Thermal Comfort Index Research Articles

On the identification and characterization of outdoor thermo-hygrometric stress events

Human thermal sensations are not controlled merely by the ambient temperature, but also by other biometeorological variables and personal factors. Therefore, thermo-hygrometric stress events need to be identified and monitored in addition to heat waves. The purpose of the present article is proposing a method for detection and characterization of thermo-hygrometric stress events, based on the rearrangement of heat waves indices and on new quantities. The Mediterranean Outdoor Thermal Comfort Index (MOCI) is used as a reference variable instead of the air temperature. The method is applied to Milan (Italy) for the 2022 summer, which: i) is the hottest in the period 1991–2020 with a temperature anomaly of 3.17 °C and ii) presents higher minimum temperatures (1.5 times higher) than those of the control period. The analysis of daytime values of MOCI demonstrates a cumulative MOCI higher than zero only in 2022. Hence, the lower fraction of data in the cold range determines a significant increase in the cumulative MOCI. The metrics on severe MOCI events in 2022 confirm the key-role of extreme temperatures. The proposed method is effective and, in this case, reveals the relevance of the cumulative thermal and thermo-hygrometric loads also in the absence of critical heating conditions.

Personal differences in thermal comfort perception: Observations from a field study in Brisbane, Australia

Despite substantial evidence emphasising the diversity in thermal comfort perception, conventional models like the Predicted Mean Vote (PMV) index tend to overlook personal variability. In buildings, this oversight leads to occupant discomfort, dissatisfaction, and inefficient energy use for conditioning. In the past, technological and logistical constraints made personalised field studies an arduous task. However, today recent advancements in low-cost sensor technology allow one to pervasively capture the immediate and personal thermal environment experienced by building occupants. Between summer and winter 2022, we conducted a field study across 13 office buildings in Brisbane, Australia, investigating the personal variability in thermal comfort perception. Throughout the study, we recorded over 135,000 samples of continuous personal indoor environmental data at participants' workspaces and collected 813 occupant survey responses. Analysing the data, we found (1) significant personal variability between subjects, evident in a personal mean discrepancy from the PMV index ranging from −1.5 to +1.5 on the thermal comfort scale; (2) a limited accuracy of the PMV index ranging between 35 and 40%; when predicting the subject’s thermal sensation vote, (3) offices with highly heterogeneous thermal indoor environments; (4) dissatisfaction with the workspace due to thermal discomfort and insufficient control of the personal thermal environment. Our findings suggest a high personal and spatial variability in thermal comfort, underscoring the need to consider these factors to improve the accuracy and occupant-focus of thermal comfort indices.

Enhancing indoor air quality and thermal comfort in indoor swimming pool facilities: investigating the impact of ventilation system configurations

This study focuses on enhancing indoor air quality and thermal comfort in indoor swimming pool facilities through the investigation of ventilation system configurations. Creating a comfortable and healthy environment in these facilities is crucial for the well-being of occupants and overall operational efficiency. The performance of the ventilation system significantly influences user comfort, energy consumption, and air quality. This research aims to analyze the impact of different ventilation system configurations on indoor air quality and thermal comfort parameters using computational fluid dynamics (CFD) simulations.To achieve the research objectives, CFD simulations were conducted using ANSYS Fluent ®, a widely used commercial CFD package. The simulations involved solving the governing equations for continuity, momentum, energy, and species transport, along with employing the k-epsilon turbulence closure model. A high-resolution mesh with over 5.6 million elements accurately captured the flow regimes and related phenomena.The study investigated various aspects of ventilation system configurations, including the placement and design of inlets and outlets, airflow rates, and distribution patterns. Evaluations were made based on key performance indicators such as indoor air quality parameters, thermal comfort indices, and energy efficiency metrics. Comparisons were made between different configurations to identify the most effective strategies for enhancing indoor air quality and thermal comfort.The findings of the study demonstrate the importance of ventilation system design in achieving optimal indoor air quality and thermal comfort in indoor swimming pool facilities. The results indicate that specific configuration choices, such as the use of circular inlets in the ceiling for improved spectator comfort and rectangular inlets in the side walls for better performance in the swimming pool area, can significantly impact thermal conditions and air distribution. Additionally, the study emphasizes the need for appropriate inlet grille height to ensure adequate air mixing and thermal comfort.The outcomes of this research provide valuable insights for architects, engineers, and facility managers involved in the design, construction, and operation of indoor swimming pool facilities. By understanding the impact of different ventilation system configurations, stakeholders can make informed decisions to optimize indoor air quality, thermal comfort, and energy efficiency. Ultimately, this research contributes to the development of sustainable and comfortable indoor swimming pool environments that cater to the needs of occupants and enhance their overall experience.

