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Toward a Spatial Model for Outdoor Thermal Comfort

Toward a Spatial Model for Outdoor Thermal Comfort

4 Future Outlook 4.1 Thermal Comfort as an Urban Design Tool This new spatial-architectural model for thermal comfort has the potential to be used as an urban design tool, capable of aiding in the design of outdoor spaces, their adja- cencies and ultimately their programs. This presents a significant shift from current thermal comfort models, often used as verification tools or as a mechanism to inform users of how behavior, such as the increase or decrease of clothing layers, must be amended. In contrast, if it is assumed that spatial parameters such as wall and mean radiant temperatures as well as naturalness, for example, are statistically significant in determining thermal comfort, this provides architects an opportunity to leverage de- sign decisions around these parameters. For example, the materiality and color of external surfaces of buildings and ground may hold particular importance, as the sur- face albedo would contribute directly to both wall temperature and mean radiant tem- perature. The materiality of a building system has a direct relationship to structure; in this case, it is not difficult to imagine that structural systems, intrinsically tied to ar- chitectural quality and morphology, could thus begin to connect closely to outdoor thermal comfort. Designers too could begin to develop novel approaches to solar ac- cess or wind flow, for instance, so that artificial lighting or ventilation is decreased and naturalness is amplified.
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Thermal sensation and comfort model for inhomogeneous indoor environments

Thermal sensation and comfort model for inhomogeneous indoor environments

Sensitivity to thermal stimuli varies between different body surface areas. Nadel et al. [1973] ap- plied thermal irradiation to selected skin areas to determine local thermal sensitivity to warm stimuli. Sensitivity was measured by the effect of skin temperature changes on the sweating re- sponse. The temperature change of the face was approximately three times as effective as the same stimulus on the thigh. Chest, abdomen, and thigh areas were relatively similar in their sen- sitivity. The lower legs were relatively insensitive as compared to other skin areas. Marks [1971] also used the method of thermal irradiation to explore how sensations of warmth depend on the intensity and spatial extent of skin heating for the forehead and back. The results for both areas, forehead and back, can be described by the psychophysical power equation 3.1 with irradiation as the thermal stimulus. The forehead is much more sensitive to heating than the back. Stevens et al. [1974] broadened the scope of these studies by analysing power functions on regional differ- ences. All stimulated body areas showed the same spatial summation: the larger the stimulus area, the greater the estimated magnitude of warmth. Given the same stimulus area, the cheek is just about as sensitive as the forehead, whereas the lower arm and the calf are far less sensitive than the forehead. Crawshaw et al. [1975] summarized regional differences using weighting factors for a functional mean skin temperature determined by thermal sensitivities as well as area weighting. The weighting factors show that the lower leg, for example, is particularly insensitive to heat, but has about the same sensitivity to cold as the chest, thigh, and abdomen. This finding implies that functional warm and cold input may not be evenly distributed, an assumption that is also proven by my own experimental data and implemented in the psychological part of the model.
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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

To help architects and designers for better decision making in design procedure, some thermal indices are provided for prediction according to climatic condition. The first groups of thermal outdoor indices are based on thermal stress model. Cold stress indices such as Wind Chill Equivalent Temperature (WCET) are prepared for cold conditions. Heat stress indices such as Wet Bulb Globe Temperature (WBGT) are prepared for hot conditions. The second group of thermal outdoor indices are prepared base on heat budget model. They are capable to evaluate both cold and hot conditions such as Perceived Temperature (PT), Temperature Humidity Index (THI), and Universal Thermal Climate Index (UTCI). The latest index (UTCI) is based on comprehensive heat budget model of human biometeorology. It is being prepared by a group of specialists [1] and is supposed to cover all shortcomings of other indices [2]. In this research, UTCI is used for data analysis on cold and hot conditions of the studied places.
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Urban outdoor thermal comfort of the hot-humid region

Urban outdoor thermal comfort of the hot-humid region

When analysed based on thermal comfort votes throughout the investigated sites, it is concluded that votes on ‘comft-neu’ is relatively high compared to votes on ‘uncomfortable’, except for TM, where the difference is quite small. Thus, it is suggested that, even though the outdoor weather condition is extreme compared to indoor environment, people seem to be able to tolerate and compromise on the condition. Based on the spatial category with combined studied sites, the percentage of samples (doing either passive or active activities) voting for ‘comfortable’, ‘neutral’ and ‘uncomfortable’ are tabulated in Table 11 as follows:
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The influence of bioclimatic urban redevelopment on outdoor thermal comfort.

