Top PDF Impact of Street Canyon Geometry on Outdoor Thermal Comfort and Weather Parameters in Pécs

Impact of Street Canyon Geometry on Outdoor Thermal Comfort and Weather Parameters in Pécs

Impact of Street Canyon Geometry on Outdoor Thermal Comfort and Weather Parameters in Pécs

H-7624 Pécs, Hungary, e-mail: balint.baranyai@mik.pte.hu Received 26 December 2018; accepted 25 March 2019 Abstract: As streets cover almost twenty-five percentages of the urban open spaces, designing streets is a vital issue in creating thermal comfort for urban environmental design. The geometry of the street (height/width ratio) as well as orientation directly influences the airspeed, solar access in urban canyon and as a result thermal comfort at the pedestrian level. This study examined the street geometry case study’s scenarios with different street geometries and investigates its effects on outdoor thermal comfort as well as the weather parameters. However, according to the matrix assessment conducted by the author, the vast street canyons (height/width=0.65 m/14.5 m with an orientation parallel to the prevailing wind direction achieved the best results. Nevertheless, the aim of this paper is to investigate the impact of street canyon geometry on outdoor thermal comfort and its parameters in the summertime using numerical modeling.
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Impact of thermal behaviour on outdoor human thermal comfort in tropical climate

Impact of thermal behaviour on outdoor human thermal comfort in tropical climate

Due to the increasing rate of urbanisation and population, the consequences resulting from heat impacts should be vital in order to obtain sustainable living. Climate change on outdoor thermal environment and UHI dominantly effect human health and well-being in a city. The increment in outdoor air temperatures also creates economic consequence, where UHI has clearly exemplified the environmental and economic impacts associated with a rise of ambient temperature. Apart from that, climate effects are negatively impacted by the UHI phenomenon, especially for people working outdoors. The outdoor environment is the most extreme and critical condition in investigating human thermal comfort as it is exposed to the "double sun" phenomena, exposure from both direct sunlight and heat reflecting off the surrounding buildings. These issues can lead to social impacts if there is still lack of awareness and attention given to the thermal condition. The current study focused on the determination of thermal comfort in selected areas, with several urban environmental parameters, i.e. street geometry, orientation, surface albedo and vegetation, and concentrated on using conventional methods for accessing heat stress. However, a knowledge gap still exists, which can be related to the impacts of thermal behaviour on outdoor human thermal comfort and heat stress in tropical climate, in terms of the effect of the built environment, land use and artificial construction materials. Little research can be found on the relationship between the impact of urban surface thermal behaviour and outdoor thermal comfort in Johor Bahru a city in Malaysia.
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A Model-Based Approach to Measuring the Effect of Shading on Outdoor Thermal Comfort

A Model-Based Approach to Measuring the Effect of Shading on Outdoor Thermal Comfort

system as shown in Fig. 1. The symmetric urban system comprises sixteen square blocks, although only the inner 9 blocks are considered for the mobility decisions. Each block measures m × n (m), and is occupied by a single building. The implication of this assumption is that the distance between buildings in each block is negligible. We consider building height and density as the design parameters of urban built form. For simplicity, it is assumed that all buildings have the same height h (m). Since building size is fixed for the case study presented in the next section, the difference in building density is a product of the distances between buildings. It is assumed that the distance between buildings equals the sum of the street and sidewalk width, thus making the entire block made up by a building with no front or dead spaces. Furthermore, we assume that population is evenly distributed in the specified urban system. The above assumptions allow us to examine and compare the impact of geometry alone, foregoing the complexities found in real urban textures. The attractiveness of these generic forms lie mainly in their simple and repeatable characteristics, which allows a more systematic comparative analysis on the effects of different design parameters on mobility patterns [6].
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Effect of the Shadings Pattern and Greenery Strategies on the Outdoor Thermal Comfort

Effect of the Shadings Pattern and Greenery Strategies on the Outdoor Thermal Comfort

