on urban thermal heterogeneity have been assessed where the simulation results demonstrated the potential of mitigation strategies in ameliorating urban thermal conditions during a typical summer day. The simulation results point toward the strategic and policy-oriented measures need to be taken to mitigate the adverse UHI effects.
Comfortable outdoor environment benefits the health of citizens and reduces energy consumption and pollution. This study discusses different outdoor thermal sensation and comfort evaluation methods in severe cold area. The database was from a year-long outdoor thermal comfort survey conducted in Harbin, China. Thermal sensation evaluation was developed using meteorological parameters and three popular thermal comfort indices including Standard Effective Temperature (SET*), Physiologically Equivalent Temperature (PET) and Universal Thermal Climate Index (UTCI). Thermal comfort prediction was developed by the three thermal comfort indices and acceptability. Original thermal sensation scales of SET* and PET were less applicable to predict thermal sensation vote (TSV). Calibrated scales of the three indices were obtained based on linear regression results and probit analysis. The accuracies of calibrated scales of thermal sensation were all below 33%. The comfortable thermal sensation range in severe cold area varied from “slightly cool” to “hot”. This calibrated range improved accuracies of thermal comfort predicting by around 20%. The unacceptability appropriate to define comfortable range was 9% on the cold thermal sensation side and 26% on the hot side. Adaptation and local exposure also acted on thermal sensation and comfort apart from factors included in thermal comfort indices. Our results provide practical thermal sensation and thermal comfort scales for severe cold area. The discussions indicate the significance of considering adaptation and local exposure for further improving thermal sensation and comfort predicting.
Experiments were conducted to assess the potential impact of cool and/or green roofs to mitigate summertime conditions in two cities of Israel, Jerusalem and Tel Aviv, which differ in elevation, humidity, and housing density. Tel Aviv is located along the coastal plain and characterized by low- and medium-density housing in a humid climate. Jerusalem is in the central mountains (elevation >750 m), and characterized by medium- and high-density housing in a dry climate. The fraction of potential roofs available for reflective cooling and the fraction of green versus impervious surface areas were estimated from “Google Earth.” Both were utilized as input into the Urban Canopy Model (UCM) within the Weather Research and Forecasting model, along with the residential building density. Increasing the albedo (cool roofs) had a larger impact on roof surface radiometric temperatures than covering the roof with irrigated soil and vegetation. Cool roof surface temperature differences were about 20 °C, compared to between 10 and 15 °C for wet soils with vegetation. The impact of varying albedo on 2-m. surface temperatures was about 0.4 °C, and the impact of varying soil moisture 0.1 °C. Increasing the leaf area index from 1.5 to 4.5 had a comparatively small impact on 2 m temperatures. Imposed anthropomorphic heating added about 0.2 °C to 2-m surface temperatures, which was less than values found in other studies conducted with more sophisticated building energy models. The surface temperature and heat index within Tel Aviv were more sensitive to mitigation efforts than those in Jerusalem, but both cities could benefit from mitigation efforts.
Most of the urban heat island (UHI) studies are carried out in densely populated cities but core industrial areas are also potential sites of heat island effect despite having a comparatively lower population. In the present study, heat island assessment has been carried out for Angul-Talcher industrial area (ATIA) which is one of the oldest industrial areas of India and is still undergoing a transformation to accommodate more industries and mining operations. As the major contributors towards influencing local meteorology were expected to be industrial (and mining) activities, the heat island was studied as “industrial heat island” (IHI) rather than urban heat island. Industrial and mining sites were the most frequent nighttime canopy-layer heat island intensity (HIN) hotspots due to anthropogenic heat of associated industrial processes as well as built structures. During the daytime, croplands experienced the most frequent canopy-layer HIN hotspots which could be attributed to low moisture of the soils during the non-farming period of the field campaign. Hourly maximum atmospheric heat island intensities were observed in the range of 7–9 °C. Monthly maximum HINs ranged from 2.97 to 4.04 °C while 3-month mean HINs varied from 1.45 to 2.74 °C. Amongst different land use/land cover classes, the highest mean canopy-layer heat island intensity for the entire 3-month-long duration of field campaign during nighttime was assessed at the mining sites (3-month mean 2.74 °C) followed in decreasing order by the industrial sites (2.52 °C), rural and urban settlements (2.13 °C), and croplands (2.06 °C). Corresponding daytime canopy-layer heat island intensity was highest for the croplands (2.07 °C) followed in decreasing order by the mining sites (1.70 °C), rural and urban settlements (1.68 °C), and industry (1.45 °C).