The influence of bioclimatic urban redevelopment on outdoor thermal comfort.

The influence of bioclimatic urban redevelopment on outdoor thermal comfort Karakounos I., Dimoudi A.*, Zoras S. Department of Environmental Engineering, Democritus University of Thrace, 67132 Xanthi, Greece One of the greatest environmental challenges for the sustainability of future cities is the mitigation of the urban heat island phenomenon and thus, improvement of outdoor comfort conditions for people. The emphasis of this work is to analyze how mitigation techniques in a dense urban environment affect microclimate parameters and outdoor thermal comfort. The quantitative differentiation of outdoor thermal comfort conditions through bioclimatic urban redevelopment for an area in the city of Serres, Greece is investigated. The main bioclimatic interventions concern the application of cool paving materials, the increase of vegetated areas and the creation of water surfaces. The analysis and comparison are performed for a hot summer day with the ENVI-met model. Software simulations regarding microclimatic and outdoor thermal comfort conditions are performed for the daytime period 06.00 to 20.00 (14 hours) at the height of 1.8m from the ground. The examined parameters are air temperature, surface temperature and mean radiant temperature (T mrt ).
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Outdoor thermal comfort by different heat mitigation strategies   a review

Outdoor thermal comfort by different heat mitigation strategies a review

measuring air temperature and humidity in 21 parks in Addis Ababa showed that plant types, NDVI (Normalized Difference Vegetation Index), and shape and size of the parks have appreciable correlations with the cooling effect. The maximum park cooling effect (PCI) they found was 6.72 ˚C. Moreover, they measured the maximum spatial park cooling distance (PCD), which was 240m. This means the cooling effect of a park could be felt up to 240m far from the park. By comparing different plants (i.e. Acacia tortilis, Eucalyptus spp., Grevillea robusta, Cupressus lusitanica and Olea), they showed Eucalyptus spp has the most cooling effect; while Grevillea and Cupressus have the minimum effect.
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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

-being could be related to climate and weather. Since park users would always look at weather conditions when doing outdoor activities, designers should apply the ergonomics factors as influential aspect for outdoor spatial design. In addition, urban parks offer the public some release from the pressures of urban environments and everyday living. Microclimatic condition wise, there may be limitations to the thermal conditions during daytime that may affect prolonged usage of the outdoor parks. An assessment of human responses to the outdoor environment and the individual user's experience is necessary to determine the people's understanding of the condition. The setting of an outdoor park pointedly influences how that space is perceived and used.
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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

Fig. 7. Air temperature and solar radiation variations in all study spaces from 11:00 to 16:00. 3.2. Results of ENVI-met simulations Fig. 8 presents the spatial representation of air temperature. It is ap- parent that the highest level of temperature difference between the existing outdoor spaces, comparing the lightest and darkest colored zones in the figure, is observed at 14:00 and 16:00. On the contrary, less temperature spatial variations can be seen at 10:00 and 18:00 indicating a more homogeneous temperature distribution. The air tem- perature of the majority of spaces at 10:00 range between 28.85 °C and 29.85 °C while at 16:00, the temperature goes slightly higher than this range. However, the air temperature in a considerably high portion of the study areas ranges between 30.85 °C and 32.85 °C at both 14:00 and 16:00 demonstrating 2–3° of temperature increase. Comparing all spatial distributions at various times of the day, it is inferred that most of the spaces surrounded by building blocks have a relatively lower level of air temperature in comparison to the other spaces. One of the possible reasons for this is better levels of shading achieved as a result of the blockage of sun radiations by the surrounding buildings obstruction.
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Outdoor Universal Thermal Comfort Index Climatology for Alaska

