Top PDF Urban outdoor thermal comfort of the hot-humid region

Urban outdoor thermal comfort of the hot-humid region

Urban outdoor thermal comfort of the hot-humid region

Thermal comfort can be perceived as one of the tools used to study the quality of the evironment in which humans live. It may function as an indicator to study changes in the physical environment in relation to human comfort level. Hence, it is suggested that urban monitoring in terms of its climate and landscape changes for Kuala Lumpur must be conducted and recorded closely because, as the biggest city in a developing country like Malaysia, Kuala Lumpur could not stop from experiencing rapid urban form changes or perhaps to slow down its processes due to inter-related needs of the economy and built environment in particular. However, in an attempt to improve the quality of life through economic development, the lives of the current and the future generations should not be jeopardized.
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Urban outdoor thermal comfort of the hot-humid region

Urban outdoor thermal comfort of the hot-humid region

Section A: details on the location, date, day, weather condition and others, Section B: details of the sample, such as name, age, health condition and others, Section C: tables on comfort judgment for the sample to tick and a few open-ended questions. Scale for thermal sensation Scale for thermal comfort

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Development of an adaptive thermal comfort equation for naturally ventilated buildings in hot–humid climates using ASHRAE RP-884 database

Development of an adaptive thermal comfort equation for naturally ventilated buildings in hot–humid climates using ASHRAE RP-884 database

Current standards are essentially based on either heat balance or adaptive models. The most notable example of the former is the predicted mean vote (PMV) model developed by Fanger (1972) , which is applied in International Organization for Standardization (ISO) 7730 ( BSI, 2006 ) and ASHRAE Standard 55 ( ASHRAE, 2010 ). The latter model is also used in ASHRAE Standard 55 ( ASHRAE, 2010 ) as the code for naturally condi- tioned spaces and in European Standard (EN) 15251 ( BSI, 2008 ) for buildings without mechanical cooling systems. In principle, the heat balance model analyzes thermal physiology in detail by assuming controlled steady-state conditions and high accuracy for all analyzed variables such as activity level, thermal resistance of clothing, air temperature, mean radiant tempera- ture, relative air velocity, and water vapor pressure in ambient air ( Fanger, 1972 ). In contrast, the adaptive model investigates the dynamic relationship between occupants and their general environments based on the principle that people tend to react to changes that produce discomfort by seeking methods of restoring their comfort levels ( Humphreys and Nicol, 1998 ). Such adaptation encompasses physiological, psychological, and behavioral adjustments simultaneously ( Brager and de Dear, 1998 ; Humphreys and Nicol, 1998 ; Humphreys et al., 2007 ). Therefore, the adaptive model provides greater flexibility in matching optimal indoor temperatures with outdoor climate, particularly in naturally ventilated buildings ( de Dear and Brager, 2002 ; Deuble and de Dear, 2012 ; Humphreys, 1981 ;
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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

Abstract—The outdoor thermal comfort is influenced by the perception and satisfaction of the pedestrians, especially in hot and arid climates. Accordingly, the researchers look for the appropriate methods to reduce the Urban Heat Island and thus to enhance the outdoor thermal comfort level of pedestrians. However, there is limited research conducted on the outdoor thermal comfort in hot and arid climate. This work is an investigation study conducted in an urban area (Haifa Street) in Baghdad city, characterized by an arid climate with very high temperatures in summer season reaching 50℃. This study focuses on investigating possible mitigation strategies to ensure how we could improve the thermal comfort at pedestrian level for an urban area with intricate Western design (high–rise buildings, a large spacing between the buildings, asymmetrical canyon geometry, and lack of vegetation). We created four different scenarios to assess the role of vegetation elements such as trees, grass, and different shading patterns. The evaluation was performed in the hottest day in summer. For each scenario, the mean radiant temperature, specific humidity, air temperature, and wind speed distributions have been analyzed using ENVI-met software. Thermal comfort is assessed using the PET thermal index (Physiological Equivalent Temperature) and Predicted Mean Vote (PMV). The results reveal that the PET index can be reduced to 10.4 ℃, the temperature can be decreased of about 2.4℃ and PMV to 3. The study shows how the urban factors such as the aspect ratio, vegetation cover, shadings, and geometry of the canyon are crucial elements that urban planners and municipalities have to take into account, especially for new urban developments. 
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Wind characteristics and outdoor thermal comfort assessment in East Malaysia