Fig. 1. Location of Iraq and the neighbouring countries . Regarding the investigation study conducted in Iran (Tehran city) on the strategies to reduce the impact of Urban Heat Island on the human health [2], the results showed that the amount of vegetation placed on a building and its position (roofs, walls or both) is a more dominant factor than the orientation of the urban canyon. The canyon geometry with green roofs and walls that had a low thermal impact could play a more important role than the street orientation. Also, the study revealed that the heat sensation zones “hot” and “warm” are not achieved when urban roofs and walls are covered with vegetation, leading to more pleasant and comfort environments for the city residents. An investigation study was conducted of the warm core of Urban Heat Island in the highland zone of Muscat, Oman [3]. The valley is surrounded by mountains formed of dark colored rocks that can absorb the short wave radiation and contribute to the existence of the warmth in the core of the urban area. The study emphasized the importance of the nature of rural baseline when assessing the urban effect on an urban area climate. A study was conducted in Bahrain City [4] to analyze the impact of the urbanization on the thermal behaviour of newly built environments. The results revealed that the recent process of the urbanization leads to an increase in the urban temperature by 2-5 ℃. The increase in temperature is enhanced by the urban activity such as on- going construction processes, shrinkage of green areas and the sea reclamation. Several studies indicate how the green effects have a crucial role in the process of sustainable cooling of the urban planning and in saving energy and
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Future context for thermal comfort: Impact of a changing climate on energy demand and human thermal comfort

Future context for thermal comfort: Impact of a changing climate on energy demand and human thermal comfort

Additionally, human thermal comfort parameters include other complex variables like mean radiant temperature (MRT) and air velocity, which were not considered in this preliminary study. ASHRAE Standard 55-2010 gives reference for adaptive human thermal comfort related to increased air velocity as present with natural ventilation, adaptive clothing behavior, ceiling fans, shading and other design related practices, which could be retrofitted into the studies typical house, but are currently not present and are very often not practiced in many residences in the Midwest of the United States. None of these adaptive strategies were included in the presented calculations in order to keep the numbers consistent and to highlight the fact, that a changing climate would significantly increase energy demand or jeopardize human comfort.
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A review of researches about human thermal comfort in semi-outdoor spaces

A review of researches about human thermal comfort in semi-outdoor spaces

et al. (2008), three categorizations is introduced. The first type is located inside the buildings such as entry atrium. The second type is covered spaces which are connected to structure like balcony. The last type is shaded spaces situated in outdoor envi- ronment entirely. Station, covered street and pavil- ions are regarded in this category. Thermal comfort in semi-enclosed spaces is the result of interaction of human subjective factors with four main thermal elements, i.e. air temperature, wind speed, solar ra- diation and humidity. There are several researches on assessment human thermal comfort in outdoor areas(e.g. Cheng et al., 2007; Ali-Toudert and May- er, 2006; Nikolopoulou and Lykoudis, 2006; Tse- liou et al., 2010),but the number of studies which entirely focused on analyzing human thermal com- fort in semi-opened spaces is few. However, the at- tention of scientists about investigation of thermal comfort conditions of semi-outdoor spaces has
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Prioritizing Underserved Communities for Thermal Comfort Street Retrofit in Eugene, OR

Prioritizing Underserved Communities for Thermal Comfort Street Retrofit in Eugene, OR

The project first focuses on prioritizing vulnerable communities in Eugene through spatial analysis using American Community Survey (ACS) socio-economic data and the UHI map. Using expert surveys and Garret’s Ranking Technique, 25 block groups were identified and prioritized for thermal comfort street implementation. After considering the locations of vulnerable communities, I propose a city-wide thermal comfort street network along with specific street design recommendations of four selected block groups based on the urban form types and demo- graphic characteristics. This proposal could help the City of Eugene to efficiently allocate its resources for climate change adaptation through prioritizing vulnerable communities and implementing effective design interventions.
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On the impact of the wind speed on the outdoor human comfort: a sensitivity analysis

On the impact of the wind speed on the outdoor human comfort: a sensitivity analysis

486 6 Silvia Coccolo et al. / Energy Procedia 00 (2017) 000–000 S. Coccolo et al. / Energy Procedia 122 (2017) 481–486 4. Conclusion The work presented in this paper is a first attempt to quantify the impact of a wind speed profile in an effort to analyze outdoor human comfort at the district scale. The outdoor human comfort is quantified by PET, COMFA* and PMV, using the software CitySim Pro and RayMan. Firstly, the human thermal sensation is quantified using weather data as provided by Meteonorm. Then, the wind profile is modified, as recorded by the on-site weather station MoTUS, located in the EPFL campus, during the month of March 2017. The impact of the wind speed is then calculated by each thermal model, showing the great impact of a realistic wind profile in thermal comfort analyses. Effectively, pedestrian p1 varies its average thermal sensation from 9.14°C to 5.3°C, consequently feeling “cool” or “cold”, respectively. The maximum difference between the recorded wind speeds appears between 1.5 m and 9.5 m, which corresponds to the average building height of the campus. The difference is dependent on the wind speed (light breeze or strong wind), as well as on the nebulosity of the sky.
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LES of flow in the street canyon