Outdoor Universal Thermal Comfort Index Climatology for Alaska

The clothing model [36] simulates people’s adjusting their clothing to the out- side conditions. Insulation changes depending on ambient temperature. At temperatures below −20˚C, the clothing model assumes special clothing. Cloth- ing insulation values stem from data of actual behavior in the field [36]. A partial clothing approach is used. It accounts for the head and face being covered diffe- rently than the torso. It assumes the face to be exposed to the ambient air. Movement of the person and wind reduce thermal and evaporative clothing re- sistances. At ambient temperature, radiation, relative humidity and wind mod- ulate the physiological response while the clothing remains the same. The in- corporated comfort model uses physiological states (skin temperature, core temperature, sweat rate, skin wittedness, etc.) to predict thermal sensation res- ponses to steady state and transient conditions.
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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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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

Urban microclimate is affected by the configuration and orientation of the streets, heights of the flanking buildings and associated features (Krüger, Minella and Rasia, 2011). Several studies (Emmanuel, Rosenlund and Johansson, 2007; Lin, Matzarakis and Hwang, 2010) have examined the direct association between common urban geometry parameters, such as the H/W ratio (Height/ Width ratio) or SVF (Sky View Factor) and thermal comfort sensations using PET (Physiologically Equivalent Temperature) thermal index. Lin et al. (2010) have applied the RayMan model (Matzarakis, Rutz and Mayer, 2010) for predicting long-term thermal comfort on a university campus in central Taiwan (23 0 42’ N, 120 0 26’ E, 23m a.s.l. (above sea level)) using PET. On the other hand, (Emmanuel, Rosenlund and Johansson, 2007) have adopted a numerical simulation method and reported a decrease in PET when the H/W ratio is increased from 1 to 3 in tropical climate in Colombo, Sri Lanka (6 0 9’N, 79 0 9’ E, 7m a.s.l.). Thus, narrow streets were identified as providing better shading for the pedestrians compared to wide streets. Bourbia & Awbi (2004) in a theoretical study have simulated the shading conditions by combining different H/W ratios with various street orientations and tree positions for hot-dry climate at latitude 33 0 N. Ali-Toudert & Mayer (2007a) have examined the effects of galleries and overhanging facades on the thermal comfort conditions of street canyons with different aspect ratios located under hot and dry climate in Ghardaia (32 0 40’ N, 503m a.s.l.) in the Algerian Sahara. They concluded that the appropriate choice of H/W-ratio and orientation can lead to a substantial amelioration of the microclimate at street level and thus create favourable comfort conditions for pedestrians.
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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

Thermal comfort can be broadly divided into two main categories, physical comfort and psychological comfort. Physical comfort deals with the body and psychological comfort deals with the mind and thinking of the user. Physical and psychological discomfort thus affects the spatial experience of the user. In different weather conditions, people’s response to microclimate will vary, even if only subconsciously, leading to a different uses of these open spaces. Thermal comfort of outdoor spaces was always been a challenging aspect for composite climate of Delhi. From historic times we have seen various methods to counter the thermal discomfort in neighborhood areas. These methods includes the provision of water bodies, green areas, vegetated areas etc. Due to urbanization these natural areas are reduced in size. Provision of water bodies and vegetated areas is now difficult to accommodate in the neighborhoods. This resulted into higher temperature in neighborhoods. Cities gives out substantial amount of heat back to the nature which resulted into urban heat island effect, if we see it on a broader scale.
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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

Thermal comfort had been discussed since 1930 [9]. There are two approaches to thermal comfort: the steady state model and the adaptive model. The adaptive model is based on the theory of the human body adapting to the outdoor and indoor climate [9]. Human thermal comfort can be defined as the condition of the mind in which satisfaction as a thermal comfort. Fabbri [10] defined the comfort as the result of the interaction of many parameters of physical, physiological, psychological, social and culture rights. Thermal comfort depends on the architecture, clothing, the habits of eating and the climate. The discomfort is caused by a vertical air temperature difference between the feet and the head, by an asymmetric radiant field, by the local convection cooling or by contact with a hot or cold floor [11]. The mean radiant temperature (Tmrt) indicates the level of radiant temperature received by the human body (Fig. 2). The radiation includes all the radiative fluxes (direct, diffuse, reflected solar radiation and long-wave emissions from the surfaces [12]. Mean Radiant Temperature is considered as the most important factor affecting the human thermal comfort in an outdoor urban area [13]. The value of Tmrt is the sum of all short-wave and long-wave radiation fluxes absorbed by the human body that affects its energy balance and human thermal comfort [14]. Peng et al., [15] confirmed that the Mean Radiant Temperature is a more accurate indicator than air temperature to evaluate the thermal comfort. Thorsson et al., [16] came to the same conclusion, stating that the Mean Radiant Temperature is the most important meteorological parameter governing the human energy balance and the thermal comfort.
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Development of outdoor thermal comfort model for tourists in urban historical areas; A case study in Isfahan