This study presents an analysis of the effect of height/width proportions of street canyons on microclimatic conditions in the most urbanized part of Lodz. The empirical research covered public spaces located in the so-called Greater City Zone of Lodz, which were included in the revitalization process. In this case, two street canyons were selected, which are used as pedestrian and driving canyons (the so-called woonerfs). At first, the authors determined the average weather conditions prevailing in the warm period of Typical Meteorological Year in the area of city. On their basis, microclimatic parameters prevailing in the areas of selected street canyons were evaluated with the use of computer simulations. The next stage included the determination of aspect ratio (AR) defining the ratio of building height forming the frontage of canyons to the street width. Finally, the relation between the determined coefficient and selected weather parameters was studied.
It is known that changes in urban surface characteristics lead to different urban climates. The surrounding environment directly affects thermal comfort and human behavior. In this respect, for sustainable urban growth, the evaluation of urbanization together with climate change from past to present is also important for planning.
The main aim of the study is to propose a retrospective GIS-based change detection method for the monitoring of urban climate change by using satellite images. Two regions with a diameter of 1 km where there are significant constructional changes in Istanbul were selected as the study areas. The comparisons were made through Landsat thermal images during summer between the years 2007 and 2017. The function of the model proposed in the study was tested by evaluating whether the expected climatic changes could be achieved against the constructional changes that took place in the region. The correlations between the regions that get extremely hot / cold and the constructional change areas were examined by the bivariate method. The results showed that the correlations could reach up to a high level when important changes occurred in the areas.
Natural areas are quickly degraded by opening new settlement and industrial areas in order to meet the increasing demand of the growing population. Concreting, modification of land surfaces, complex urban structures, and depressed urban environments contribute to the formation of an Urban Heat Island (UHI). In this study, the outdoor measurements, meteorological parameters related to the thermal indices such as humidity, temperature, wind velocity, and direction for 24 h measurements, were evaluated. The ENVI-met micro-scale model was performed for evaluating alternative scenarios for winter and summer on thermal comfort for better urban environments. Meteorological parameters together with vegetation characteristics were analyzed for making possible scenarios in botanical garden, auto industrial area, city center, and rural open area. The average of the vegetated simulations of the botanical garden was about 2.2 °C cooler than this of the mean of current situation in the city center. Based upon the average of all stations, it was determined that the temperature increased 1.4 °C with the simulation of both wooded areas in winter. However, the mean temperature of all stations with coniferous plants was 1.2 °C cooler, in summer. It was concluded that deciduous plants in city center produced more positive results than coniferous plants in winter. In general, it can be said that afforestation in cold climatic regions provides great advantages for both summer and winter and positively affects outdoor thermal comfort. However, it needs further measurement and further research in this regard.
El uso extensivo de grandes superficies urbanizadas en Bogotá ha causado el incremento de islas de calor en la ciudad, fenómeno que va en detrimento de la calidad del hábitat urbano. En dicha medida, el propósito de esta investigación fue describir los conceptos de resiliencia, cambio climático y vulnerabilidad aplicados en Bogotá, puesto que una alternativa a esta problemática es desarrollar el concepto de territorio resiliente dentro de los procesos de construcción de la ciudad. Un territorio resiliente se define como la superficie que contiene múltiples espacios que relacionan diferentes actores para caracterizar un área urbana. El resultado de esta investigación fue un piloto de simulación
estocástica simple, el cual generó una metodología de evaluación con el propósito de identificar el comportamiento de un Territorio Resiliente y Eficiente (TRE), capaz de acomodarse a las nuevas situaciones ambientales.
The aim of this work is to study urban heat island (UHI) in Metropolitan Area of Rio de Janeiro (MARJ) based on the analysis of land-surface temperature (LST) and land-use patterns retrieved from Landsat-5/Thematic Mapper (TM), Landsat-7/Enhanced Thematic Mapper Plus (ETM+) and Landsat-8/Operational Land Imager (OLI) and Thermal Infrared Sensors (TIRS) data covering a 32-year period between 1984 and 2015. LST temporal evolution is assessed by comparing the average LST composites for 1984–1999 and 2000–2015 where the parametric Student t-test was conducted at 5% significance level to map the pixels where LST for the more recent period is statistically significantly greater than the previous one. The non-parametric Mann-Whitney-Wilcoxon rank sum test has also confirmed at the same 5% significance level that the more recent period (2000–2015) has higher LST values. UHI intensity between “urban” and “rural/urban low density” (“vegetation”) areas for 1984–1999 and 2000–2015 was established and confirmed by both parametric and non-parametric tests at 1% significance level as 3.3 °C (5.1 °C) and 4.4 °C (7.1 °C), respectively. LST has statistically significantly (p-value < 0.01) increased over time in two of three land cover classes (“urban” and “urban low density”), respectively by 1.9 °C and 0.9 °C, except in “vegetation” class. A spatial analysis was also performed to identify the urban pixels within MARJ where UHI is more intense by subtracting the LST of these pixels from the LST mean value of “vegetation” land-use class.