LES of flow in the street canyon

Abstract: Results of computer simulation of flow over a series of street canyons are presented in this paper. The setup is adapted from an experimental study by [4] with two different shapes of buildings. The problem is simulated by an LES model CLMM (Charles University Large Eddy Microscale Model) and results are analysed using proper orthogonal decomposition and spectral analysis. The results in the channel (layout from the experiment) are compared with results with a free top boundary.

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Enhancement of Outdoor Thermal Comfort through Adoption of Environmental Design Strategies

Enhancement of Outdoor Thermal Comfort through Adoption of Environmental Design Strategies

Abstract The impact of rapid growth of urbanization on the pattern of pedestrian movement as well as people’s stop time in outdoor spaces is inconceivable .Since conditions that are created by physical characteristics of open spaces that exposed to direct sun, have a significant effect on pedestrian’s behavior, in this research, the influence of micro scale urban design on pedestrian comfort is investigated in different time of day in Tehran as a hot and dry city. In this regard, the Vali-ASR Avenue in Tehran has been studied by simulation method in Envi-met software. In this paper we used the Envi-Met software and the ambient site temperature parameter to analyze and compare the energy efficiency of design elements including vegetation density, water features and pavement materials in the morning and high noon time (presence of light). Results show that and presence of sun in high noon is the major reason of high effect of climatic element on thermal comfort and using all landscape design elements at the same time is the most effective way to reduce the overall intensity of temperatures in the linear open spaces.
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Outdoor thermal comfort within five different urban forms in the Netherlands

Outdoor thermal comfort within five different urban forms in the Netherlands

Finally, our recommendation for further research on the courtyard as an optimal urban form is to study the effects of different orientations on insolation and different aspect ratios (length to width and height to width) on the microclimate. Another parameter that plays an important role in the urban microclimate is vegetation. Trees and deciduous trees in particular can protect spaces from direct sun in summer and allow solar radiation in winter. Vegetation also has a low heat capacity. Referring back to the PET which illustrates thermal comfort, it increases in the afternoon. This is because the heat stored during the day is released to the air during the afternoon and evening. More investigations are needed to show whether green areas with a lower heat capacity (over construction materials) can minimise the canyon
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Psychological Adaptation of Outdoor Thermal Comfort in Shaded Green Spaces in Malaysia

Psychological Adaptation of Outdoor Thermal Comfort in Shaded Green Spaces in Malaysia

When designing sustainable green space, addressing outdoor thermal comfort and heat stress have become more a prevalent focus. Therefore, the physiological and psychological impact should have been taken into account when designing green spaces. Previous studies described thermal comfort as a fundamental parameter, as well as how heat stress/thermal discomfort affects these outdoor activities (Knez et al., 2009; Nikolopoulou & Steemers, 2003; Vanos et al., 2010). These studies explained the consequences, implication and outcomes of how heat stress affected human life. Givoni et al.(2003)mentioned while staying outdoors, people should have various unlimited condition like the sun and shade, changes in wind speed, and so on. Moreover, some studies stated the need of shades as an important element for outdoor spaces (Akbari et al., 2001; Hwang et al., 2010). Comparisons between demography were also studied; between the age group(Kenny et al., 2010), gender (Gagnon et al., 2009), clothing type (Davis et al., 2011; Gavin, 2003; Havenith, 1999) and area of living in thermal comfort studies worldwide (Thorsson et al., 2007). However, studies on heat stress in tropical countries are still inadequate (Djongyang et al., 2010).
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Analysis of Outdoor Human Thermal Comfort within Three Major Cities in Egypt