Development of outdoor thermal comfort model for tourists in urban historical areas; A case study in Isfahan

As one of the most diverse and largest industries in the world, tourism industry is the paramount source of income and employment opportunities for many countries in the world. Due to its economic and social significance, tourism industry has increasingly become the center of attention for many governments. Nowadays, it is also one of the key tenets of the world’s economy and one of the fastest growing industries in the global economic development. Creating appropriate conditions for the development of tourism industry is essential. Amongst the main natural factors affecting tourism, climate has a crucial role [1,2]. Climate is a critical factor in determining the touristic areas [3,4] and affects tourism demand in different seasons [5]. Tourists are more sensitive to climate conditions than local people [6]; they are usually looking for a climate where they don’t have a feeling of thermal discomfort and dissatisfaction [7]. Providing information about the right time of visit help tourists schedule their time [8]. The information about the climate conditions of touring days is greatly important for tourism planners [9]. Integrated evaluation of the physical beauty and thermal comfort conditions of touring sites improves the capabilities of touristic areas [10]. Analysis of climate data [11] and climate information maps are useful for tourists to make the best decisions [12,13]. For instance, very few tourists visit the Sun Moon Lake in Taiwan. As most of the visitors are from China, it is recommended to provide appropriate climate information about the thermal comfort sensation of Chinese people for other visitors to make a visit [14].
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Spatial configuration, building microclimate and thermal comfort

Spatial configuration, building microclimate and thermal comfort

When we talk about different kinds of spaces on the building scale, conventionally these are divided into indoor space, outdoor space and semi-outdoor space, reflecting their architectural functional design. Indoor space refers to space that is surrounded by walls, windows or doors and covered with ceilings, roofs or roof windows. It is the most common and important space for the occupants’ daily life. It might be a closed space that is separated from the outdoor environment. The outdoor space is defined as the space included in the building, but lacking a ceiling, roof or roof window; hence a space that is directly exposed to the natural environment. Courtyards, patios and gardens are the main components of this category. In this context, a courtyard is identified as having a small height-to-width ratio and a patio is identified as having a large height-to-width radio. A garden is a big green space that is not completely surrounded by rooms. The semi-outdoor space, which is also known “grey” space or “buffer” space in architectural design, is a space featuring a semi-enclosed wall or roof. The semi-outdoor space is an important component in architectural spatial design. It can create various spaces and can connect the indoor spaces and outdoor spaces flexibly. The outside corridor, terrace, balcony and veranda are the main components used as transitional space. It should be noted that the three kinds of spaces can be transformed into each other through changing the spatial boundary conditions.
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The impact of increasing urban surface albedo on outdoor summer thermal comfort within a university campus

The impact of increasing urban surface albedo on outdoor summer thermal comfort within a university campus

ENVI-met v.4.1 Pro (Bruse 2015) is a high resolution computational fluid dynamic (CFD) program with the grid cell size of 0.5 to 10 meters. ENVI-met includes humidity and air temperature (by advection diffusion equations), turbulence and wind flow (by the non- hydrostatic incompressible NavierStokes equations in the Boussinesq-approximated form). One of the main benefits of using ENVI-met compared to the other CFD models is the fact that the evapotranspiration of vegetation is included in this model. There are two main input files for running a simulation by ENVI-met; the input file (.in) and the configuration file (.cf) (Bruse 2004). The input file is the model that describes the physical properties of the simulation area including buildings, ground surface and plants. The configuration file refers to the initial weather data, the duration, time and data of simulation, and the thermal
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The Dependence of Outdoor Thermal Comfort on Urban Layouts

The Dependence of Outdoor Thermal Comfort on Urban Layouts

The output generated files can be separated into two groups: main data files; contain the complete state of the 3D model, including the atmosphere, surface and soil. Receptor files; these files are generated if were defined re- ceptors inside the model area to watch specific points in more detail. In this paper, the simulations were initiated using data obtained from a Hashtgerd weather database on Meteonorm software, Version 6.0, and upper air data from Tehran Mehrabad observations (Table 4).