Wind characteristics and outdoor thermal comfort assessment in East Malaysia

During southwest monsoon season, wind velocity is below 8m/s. Meanwhile, for northeast monsoon season, the wind velocity is in the range of 5 to 10 m/s. Generally, wind velocity is light and inconsistent during inter-monsoons seasons. Annually, Malaysia experiences monthly average relative humidity between 70% to 90%. Additionally, the country has around 6 hours of solar radiation per day on average (MetMalaysia, 2015). This study was aimed at enhancing our understanding of outdoor thermal environment in two different cities in East Malaysia, namely Kuching (i.e. Northwestern part of the Borneo island) and Kota Kinabalu (i.e. West coast of Sabah), as shown in Figure 1 and outlined in Table 1. The wind characteristics and outdoor thermal comfort levels were examined using weather data that correspond with the hot and humid tropical climate of Malaysia from two principal weather stations in Kuching and Kota Kinabalu.
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Optimization for Passive Design of Large Scale Housing Projects for Energy and Thermal Comfort in a Hot and Humid Climate

Optimization for Passive Design of Large Scale Housing Projects for Energy and Thermal Comfort in a Hot and Humid Climate

The results of the optimization process show that adaptations on three levels should be considered in the early design stage: materials, building geometry and urban layout. First, reflective glazing can reduce solar gain. Moreover external walls with a clay brick layer and two layers of mortar provide a good thermal performance for a low cost. Second, when windows are protected from solar gains with overhangs, the window size should be maximized for improving natural ventilation. The cross ventilation can be increased because of the buoyancy wind flows street canyon (Allegrini, Dorer, & Carmeliet, 2014). Furthermore, road width, building setback and obstacle heights effect solar gains and wind circulation importantly. Hence, natural ventilation can be improved by window size, orientation and urban density. Not considered in this analysis is that trees and plants can reduce incident solar radiation, (Villalba, Pattini, & Córica, 2014), but also wind permeability. As a conclusion, the model can be adapted based on many design parameters at different scale levels. In reality, selecting a main orientation for an urban area depends on the existing infrastructure, but a disadvantaged orientation can be compensated by changing the building geometry.
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Potential Contribution of Urban Developments to Outdoor Thermal Comfort Conditions: The Influence of Urban Geometry and Form in Worcester, Massachusetts, USA

Potential Contribution of Urban Developments to Outdoor Thermal Comfort Conditions: The Influence of Urban Geometry and Form in Worcester, Massachusetts, USA

UHIs form in urban areas mainly due to the characteristics of urban materials. In comparison to natural materials in suburban areas, construction materials can absorb and hold more of the sun’s heat and gradually release it back into the environment. This occurs because of two main reasons: 1- most urban construction materials are impervious and watertight, and 2- these materials are usually darker than natural ones and therefore they collect more of the sun’s energy [3]. On a hot sunny summer day, surface temperature of urban areas can reach up to 27 to 50 °C hotter than the air [4], while vegetated surfaces remain significantly cooler. Characteristics of urban surfaces can be defined by surface reflectivity, availability of moisture and thermal mass of construction materials [5]. In addition to characteristics of materials, urban form and configuration of buildings play an important role in intensifying this phenomenon. Urban form and geometry can considerably change wind patterns and the amount of insolation urban surfaces receive. There is a correlation between physical configuration of an urban setting with the microclimate surrounding it. Urban configuration can ease wind velocity penetration within the city and increase or decrease temperature subsequently. Single high rise buildings for example, divert the wind in different directions and this helps adjacent street become ventilated [6]. Building’s form also affect the levels of shading achieved on the ground. A study in Dubai done by Thapar et al, shows that in hot-arid climate courtyard block form and denser developments can provide well shaded streets for pedestrians [7]. Urban geometry and form is characterized by Sky View Factor (SVF), height to width ratio (H/W) of urban canyons, and orientation of streets regarding sun a nd prevailing wind.
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Outdoor Universal Thermal Comfort Index Climatology for Alaska

Outdoor Universal Thermal Comfort Index Climatology for Alaska

Bio-climate studies typically apply the Köppen-Geiger classification (KGC) [28] [45]. Warm temperate (C), and snow (D) climates are subdivided according to their annual precipitation (second letter) and temperature (third letter) charac- teristics. The second letters f, s, and w indicate fully-humid, dry summers, and dry winters, respectively. The third letters a, b, c, and d indicate hot, warm, cool, and extremely continental summers to describe the impacts of warmth and arid- ity on vegetation at the regional scale [28] [45]. Unfortunately, many of the sur- face meteorological sites lacked or had too many missing precipitation data to calculate the KGC at the site scale. For the 370 sites with sufficient precipitation and temperature data year round, the KGC was determined using the available sample of the 1979-2017 period. Since the focus was on the thermal comfort at the actual elevation, in contrast to [28] [45], the observed 2 m temperature was used, i.e. no reduction to sea-level was made.
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Redefining "dominating" and "contributing" physical factors of indoor thermal comfort in hot-and-humid climate of Malaysia