Urban microclimate studies are gaining popularity due to rapid urbanization. Many studies documented that urban microclimate can affect building energy performance, human morbidity and mortality and thermal comfort. Historically, urban microclimate studies were conducted with observational methods such as field measurements. In the last decades, with the advances in computational resources, numerical simulation approaches have become increasingly popular. Nowadays, especially simulations with Computational Fluid Dynamics (CFD) is frequently used to assess urban microclimate. CFD can resolve the transfer of heat and mass and their interaction with individual obstacles such as buildings. Considering the rapid increase in CFD studies of urban microclimate, this paper provides a review of research reported in journal publications on this topic till the end of 2015. The studies are categorized based on the following characteristics: morphology of the urban area (generic versus real) and methodology (with or without validation study). In addition, the studies are categorized by specifying the considered urban settings/locations, simulation equations and models, target parameters and keywords. This review documents the increasing popularity of the research area over the years. Based on the data obtained concerning the urban location, target parameters and keywords, the historical development of the studies is discussed and future perspectives are provided. According to the results, early CFD microclimate studies were conducted for model development and later studies considered CFD approach as a predictive methodology. Later, with the established simulation setups, research efforts shifted to case studies. Recently, an increasing amount of studies focus on urban scale adaptation measures. The review hints a possible change in this trend as the results from CFD simulations can be linked up with different aspects (e.g. economy) and with different scales (e.g. buildings), and thus, CFD can play an important role in transferring urban climate knowledge into engineering and design practice.
In this paper, the interactive action between minimally invasive surgical suture needle and soft tissue was investigated under different insertion velocities, needle geometries, insertion angles and tissue characteristics to simulate the real surgical suture needle-tissue operation conditions. Experimental results demonstrated that the process of insertion was divided into two phases: no break phase and break phase. The puncture force generated at the mutation point where the tissue surface was breached. The puncture force and time for the first puncture significantly decreased with the increasing insertion velocity. The needle with triangle cross-section tip and larger size showed higher puncture force than that with round cross-section and smaller one. The penetration force reduced evidently with the advancing insertion angle, and it reached the lowest value when the angle is 90°. Moreover, an empirical single-parameter model of third-degree polynomial could predict the stiffness when a suture needle inserted into a complex soft tissue and showed a good fit to the experiment data. The results would provide reliable and significant mechanical database for the design of force feedback system in the surgical suture, either in endoscopic surgery or robotic suturing.
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.
Modern supercomputers allow realising multi-scale systems for assessment and forecasting of urban meteorology, air pollution and emergency preparedness and considering nesting with obstacle-resolved models. A multi-scale modelling system with downscaling from regional to city-scale with the Environment – HIgh Resolution Limited Area Model (Enviro-HIRLAM) and to micro-scale with the obstacle-resolved Micro-scale Model for Urban Environment (M2UE) is suggested and demonstrated. The M2UE validation results versus the Mock Urban Setting Trial (MUST) experiment indicate satisfactory quality of the model. Necessary conditions for the choice of nested models, building descriptions, areas and resolutions of nested models are analysed. Two-way nesting (up- and down-scaling), when scale effects both directions (from the meso-scale on the micro-scale and from the micro-scale on the meso-scale), is also discussed.
ABSTRACT
This book (Vol. 2) describes the 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
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.
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.
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.
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.
Building integrated photovoltaics (BIPV) has potential of becoming the mainstream of renewable energy in the urban environment. BIPV has significant influence on the thermal performance of building envelope and changes radiation energy balance by adding or replacing conventional building elements in urban areas. PTEBU model was developed to evaluate the effect of photovoltaic (PV) system on the microclimate of urban canopy layer. PTEBU model consists of four sub-models: PV thermal model, PV electrical performance model, building energy consumption model, and urban canyon energy budget model. PTEBU model is forced with temperature, wind speed, and solar radiation above the roof level and incorporates detailed data of PV system and urban canyon in Tianjin, China. The simulation results show that PV roof and PV façade with ventilated air gap significantly change the building surface temperature and sensible heat flux density, but the air temperature of urban canyon with PV module varies little compared with the urban canyon of no PV. The PV module also changes the magnitude and pattern of diurnal variation of the storage heat flux and the net radiation for the urban canyon with PV increase slightly. The increase in the PV conversion efficiency not only improves the PV power output, but also reduces the urban canyon air temperature.
ENVI-met website: www
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The influences of local environmental design on microclimate -development of a prognostic numerical model ENVI-met for the simulation of Wind, temperature and humidity distribution in urban structures
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The warm earth: thermal remote sensing. The remote sensing tutorial. Section 9
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Mechanisms of energy transfer. Frost protection: fundamentals, practice and economics. Chapter 3
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