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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

Urban density and geometry are important urban design elements. A given urban density can result from independent design features that affect urban climate in different ways, such as: fraction of urban land covered by buildings, distances between buildings, and average height of buildings. The height of buildings is a design feature that can affect urban climate and outdoor thermal comfort in many ways. Reference [3] shows that wind speed and natural ventilation at street level are decreased when all buildings are of the same height. The height-to-width (H/W) ratio refers to the ratio between the height of buildings and the width of the streets and sidewalks that separate them. Reference [4] shows that, under low latitude conditions, the H/W ratio and street canyon orientation has a considerable effect on solar shading and urban microclimate. As the H/W ratio increases, the air temperature decreases; during some hours of the day, mean radiant temperature and surface temperature drop considerably [5]. The most comfortable conditions were found for narrow streets with tall buildings (higher wind speeds, lower surface temperature and meant radiant temperature).
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Nudging the adaptive thermal comfort model

Nudging the adaptive thermal comfort model

The provision of thermal comfort for building occupants stands out as one of the largest end- uses of energy in the built environment, bearing significant responsibility for greenhouse gas emissions and their destabilizing effects on our global climate system (Lucon et al., 2014; Berardi, 2017). One of the more common architectural answers to these challenges is climate- responsive or passive design of buildings, where natural ventilation is substituted for mechanical conditioning to deliver comfortable indoor environments while at the same time zeroing energy demand for heating, ventilation, and air-conditioning (HVAC). Where external climatic conditions or the building program are not amenable to exclusive reliance on natural ventilation, the hybrid approach known as mixed-mode (i.e., a combination of operable windows and mechanical conditioning) represents an alternative low-energy design strategy. By forestalling the onset of mechanical conditioning for as long as outdoor weather conditions permit, a mixed-mode design minimizes HVAC energy demand without compromising occupant thermal comfort. Successful implementation of a mixed-mode strategy includes a relaxation of the conventionally tight deadband between heating and cooling setpoints. Figure 1 shows reductions in annual HVAC- energy consumption of roughly 7-15% for every degree Celsius expansion in either direction beyond a temperature control dead-band of about 2 K (Hoyt et al., 2015). Utilizing natural ventilation is one mechanism for maintaining comfort within those wider temperature ranges. Significant energy savings can therefore be achieved through an operational change as simple as nudging setpoint temperatures (Ghahramani et al., 2016).
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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

4. Methodology The importance of new green branches of science aiming to find solutions to environmental challenges has been internationally considered as undisputable [7]. Numerical simulations using ENVI-met code were applied due to its high capabilities and few data entries. The program uses a three-dimensional computational fluid dynamics and energy balance model; the simulation study can analyze unlimited number of points in the model. It is used to simulate the impact of certain urban design strategies on thermal comfort at a certain location [8]. Nonetheless, the study is limited to the moderately warm-wet climate of Pecs. Although some of the findings may be generalized, the conclusions of the study are not necessarily valid throughout moderately warm-wet climate groups, since there are climatic and considerable variations between different cities in terms of size, planning principles, proximity to the sea, and topography, etc. Moreover, visual and acoustical comfort performance is not investigated here. Moreover, due to the diverse scenarios and meteorological conditions, the field measurements could not give the total conclusion. In contrast, the Computational Fluid Dynamics (CFD) simulation method plays an important role in the research because of its means of modeling simplified and optimized. However, the methodology will be divided into four sections first one is describing the selected study site, second analyzing the street canyons of the chosen case, and summarizing the street canyon of the case study features, third, applying the ENVI-met software to simulate the urban microclimate with different street canyon geometries. Nevertheless, fourth section discusses the simulated results as well as draws the related conclusion.
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