Analysis of Outdoor Human Thermal Comfort within Three Major Cities in Egypt

The hourly average Robaa Index (RI) values for the three cities under investigation during the period from Jan- uary 2011 to January 2012 are shown in Figure 7. The numbers of days for different comfort categories in Alexandria, Cairo and Aswan cities respectively, during the period from January 2011 to January 2012 are shown in Table 7 through Table 9. As can be seen from Table 7, Alexandria city has quite human thermal un- comfortable cold weather (RI < 60) during eight months, from January to May and from November to January. It is also and May months have minimum number of quite uncomfortable cooling days (2 days) and (5 days) re- spectively. On the other hand, during the study period, Alexandria city has quite comfortable weather (65 ≤ RI < 75) in most months of the year with days number differs from month to another as can be seen in Table 7. It is noticed that the months of July, September and October are the most thermal comfortable months for the Alex- andria city. These three months have 87 days of quite comfortable. It is also found that, all total number of hot discomfort days for 50% of people (75 ≤ RI < 80) in Alexandria city during the study period is 8 days. Further- more, the discomfort index did not exceed 80 during the study period.
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Outdoor thermal comfort and summer PET range: A field study in tropical city Dhaka

Outdoor thermal comfort and summer PET range: A field study in tropical city Dhaka

17 Figure 3. Percentage frequency for the TSV across different sites The largest amount of data (19% each) were collected in CAEW and TRA2NS. The first one being a commercial area and home to three universities, the number of pedestrians was remarkably high. The second site, which is a traditional area with residential as well as commercial activities, also showed high pedestrian occurrences. This is due to the commercial activity and the connectivity of the street itself to other neighbouring areas. The formal residential areas, FRA1EW, FRA2EW and FRA2NS, although predominantly residential neighbourhoods, also contained small and medium scale businesses. Most of these are garment buying houses (mediator agencies between the retailers and clothing manufacturers) for the garment industry. This has generated high pedestrian movement in the area. The pedestrians are typically employees in the offices as well as the residents in the neighbourhood. Traditional residential areas TRA1EW and TRA1NS, on the other hand, are located at the edge of the respective neighbourhoods. The areas have similar commercial activities as TRA2NS. The pedestrians visible in these streets are mainly the residents of the area. The percentage of people in the educational area ECA is also less (6%). This is because the population is mainly students who gather here for academic or recreational purposes.
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Classification and mapping of urban canyon geometry using Google Street View images and deep multitask learning

Classification and mapping of urban canyon geometry using Google Street View images and deep multitask learning

classification based on its geometric features has become an important basis for microclimate research in high-density areas. Existing classification metrics of urban canyon geometry often depend on a range of factors such as the aspect ratio (AR) [ 6 ], the sky view factor [ 7 ] and the canyon orientation (e.g., north-south, east-west) [ 8 ]. Among them, the AR, which is the ratio of the canyon height (H) to the canyon width (W) AR ¼ H=W, is an important factor for charac- terizing urban geometry. It has been used to classify street canyons into three basic categories (i.e., avenue canyons, regular canyons, and deep canyons) [ 9 , 10 ]. It was claimed in Ref. [ 6 ] that the generation of extreme thermal stress is closely related to various values of H=W. Different wind flow regimes in street canyons were defined in Ref. [ 11 ] based on H=W; in the increasing order of H=W, the roughness flow, wake
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Outdoor Microclimate Observation for Thermal Comfort in Harsh Desert Condition: A Study in Kashan Iran

Outdoor Microclimate Observation for Thermal Comfort in Harsh Desert Condition: A Study in Kashan Iran

Abstract Traditional architecture of the historical cities of Iran contains valuable lessons related to architecture and urban design. A group of these strategies are those used in outdoor urban spaces in desert cities providing a safe and sustainable microclimate for pedestrian. This research paper will highlight some of these strategies by doing a field study research in hot summer and cold winter in Kashan, a historical city of Esfahan Province. The weather data are collected in 11-12 July 2011 and 11-12 Jan 2012 by a mobile Kestrel Personal Weather station in the traditional part of the city. The collected data are analyzed for human thermal condition by UTCI (Universal Thermal Climate Index) on the psychrometric chart. The different thermal zones on this chart are compared with people’s behaviour according to their exposure time, clothing and activity. The collected weather data of observation days are compared in four levels of long-term meso climate, short-term meso climate, local climate and microclimate. To speed up the analyzing process a new software is designed called SIKRON. The result of this research has shown the effect of architectural strategies on modifying the microclimate condition in hot summer and cold winter for outdoor living in hot-arid climate.
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Analyzing the thermal comfort conditions of outdoor spaces in a university campus in Kuala Lumpur, Malaysia