Studies on the Specificity of Outdoor Thermal Comfort during the Warm Season in High-Density Urban Areas

With the acceleration of urbanization in China, high density has become a significant feature of urban development. Although high-density development provides convenience, it also results in numerous environmental and climatic problems, such as the urban heat island effect, haze and extreme weather. These issues have reduced the comfort levels of the urban outdoor environment, led to increased energy consumption and had serious impacts on social development and the lives of residents. Improving the comfort of the outdoor urban environment is vital, especially in the current tendency for high-density urban developments. This paper focuses on a typical urban district in Shanghai, where we have gathered ambient meteorological data and human thermal sensation votes during spring and summer through monitoring and questionnaire research. Correlation analysis was conducted to examine the relationship between thermal sensation votes and comfort indexes (PET, UTCI). The findings indicated that the neutral PET during spring and summer was 22.30 °C and 24.55 °C, respectively, whilst the neutral UTCI was 18.75 °C and 26 °C, respectively, with the neutral temperature in summer being significantly higher than that in spring. Upon comparing the evaluation indices, it was found that the correlation between the UTCI and average thermal sensation votes was stronger; thus, the UTCI better represents people’s thermal sensation in the Shanghai area. Finally, regression analysis demonstrated that the acceptable PET range for 90% of cases during both seasons in Shanghai is between 25.0 °C and 32.1 °C, and the UTCI range is between 24.2 °C and 27.7 °C. This study presents theoretical criteria for evaluating environmental thermal comfort, laying the foundation for practical paths to optimize urban design for climate responsiveness in high-density urban areas.

A smart green mashrabiyya-shutter design for residential applications in Egypt

ABSTRACT The revival of traditional latticework mashrabiyya is continually urged in the Middle East and North Africa to address conflicting needs since it optimally balances environmental, social, and aesthetic functions. However, its material and craftsmanship costs and inflexibility are significant barriers. This study aims to provide a preliminary design for a green, smart mashrabiyya-like shutter responsive to climatic conditions and privacy needs in Egypt, manufactured with palm midribs, a waste material available in the MENA region due to annual trimming. The simple, yet responsive and traditional design outlined in this study has a considerable potential for residential applications not only in Egypt, but also in similar socio-environmental contexts. The design generation is based on three steps: 1) constructing a static model that maintains the basic socio-environmental needs, manufactured with palm midrib patterns, 2) modeling dynamic functions, using Grasshopper/Ladybug, through standardizing slats and deciding upon visibility and adjustable parts, and 3) integrating smart controls based on comfort indexes and indoor climatic readings. Using a simple circuit fitted with sensors, actuators, and a microcontroller, the design of a latticework shutter responsive to climate and privacy was generated. The concept depends on computing indoor weather data and comparing them to thermal, daylight, and wind comfort indexes. Consequently, automated decisions could be made to regulate the shutter parts in two ways: 1) its opening angle and 2) openness between the slats. Ultimately, the operating concept of the smart shutter in a room and automated flowcharts that make decisions in daytime and nighttime modes were proposed.

Experimental and Numerical Analysis on a Thermal Barrier Coating with Nano-Ceramic Base: A Potential Solution to Reduce Urban Heat Islands?