Redefining "dominating" and "contributing" physical factors of indoor thermal comfort in hot-and-humid climate of Malaysia

shafizal@upm.edu.my ABSTRACT In many tropical countries, the cause of the thermal discomfort is mostly due to the presence of high humidity and high air temperature. Air movement, on the other hands, has been considered as the best method in improving the thermal comfort level for this region. Many researches had been conducted regarding the factors affecting thermal comfort for tropical countries and as a result several ideas had been introduced on how the factors affecting the thermal comfort. Most of the research conducted on thermal comfort for tropical countries combined two or more factors as a joint factor such as air temperature and humidity. With the combination of two or more factors (joint factors), the dominant factor among the main factors and how people react to each of these factors especially with the presence of other factors are still in question. The research explore on how people react to each of these three main factors which consequently provides the hierarchy of importance among the three factors. The paper exposes the ‘dominating” factor which is the air temperature that must be presence at all time to affect thermal comfort. The humidity level and air movement are defined as ‘contributing’ factors rather than joint factors in affecting thermal comfort for tropical countries since the presence of both factors can only influence the thermal comfort level depending on the air temperature level.
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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

Okeil [50] developed a built form named the Residential Solar Block (RSB), which was later compared with a slab and a pavilion court [51]. The RSB was found to lead to an energy-efficient neighbourhood layout for a hot and humid climate. Ali-Toudert and Mayer [52, 53] used the microclimate model ENVI-met to simulate the outdoor thermal comfort in the hot dry climate of Ghardaia, Algeria. They also studied the effect of different orientations of the urban canyon. It was concluded that the air temperature slightly decreases (and that the PET improves) when the aspect ratio of building height/canyon width (H/W) increases. Johansson [54] conducted
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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

One of the very few studies on the urban street microclimate which focuses on radiation fluxes confirms the advantage of shading towards a reduction of the radiant heat gained from a human body when compared to a person standing in a fully exposed location [6].Trees as shading elements are very important to urban design. One important impact of street trees on citizens is the reduction of thermal stress during hot meteorological background conditions [7]. There are a few studies on the effect of planting trees on improvement of urban areas especially streets according to thermal comfort. While green cover is one of the most important solutions for creating appropriate micro–climate in harsh climates, especially in hot & dry climates and increase in their seeding is one of the best option to higher the pedestrian comfort level. Street trees will be most effective in providing “true” shade. Trees should be located to maximize shade for pedestrians, such as along walkways and sidewalks. Tree can improve the ambient air temperature by up to 15 % [2]. Studies show that individual trees in high distances will have a little impact on comfort and cooling. Therefore, it has been recommended that it is more effective for urban sites to use several smaller groups of trees [5].
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Effect of Urbanization and Industrialization Processes on Outdoor Thermal Human Comfort in Egypt

Effect of Urbanization and Industrialization Processes on Outdoor Thermal Human Comfort in Egypt

Detailed studies on the effect of urbanization and indus- trialization on human comfort in Greater Cairo region, Egypt have been performed in this study. Four different districts in Greater Cairo region have been selected, namely Bahtim to represent rural area, Cairo Airport to represent suburban area, Abbasiya to represent typi- cal urban area and Helwan to represent industrial area. The data of surface dry, wet bulb temperatures and wind speed for two different periods have been used. The first period (1967-1976 and 1947-1956 for the rural and re- main three districts respectively) represents the old non-urbanized period while the second period (1990-2009 for all districts) represents the recent urban- ized period. Discomfort indices for the two periods have been calculated using Robaa's formula 4. The study re- vealed that urbanization and industrialization processes have resulted in the modification of local city climate. This modification involves the alteration of the local air temperature, humidity and wind speed which in turn cause human climate change. It could be concluded that the urbanization and industrialization processes at any locality cause increase of human serious hot uncomfort- able feeling which in turn leads to more hindering for the human activities while the rural conditions leads to op- timum weather comfort for further and more human ac- tivities.
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The Influence of Urban Geometry on Thermal Comfort and Energy Consumption in Residential Building of Hot Arid Climate, Assiut, Egypt