Analyzing the thermal comfort conditions of outdoor spaces in a university campus in Kuala Lumpur, Malaysia

3.3. Output of urban canopy model: IES-VE IES-VE simulations were then used to assess the microclimate conditions and to explore the urban canopy layer (UCL) for validating the results that obtained from field measurements and from the out- puts of ENVI-met simulation to enhance its reliability. Therefore, the IES-VE simulations assessed the urban climatology by investigating wind velocity and solar radiation loads in the focused area of the UM campus based on a developed model from the open street map (OSM). OSM tool imports surrounding buildings, landscaping and roads directly into IES-VE Project. The study developed the imported model and validated its parameters based on site visit and information obtained from the management of UM campus in Table 2 . First, using CFD analysis, the study explored the condition of wind speed in the created IES-VE model from various directions. The reason behind evaluating the obtained model from different directions is owing to the highly diverse records of wind directions derived from both on-site measurements and the weather data file of Subang International Airport.
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Impact of Using Stabilized Earth Blocks on the Thermal comfort

Impact of Using Stabilized Earth Blocks on the Thermal comfort

There is more need in the field of urban development to provide a sustainable alternative to building facilities. Where the materials and construction method are chosen according to the surrounding economic conditions and these conditions are overcome by stabilized earth blocks, making use of the existing natural resources and producing building units from the compressed stabilized earth blocks. This research aims to use building units from compressed stabilized earth blocks as an alternative to traditional building materials and to achieve thermal comfort by reducing energy consumption through the use of program design builder to rationalize energy consumption to represent economic and environmental advantages. Building units manufactured from several types of earth and stabilizing materials were used by 8% cement of the total weight. The compressed stabilized earth blocks of mixtures were produced to meet the requirements of the Egyptian Code for earth Building. The study was conducted on a residential model for comparison with compressed stabilized earth blocks with local blocks units. Moreover, it is better to use cement an addition at 6% and 8% ratio to have a suitable compressive strength results, regardless of soil type without the need of using high percentages of cement which is good for environmental and economic points of view provides energy required to operate the building by 4.5% to 26% compared to local bricks, in addition to availability of earth in urban and rural areas, making it suitable in terms of construction cost for walls and types of roofs.
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Proposition of Regression Equations to  Determine Outdoor Thermal Comfort in Tropical  and Humid Environment

Proposition of Regression Equations to Determine Outdoor Thermal Comfort in Tropical and Humid Environment

solar radiation (direct or indirect) can sting the surface of human skin so that logically may cause a feel of very uncomfortable for human being (Figure 1). In addition, air velocity in the outside is generally greater than in closed room, thus also affect the positive process of achievement of thermal comfort by convection and sweat evaporation. The people who have a habit to go outside from a closed room to get some fresh air and in order to get more feel comfortable by convective process, is a clear example in this case. People who walk in open space (pedestrian), likely need greater air velocity that can improve the feel of comfort by touching fresh air on the skin surface, particularly in the tropical and humid area. Fatigue due to walking activities, can be balanced by a sense of comfort by touching a fresh wind on the surface of human skin and encourage evaporation of sweat. A field study conducted by Arens E and Ballanti D [11] also found significant effect of wind speed on human comfort for people in walk activities in open space.
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Effect of Vertical Urban Surfaces on Human Thermal Comfort in Outdoor Environment

Effect of Vertical Urban Surfaces on Human Thermal Comfort in Outdoor Environment

From the psychrometric chart it is evident that the city has comfort level of only 22.1%. With most of the green dots in the zone of higher humidity and temperature levels. Heat gain or loss in buildings is through walls, roof, ceiling, floor, and glass etc. i.e. the building fabric of envelope. The load due to such heat transfer is often referred to as heat gain or heat loss. It is possible through outer walls of the structures. In case of sunlit wall, the heat gain of the room will be more in comparison to a shaded one. The heat load in buildings are due to the direct sunlight through south-west direction. Maximum the surface area perpendicular to the solar radiation, more the heat gain through the surface. Maximum heat may occur on the surface during noon and due to the time lag it will reflect back to adjacent areas after few hours.
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