Adopting a multiscale approach is crucial for optimizing urban and building performance, prompting inquiries about the link between a technology’s local efficiency (building scale) and its broader impact (city-wide). To investigate this correlation and devise effective strategies for enhancing building and city energy performance, we experimentally examined a commercial nano-ceramic Thermal Barrier Coating (TBC) on a small-scale building and assessed numerically its influence on mitigating Urban Heat Islands (UHIs) at a city scale, translated in our case by the use of the thermal comfort index: the Universal Thermal Climate Index (UTCI). Our results reveal that the coating significantly curbs heat transfer locally, reducing surface temperatures by over 50 ∘C compared to traditional roofs and attenuating more than 70% of heat flux, potentially alleviating air conditioning demands and associated urban heat effects. However, implementing such coatings across a city does not notably advance overall efficiency and might trigger minor overheating on thermal perception. Hence, while nano-ceramic coatings indirectly aid UHI mitigation, they are not a standalone fix; instead, an integrated strategy involving efficient coatings, sustainable urban planning, and increased vegetation emerges as the optimal path toward creating enduringly sustainable, pleasant, and efficient urban environments to counter urban heat challenges effectively.

Natural cooling solution for thermally conditioning bus stops as urban climate shelters in hot areas: Experimental proof of concept

In response to the challenges posed by climate change and the growing heat patterns in cities, this study addresses the design and implementation of climate shelters integrated into public transport stops through the installation of surface radiant cooling modules. The aim is to improve the thermal comfort of short-stay users in cities in hot, dry climates. To this end, a fully sensorized thermal camera was used in a controlled setting to simulate real outdoor climate conditions and evaluate the efficacy of the radiant system. The prototype was modelled and characterized by means of in situ measurements, paying special attention to the temperature and radiant heat flux. The radiant modules maintained a temperature between 18 °C and 20 °C, even under oppressive conditions, with over 50% of the cooling flux due to radiation. The radiative performance of the prototype did not increase proportionally with increased water flow, stabilizing at high flows. The analysis of the thermal comfort index showed a decrease in feelings of discomfort of between 40% and 50% when the modules reached the set point temperature. The study shows that implementing these climate shelters in public transport stops such a bus shelters is feasible in hot, dry climates. This may be an effective strategy for mitigating the effects of climate change in urban areas and can be applied in any city that suffers from recurring heatwaves, thereby improving living conditions for city goers.

Protective facemask-induced facial thermal stress and breathing burden during exercise in gyms

During the COVID-19 pandemic, more than 90% of infections occurred in indoor environments such as restaurants and gyms. In particular, gym attendees are facing challenges of both infection risks and extra heat and breathing burdens with the use of protective facemasks (PFMs) during intensive exercise. To evaluate the PFM-induced thermal stress and breathing discomfort during high-intensity exercise, this study investigated the mechanisms of heat and air exchange between environment of inside and outside PFM via experiments and computational fluid dynamics simulations. In the experimental phase, the effects of the activity intensity and type of PFM on thermal and breathing comfort were tested. An uncomfortable microenvironment of the face covered by a PFM was found when the air temperature and absolute humidity increased by 4.1% and 23.1%, respectively, during high-intensity exercise, relative to the sitting scenario (30.8 °C, 0.026 kg/m3), together with a higher CO2 concentration (31.0% increase) and lower O2 concentration (8.3% decrease). Moreover, the masks newly designed provided better thermal and breathing conditions than traditional masks due to the larger surface area and lower thickness. In simulation phase, the model sensitivity analyses were conducted to assess the effects of eight factors on thermal and breathing comfort. The mask surface area is found to most highly affect not only the thermal comfort indices (temperature, absolute humidity) but also breathing comfort indices (the concentration of CO2 and O2). The study results provide an important reference for government policymaking, mask design, and public health.

Retrofit strategies to mitigate overheating linking urban climate modeling and urban building simulations with outdoor comfort. An urban sector in Malaga (Spain)

This work evaluates the cooling effect of retrofit strategies on urban buildings and outdoor comfort in an urban sector in Málaga on one of the hottest days. The methodology links urban climate modeling and urban building simulations with outdoor comfort. The solar reflectance (SR) of roofs, urban surfaces and green areas and their forestation increases after the retrofit. Only the SR façade remains the same, be it in the current or the retrofit scenarios: 0.3. Both façade retrofit strategies consist of an opaque double skin façade (ODSF) with ceramic or metal tiles. Energy cooling is reduced by 52.51% with ceramic and by 52.57% with metal ODSF while urban comfort improves after retrofit: Universal Thermal Comfort Index (UTCI) decreases by 0.62 °C and Mean Radiant Temperature (MRT) decreases by 2.58 °C. Simultaneously, seven points at the pedestrian level assess outdoor comfort in different urban canyons. UTCI decreases more with the metal than with the ODSF ceramic. Regardless the canyon height, the width ratio or the orientation, the UTCI decreases between 2.45 °C and 4.86 °C when under a tree and it decreases more as S/N canyons narrow. This methodology and insights help stakeholders, designers, planners, and policy-makers make data-driven decisions to mitigate overheating and UHI in Mediterranean cities with similar urban building and canyon morphology.