The Influence of Urban Geometry on Thermal Comfort and Energy Consumption in Residential Building of Hot Arid Climate, Assiut, Egypt

a Assistant Professor, Departement of Architecture, Assiut University, Assiut, 71516, Egypt Abstract Designing climatically responsive dwellings not only can achieve thermal comfort for occupants, but also can make a significant improvement in energy conservation. Consequently, interest in the microclimate around buildings in urban areas has increased because its affects other things; outdoor and indoor thermal comfort, energy consumption in heating and cooling, and the spreading of air pollution. This paper aims to investigate the influence of open spaces (outer courtyards) between building “Shallow canyons” with a H/W ratio of 0.24~0.6 in one of the urban patterns of youth housing sectors in New Assiut city and deep canyons with a H/W ratio of 4 in one of the new residential houses (El-Abrahimia and El-Moalemen complexes) in the center of Assiut city on indoor thermal comfort. A comparison was made between the two cases based on indoor thermal comfort, energy consumption and IAQ in hot arid climate.
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Harmonious accordance of indoor-outdoor thermal comfort and building energy performance by ameliorating urban microclimate in different urban block types in tropical climate

Harmonious accordance of indoor-outdoor thermal comfort and building energy performance by ameliorating urban microclimate in different urban block types in tropical climate

Introduction Courtyards are common urban arrangements; often regarded as micro-climate modifiers. The application of courtyard houses for hot-arid climate, in particular, is well- established and well-documented. But there is disagreement (Ratti, Raydan, and Steemers 2003) for the same in hot-humid climate due to little diurnal variation which may result in urban heat island effect and reduced wind effect. Meir, Pearlmutter and Etzion (1995) has also emphasised, courtyards can only act as micro-climate restoratives, when certain conditions are met .This opens up a prospect to look at courtyard arrangements again by altering its basic parameters such as, geometry, permeability and orientation. Since this pattern has been practiced in the stated climate for many years, specially in the vernacular architecture (Figure 1 b, c), it could be interesting to investigate how far they are applicable in terms of outdoor and indoor thermal comfort and building energy performance in an urban context. It is very unlikely that the same courtyard suitable for hot-arid climate will also be the best option for hot-humid climate.
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Simulation-based Approach to Optimize Courtyard Form Concerning Climatic Comfort in Hot and Humid Climate

Simulation-based Approach to Optimize Courtyard Form Concerning Climatic Comfort in Hot and Humid Climate

The courtyard form has a configuration that also supports natural ventilation (Ghaffarianhoseini et al. 2015). The process of daily changes in temperature and humidity in summer in hot-humid climate regions can be studied in three phases. In the first phase, during the night cool air descends into the courtyard and into surrounding rooms. The courtyard loses heat by radiation. In the second phase, at midday direct sunlight affects the courtyard floor. Some of the cool air begins to rise and leaks out of the rooms. This induces convective currents in rooms. At this phase, the courtyard acts as a chimney depending on its size. In the third phase, the courtyard floor is warmer than interiors and convective currents occur in the late afternoon. After sunset, the air temperature falls rapidly and the courtyard radiates heat and cool air begins to flow to the courtyard and from there to interiors (Gallo et al. 1988; Talib, 1984). During this entire process, due to their effect on solar radiation gain and air movements, courtyard dimensions and sizes of the windows and ventilation types preferred in surrounding spaces have a direct impact on interior thermal comfort conditions (Ok et al. 2007). Therefore, this study evaluates with a parametric approach, indoor comfort conditions of a building with a courtyard in hot-humid climatic region, which are affected and changed according to different courtyard dimensions, different orientation and different ventilation types. Building form and courtyard dimension alternatives evaluated in this study are taken from the author's master's thesis (Bekar, 2018).
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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

The enthusiasm of scientists to study on ther- mal comfort condition of semi-outdoor and out- door spaces has been raised since recent decade but it is needed to focus on more details and locations. Through representing a review on the prior stud- ies, it is understood that although the evaluation of thermal comfort in semi-outdoor spaces of various climates has been done up to now, the number of researches which specifically concentrate on to as- sess the human thermal comfort in semi-open ar- eas are few. Particularly, there is a lack of research- es on assessing thermal conditions of semi-outdoor areas in hot-humid regions. Moreover, it is need- ed to find a proper universal thermal index for vari- ous climate conditions. This index can help urban planner to evaluate thermal condition of districts in the world in understandable range. Finally, to pro- pose the practical software for simulation the ther- mal comfort of semi-outdoor spaces in easy and us- er-friendly manner.
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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