Urban heat islands characterized by six thermal indicators

The urban heat island (UHI) effect alters local thermal environment and affects thermal comfort of urban dwellers. However, the similarities and differences of the UHI when characterized by different thermal indicators (i.e., different types of temperatures and thermal comfort indices) remain poorly understood. Taking 30 major Chinese cities as an example, here we compared the spatiotemporal patterns and drivers of the UHI intensity (UHII) represented by six different thermal indicators, i.e., Ia (UHII represented by surface air temperature), Is (land surface temperature), Id (dew-point temperature), IHD (Humidex), Imrt (mean radiant temperature), and IUTCI (Universal Thermal Climate Index). These thermal indicators encompass temperature factors that capture changes in the natural environment and thermal comfort indices that reflect the human perception of changes in ambient heat and humidity. The results show that the ranking of the annual mean UHII is similar between the day and night (i.e., Is > IUTCI > Imrt > Ia > IHD > Id). From a seasonal perspective, the daytime Is and Imrt exhibit the highest variability among all indicators, while the IUTCI demonstrates the largest difference among climate zones. Regarding the UHI drivers, most of the UHI indicators (except Id) are negatively correlated with the urban-rural difference in vegetation index during the day. At night, the UHI indicators are negatively related to the climatic variables and the urban-rural difference in albedo. Our results by using the IUTCI to assess outdoor thermal comfort across local climate zones (LCZs) show that the inter-LCZ standard deviation of the IUTCI is 1.94 °C during the day and 2.16 °C at night. We believe that these results deepen our understanding of the UHII when characterized by different thermal indicators, especially from the human perception perspective.

Joint Measurement of Thermal Discomfort by Occupant Pose, Motion and Appearance in Indoor Surveillance Videos for Building Energy Saving

To accurately describe the thermal comfort of indoor occupant used to regulate heating, ventilation and air conditioning (HVAC) system is a key goal to reduce energy consumption in intelligent buildings. In this paper, we propose a noncontact measurement of occupant thermal discomfort behavior as an index of thermal comfort. The method takes the existing monitoring image data in the building as the input to infer the occupant thermal discomfort directly, which saves the cost because there is no need to install new sensors in the building and the occupant does not need to wear additional equipment. The framework combined three channels of body posture, motion and performance information to infer occupant thermal discomfort behavior, it consists of a human detection and crop module, a posture analysis module, an optical flow extraction module and a 3D convolutional neural network module. The three channels describe the actions from different perspectives, and the proposed method makes full use of the complementarity of the three modalities to identify the occupant’s thermal discomfort behaviors. Sixteen postures related to thermal discomfort were identified through a questionnaire, and 14,800 video clips containing these postures were collected for experimental evaluation. The results demonstrate the superior performances of our approach to the state-of-the-art techniques. The framework achieves noninvasive, cost-effective thermal comfort evaluation, and has potential value in improving energy efficiency of HVAC systems.

Characterization of Thermal Patterns Using Infrared Thermography and Thermolytic Responses of Cattle Reared in Three Different Systems during the Transition Period in the Eastern Amazon, Brazil.

In the Lower Amazon mesoregion, there are basically three types of production systems: the traditional (without shade and no bathing area), the silvopastoral (with shade and no bathing area), and the integrated (with shade and bathing area). It is considered that the type of production system influences the thermal comfort and productivity of cattle, so this research aims to evaluate the influence of these three types of production systems on the thermoregulation of Nellore cattle. The experiment was carried out on a rural property for raising cattle, located in Mojuí dos Campos, Pará, Brazil, during the transition period (June/July). Thirty bovine males (not castrated, aged between 18 and 20 months, average weight of 250 ± 36 kg, body condition score of 3.5, clinically healthy) were randomly divided into three groups: Silvopastoral System-SS (n = 10), Traditional System-TS (n = 10), and Integrated System-IS (n = 10). Climate variables were collected (air temperature (AT °C), relative humidity (RH %), wind speed (WS, m/s), solar radiation (SR), black globe temperature (BGT °C), and physiological parameters, such as respiratory rate (RR) and rectal temperature (RT)) at 6 a.m., 12 p.m., 6 p.m., and 12 a.m. to determine the thermal comfort situation of the animals. Thermographic images of the environment and animals were captured in order to obtain the body surface temperature (BST) through infrared thermography. The Benezra Thermal Comfort Index (BTCI), Environmental Stress Index (ESI), Equivalent Temperature Index (ETI), and Iberian Heat Tolerance Index (Iberian HTI) were used. The results showed that the silvopastoral system, with shading by chestnut trees and an ample vegetative area, presented better thermal conditions, with an average of 28.98 °C, in comparison with the traditional system (35.93 °C) and the integrated one (34.11 °C). It was observed that the body surface temperature of cattle did not differ significantly between the anatomical regions of the body and the studied systems (p > 0.05). As for the respiratory rate, the traditional system registered higher values, with an average of 41 movements per minute, indicating possible thermal stress (p < 0.05). The thermal comfort indices revealed that all systems presented moderate stress conditions during times of higher solar intensity. It is concluded that the silvopastoral system proved to be more favorable for cattle, providing shade and reducing thermal stress, which may have a positive impact on animal welfare and productivity in this region.

Thermal comfort and productive responses of 7/8 holstein-gyr cows subjected to cooling system

The objective of this research was to identify the influence of the evaporative adiabatic cooling system (EACS) on the thermal comfort and productive responses of dairy cattle, through multivariate analysis by principal components (PC), in the summer and winter seasons of the semiarid region of Pernambuco, Brazil. The data came from an experiment that included 16 multiparous lactating cows (7/8 Holstein-Gyr), randomly distributed in 4 sets, with 4 experimental phases and 4 treatments (0, 10, 20, and 30 min.). The multivariate analysis was carried out through PC for the thermal comfort indices, physiological variables, and milk production and composition. The highest milk production in the summer season was obtained for animals exposed to the cooling system for 30 min. In the winter season in the morning period, the use of the EACS for 10 min. was sufficient for improvements in milk production. The times of exposure to EACS caused changes in the composition of milk, for both seasons. Principal component analysis made it possible to verify a positive correlation of evaporative cooling with thermal comfort, physiological responses, and production and composition of milk of lactating cows.

DETECTION OF DISCOMFORT INDEX WITH REMOTE SENSING TECHNOLOGY: THE CASE OF ANTALYA PROVINCE

Abstract. Thermal adaptation and thermal comfort indices are critical in determining the thermal comfort of the outdoor environment. They also play an essential role in research on heat stress, an environmental threat that can affect individuals' productivity, health and even survival. Urban growth and the resulting expansion of impervious surfaces affect the thermal characteristics of a landscape by raising Land Surface Temperatures (LST). The resulting warming can lead to thermal discomfort, the prevalence of heat-related health problems, air pollution, increased water use and energy demand for air conditioning, among others. Recently, efforts to understand the effects of urbanization and landscape changes on indoor and outdoor temperatures have increased significantly. Together with remote sensing technology, this study aims to understand human heat stress, and geographic information system (GIS) is a tool used in the research. In the estimation of heat stress, besides temperature, physiological status, environmental impact and relative humidity factors are also important. The discomfort index (DI) is a heat stress indicator proposed by Thom (1959), which expresses the contribution of air temperature and relative humidity to human thermal comfort. The discomfort index proposed by Thom (1959) was calculated as DI=0.5Ta+0.5Tw (Ta: dry bulb temperature, Tw: wet bulb temperature) modified by SOHAR, Adar and Laky (1963). In the study, the dry bulb temperature, assumed to be equal to the air temperature, was taken monthly from MODIS LST data at 1km resolution. Relative humidity was produced by interpolating 73 meteorological data in the study area at 1km resolution. Wet bulb temperature is difficult to measure, so it was calculated from dry bulb temperature and relative humidity data so that the discomfort index as a measure of heat stress in the study area was calculated with a resolution of 1 km. The discomfort index was calculated monthly and annually and classified according to Thom's 4 comfort classes. According to the calculation results, Antalya's average discomfort index value for the whole year is 24.9 °C, indicating that Antalya is a moderately comfortable place. This value varies monthly, especially in April and October when the heat stress is the highest.