Abstract—Building shading is a tried and true strategy for passive cooling to reduce energy consumption. But shading also affects the mobility system outside of buildings. This paper analyzes the effects of building shading on outdoor thermal comfort. It focuses on building height and density as the two design parameters of urban built form and uses weather data and passive shading simulation to derive a measure of the effect of walking outdoors. The model is specialized to regions of extreme heat and humidity, drawing weather data from Abu Dhabi in the United Arab Emirates. The methodological developments are then demonstrated on four urban design schemes: high-density, low-rise; low-density, high-rise; low-density, low-rise; and high-density, high-rise. The results show that the optimal urban system for hot and humid locations, in terms of improving outdoor thermal comfort, comes from increasing the height-to-width ratio of the built urban form.
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Thermal comfort investigation of an outdoor air-conditioned area in a hot and arid environment

Thermal comfort investigation of an outdoor air-conditioned area in a hot and arid environment

An overall of 407 participants were interviewed as 192 during summer 2014 and 215 during summer 2015. The surveys were focused on nonathletes adults sitting for approximately 2 h and did not perform any physical exercise prior to taking the survey. Thus, the exposure to the specific environmental conditions was long enough to define their thermal comfort condition. The main objective is to combine temperature and relative humidity in terms of population’s comfort zone. The vast majority of the sample (over 95%) indicated no health problems such as asthma or recent surgeries. Thus, it is assumed that the recorded thermal sensation was not affected by any medical factors. The clothing insulation of men was 0.36–0.61 clo and for those wearing the traditional Arab cloth (Thob) was 1.05–1.23 clo while for women, the thermal clothing insulation is 0.57–0.61 clo and for those wearing the traditional women dress (Abaya) was 1.19–1.24 clo (Al-ajmi et al. 2008; ASHRAE 55:2004 2004). The survey selected a representative sample that accurately reflects the entire residents in Qatar. A total of 407 participants were interviewed face-to-face. The participants were 230 men and 177 women with the percentage distribution to be 56% and 44%, respectively. Eight out of ten of the participants for 2014/2015 summers were from the Middle East and North Africa (MENA) region and Asia which are considered to be relatively familiar with the local hot and arid climatic conditions. The rest of the individuals came from different
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Thermal comfort investigation of an outdoor air-conditioned area in a hot and arid environment

Thermal comfort investigation of an outdoor air-conditioned area in a hot and arid environment

Measured data analysis Field survey and measuring tools An overall of 407 participants were interviewed as 192 during summer 2014 and 215 during summer 2015. The surveys were focused on nonathletes adults sitting for approximately 2 h and did not perform any physical exercise prior to taking the survey. Thus, the exposure to the specific environmental conditions was long enough to define their thermal comfort condition. The main objective is to combine temperature and relative humidity in terms of population’s comfort zone. The vast majority of the sample (over 95%) indicated no health problems such as asthma or recent surgeries. Thus, it is assumed that the recorded thermal sensation was not affected by any medical factors. The clothing insulation of men was 0.36–0.61 clo and for those wearing the traditional Arab cloth (Thob) was 1.05–1.23 clo while for women, the thermal clothing insulation is 0.57–0.61 clo and for those wearing the traditional women dress (Abaya) was 1.19–1.24 clo (Al-ajmi et al. 2008 ; ASHRAE 55:2004 2004 ). The survey selected a representative sample that accurately reflects the entire residents in Qatar. A total of 407 participants were interviewed face-to-face. The participants were 230 men and 177 women with the percentage distribution to be 56% and 44%, respectively. Eight out of ten of the participants for 2014/2015 summers were from the Middle East and North Africa (MENA) region and Asia which are considered to be relatively familiar with the local hot and arid climatic conditions. The rest of the individuals came from different
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Thermal Comfort Assessment in the Hot and Humid Region of Paraguay: a Comparison Between Three Methodologies

Thermal Comfort Assessment in the Hot and Humid Region of Paraguay: a Comparison Between Three Methodologies

location of the students in the classroom. Results indicate that those seated near the external wall more often declared thermal discomfort as they experienced greater climatic variance than those seated further inside. The high percentage of glass area in the three selected classrooms was one of the main factors that resulted in great influence of external conditions in the indoor environment (which often had a negative effect on thermal comfort). Therefore, general design guidelines adequate to hot-humid climate regions are proposed, such as the application of natural ventilation strategies and use of external shading devices.
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