The effect of facade materials and coatings on urban heat island mitigation and outdoor thermal comfort in hot semi-arid climate

High urban temperature is generally associated with negative effects on building energy consumption, outdoor thermal comfort, air quality, and human health. Then it is necessary to find strategies to reduce urban heat island and improve outdoor thermal comfort. This research investigates and classifies facade coatings and materials with regards to urban heat island effect in hot semi-arid climate of Shiraz. The surface temperature of 20 common and modern building facade materials during two periods for five days and their effect on outdoor air temperature is investigated through field measurement. Additionally, to study the effect of each material on urban heat island and thermal comfort index, Physiological Equivalent Temperature (PET) of a neighborhood in Shiraz was simulated with ENVI-met software on June 22. The results show that during the day under direct sunlight, the living wall has the lowest surface and air temperatures, and as the nearby air temperature increases during the night, it lowers the temperature fluctuations both during the day and night. Materials with high albedo increase the Mean Radiant Temperature and PET index despite their lower surface temperature. Materials with high thermal mass and low emissivity have lower temperature. The living wall has the lowest PET index, indoor and outdoor surface temperature during the day. It can also result in 2 °C reduction of air temperature.

Optimizing demand-controlled ventilation with thermal comfort and CO2 concentrations using long short-term memory and genetic algorithm

Heating, ventilation, and air conditioning systems are the largest consumers of energy in commercial and residential sectors. Minimizing their energy consumption without compromising indoor air quality and thermal comfort would result in environmental and financial benefits. However, most buildings still utilize constant air volume systems with on/off control to meet the thermal loads. Previous studies show that CO2-based demand-controlled ventilation is the most widely used strategy to determine the optimal level of supply air volume. Conventional CO2 mass balanced models, however, do not take the thermal comfort level into account. This paper aims to develop and implement a practical and efficient optimization framework to help office building designers and operators enhance thermal comfort and indoor air quality while minimizing energy costs for ventilation using demand-controlled ventilation. The objective function was constructed to consider thermal comfort indices, indoor air quality, and ventilation power demand. Long Short-Term Memory networks in conjunction with a generic algorithm optimization were utilized to generate the search spaces and solve the objective function. The proposed optimization strategy achieved near-optimal results within approximately 1 h of computation time. The findings indicate a reduction of the average ventilation power by 5.6% compared to the current on/off control approach and a slight increase of 0.25% in ventilation power when compared against the minimum ventilation rate recommended by ASHRAE. Additionally, the optimized approach leads to a saving of 26.9 kg per day of greenhouse gas emissions in terms of carbon dioxide equivalent.

The effect of water and vegetation elements as microclimate modifiers in buildings in hot and humid tropical climates

Thermal comfort in buildings is determined by several aspects of the climate, such as external and internal wind speeds. Therefore, this research aims to analyze the effect of water elements and vegetation as microclimate modifiers in buildings, to obtain thermal comfort through air velocity and flow analysis. In this context, the field analysis emphasized microclimate parameters. Two cases were also encompassed, namely the interior space of a residential building and a shopping center. By using field measurements with quantitative methods, data were obtained through the analysis of the PMV (thermal comfort index Predicted Mean Vote), PPD (Predicted Percentage of Dissatisfied), and TSV (Thermal Sensation Vote). This experiment was conducted to determine the influential levels of the building water and vegetation on comfort and the thermal environment. Data analysis was also processed using a statistical approach, with airflow being simulated through CFD (Computational Fluid Dynamics) method. The results showed that the air movement occurring in the building to the comfort and thermal environment, through architectural elements, reduced the temperature and humidity in the room. This was due to the heat radiation outside the building, leading to an impact on the effective air temperature for the thermal sensation of visitors. In this case, the movement of air in the building with the placement of architectural elements, such as water, vegetation, and good ventilation, was important for various activities. These activities included the following, (1) providing positive value, (2) improving the quality of the indoor environment, (3) maintaining the stability of the thermal environment at the building scale, and (4) achieving a comfortable thermal sensation.

Assessment of Outdoor Thermal Comfort in Urban Public Space, during the Hottest Period in Annaba City, Algeria

In this study; the outdoor thermal comfort of the users of two urban plazas with different morphologies in Annaba city, Algeria, have been evaluated. First, field measurements of the microclimatic parameters took place; namely the air temperature and the relative humidity in the two urban plazas, during hot days. Then, these measurements were compared with the results of the numerical simulations carried out by ENVI-met software in order to validate the model. The outdoor thermal comfort was evaluated by microclimatic measurements as well as a questionnaire survey consisting of interviews during the measurement days. The main objective was to determine the neutral Physiological Equivalent Temperature (PET) and to examine the influence of urban microclimatic conditions on the subjective thermal perception of people, as well as to compare it with different indexes of thermal comfort. Hence, the aim was to compare the microclimatic parameters of the two plazas, with and without vegetation and to see their impact on the thermal comfort indices. The results show that there is a difference between the two morphologies. Moreover, vegetation and urban morphology influence the neutral values of the thermal comfort indices.

Thermal Comfort Analysis and Optimization Strategies of Green Spaces in Chinese Traditional Settlements

The spatial pattern of Weizi settlements features distinct regional characteristics. Moreover, it contains profound wisdom in terms of traditional construction; therefore, studies on its association with the microclimate have important implications for improving the quality of human settlements. In the present study, Guanweizi Village in the Xinyang City of Henan Province was used as an example to analyze and evaluate the thermal comfort of green spaces. The impact of peripheral water bodies on the thermal comfort of outdoor green spaces in the settlement was studied, and the association between the components of outdoor green spaces and physiological equivalent temperature as an indicator of thermal comfort was explored. Further, factors negatively affecting the thermal comfort of green spaces were analyzed through the grid method. Thermal comfort in the Weizi settlement is somewhat correlated with the coverage of water bodies, roads, soil, greening, and buildings. Increasing the water area and creating multi-level greening spaces are effective measures to improve the thermal comfort of green spaces in the settlement. Our findings provide a theoretical basis and a pioneering example for future practices of environment design for human settlements.

The influence of virtual environment on thermal perception: physical reaction and subjective thermal perception on outdoor scenarios in virtual reality.

Positive thermal perception can affect users' climate-controlling behavior, indirectly reducing a building's operational carbon emissions. Studies show that some visual elements, such as window sizes and light colors, can influence thermal perception. However, until recently there has been little interest in the interaction of thermal perception and outdoor visual scenarios or natural elements like water or trees, and little quantitative evidence has been found associating visual natural elements and thermal comfort. This experiment explores and quantifies the extent to which visual scenarios outdoors affect thermal perception. The experiment used a double-blind clinical trial. All tests were done in a stable laboratory environment to eliminate temperature changes, and scenarios were shown through a virtual reality (VR) headset. Forty-three participants were divided into three groups randomly, separately watched VR-outdoor scenarios with natural elements, VR-indoor scenarios, and a control scenario of the real laboratory, then finished a subjective questionnaire conducted to evaluate their thermal, environmental, and overall perceptions while their physical data (heart rate, blood pressure, pulse) was real-time recorded. Results show that visual scenarios could significantly influence thermal perception (Cohen's d between groups > 0.8). Significant positive correlations were found between key thermal perception index, thermal comfort, and visual perception indexes including visual comfort, pleasantness, and relaxation (all PCCs ≤ 0.01). Outdoor scenarios, with better visual perception, rank higher average scores (M ± SD = 1.0 ± 0.7) in thermal comfort than indoor groups (average M ± SD = 0.3 ± 1.0) while the physical environment remains unchanged. This connection between thermal and environmental perception can be used in building design. By being visually exposed to pleasing outdoor environments, the positive thermal perception will increase, and thus reduce building energy consumption. Designing positive visual environments with outdoor natural elements is not only a requirement for health but also a feasible path toward a sustainable net-zero future.