A measurement-based framework integrating machine learning and morphological dynamics for outdoor thermal regulation

<p>Intensive urbanization and global warming are impacting the health and well-being of urban population. Nevertheless, urban environments with different design will have different micro and local climate conditions. Therefore, the application of parameters that assess thermal stress in urban areas, such as outdoor thermal comfort (OTC) indices are of paramount importance.</p><p>In this study the long-term (1961–2020) datasets of daily OTC indices for the city of Banja Luka (Bosnia and Hercegovina) were used. Detailed temporal analysis using Physiological Equivalent Temperature (PET), Universal Thermal Climate Index (UTCI) and Mean Radiant Temperature (Tmrt) was performed for: a) the entire research period, b) the decadal level, and c) defined extreme heat/cold stress categories. The results show intensive increase in extreme/strong heat days in the last twenty years, and the number of these days is five times higher than in the 70s and 80s. Decreasing tendencies are noticed in extreme/strong cold days towards the last two decades.</p><p>We also performed modeling of changes in mean daily air temperature according to IPCC climate scenarios RCP 2.6, RCP 4.5 RCP 8.5 until the end of the XXI century. The results point to significant positive changes under all three climate scenarios.</p><p>Furthermore, we analyzed PET, Tmrt and modified Psychologically Equivalent Temperature (mPET) indices during the hot summer days in June 2021 for different urban spaces (downtown, urban park, riverside) in Banja Luka. Results show that the downtown is the most most uncomfortable area in terms of OTC indices. Also, riverside had lower average <em>T<sub>a</sub></em>during summer daytime compared to urban park and downtown likely due to the synergy between river cooling effect (evaporation and sensible heat transfer) and tree shade.</p>

The globe witnessed a rapid development of the concepts of sustainability, smart architecture, and intelligent buildings during recent decades. The Healthy environment, particularly thermal comfort, is an essential concern for planners, urbanists, and architects to produce a healthy and thermally comfortable environment. A better understanding of the parameters that affect the Outdoor Thermal Comfort (OTC) will enable urbanists and environmentalists to control the microclimate and to enhance environmental performance. Several parameters affect the thermal comfort of human-being such as air temperature, mean radiant temperature (MRT), air velocity, humidity, metabolic rate, and clothing insulation. Assessing the MRT is considered the most challenging parameter in outdoor spaces. Recent researches recognized several approaches to determine the OTC in different climatic zones. The influence of different climates and user groups has significantly altered the range of responses for thermal comfort. This paper focuses on reviewing the current state of knowledge on how to assess the OTC and the MRT in the hot arid climate. Results confirmed the integration of the appropriate OTC index with other design tools to evaluate the OTC and the MRT. It also confirmed that Physiological Equivalent Temperature (PET) and Predictive Mean Vote (PMV) are the most common indices. While ENVI-met and RayMan are the most common software to assess the OTC.

Urban parks are an important component of urban public green space and a public place where a large number of urban residents choose to conduct outdoor activities. An important factor attracting people to visit and stay in urban parks is its outdoor thermal comfort, which is also an important criterion for evaluating the liability of the urban environment. In this study, through field meteorological monitoring and a questionnaire survey, outdoor thermal comfort of different types of landscape space in urban parks in Chengdu, China was studied in winter and summer. Result indicated that (1) different types of landscape spaces have different thermal comforts, (2) air temperature is the most important factor affecting outdoor thermal comfort; (3) because the thermal sensation judgment of outdoor thermal comfort research in Chengdu area, an ASHRAE seven-sites scale can be used; (4) the neutral temperature ranges of Physiological Equivalent Temperature (PET) and Universal Thermal Climate Index (UTCI) in Chengdu in winter and summer were obtained through research; (5) and UTCI is the best index for evaluating outdoor thermal comfort in Chengdu. These findings provide theoretical benchmarks and technical references for urban planners and landscape designers to optimize outdoor thermal comfort in urban areas to establish a more comfortable and healthy living environment for urban residents.

Assessing the outdoor thermal comfort conditions of exercising people in the semi-arid region of India

A quantitative evaluation model of outdoor dynamic thermal comfort and adaptation: A year-long longitudinal field study

The influence of the environment on the human beings in the aspect of different weather conditions is one of the main problems in the modern science. The degree of sultriness and coldness are decisive for the regular and stable work of the human thermoregulatory system. That affects the ability of the human beings to doing their work and everyday activities, and more important to the possible advent of different heat and cold related diseases. The weather influence is manifested in different ways, but the most notable one is the sensation to the thermal properties of the environment. That means how cold or how hot the human individual feels it is. Our research is focused on the calculation of three characteristics of the human thermal sensation called biometeorological indices. They are Predicted Mean Vote, Physiological Equivalent Temperature and Universal Thermal Climate Index. The RayMan model, which simulates the short- and long-wave radiation flux densities from the three-dimensional surroundings in simple and complex environment calculates also these indexes. A model setup is configured for Bulgaria and some adjacent territories and the computations are performed in fine-spaced grid on hourly basis. Assimilated ground measurements from the operative system ProData and data from the meteorological reanalyses ERA5 are used as weather input. The calculations are performed for four typical for each season months and the output is in form of three-dimensional digital maps of the considered indices. The results, which are spatially and temporally consistent, show either high and low spatial variability in different regions of the domain.

With the increasing impacts of climate change, there is a need for more accurate assessments of thermal comfort. This study addresses the limitations of current thermal indices in accommodating variations in clothing insulation, which is a critical behavioral adaptation influencing human thermal comfort. Many existing indices, such as Physiologically Equivalent Temperature (PET) and Standard Effective Temperature (SET*), rely on fixed clothing insulation values that may not accurately represent real-world conditions due to environmental, cultural, and behavioral variability. In contrast, some indices like the modified Physiologically Equivalent Temperature (mPET) and the Universal Thermal Climate Index (UTCI) allow for adjustable clothing insulation; however, UTCI's fixed values can be insufficient in regions with distinctive clothing practices, impacting its accuracy. This study evaluates the effectiveness of thermal comfort indices by conducting a field survey and questionnaire, collecting a total of 838 data sets. The analysis employs various methods, including sensitivity and specificity analysis, principal component analysis (PCA), alluvial diagrams, and polynomial charts. Findings highlight the limitations of fixed insulation values in indices such as PET and SET*, while emphasizing mPET's superior accuracy in predicting outdoor thermal comfort. PCA identified clothing insulation (Icl) as a significant personal factor affecting thermal comfort across diverse environments. This research reveals differing correlation coefficients at higher insulation levels (1.11-1.26 clo and 1.26-1.56 clo), with SET* exhibiting substantial variability (0.33) compared to mPET, which demonstrated the least variability (0.46). These results underscore the need to revise existing thermal comfort indices to incorporate more dynamic and context-sensitive insulation values for improved thermal predictions.

Outdoor thermal comfort is influenced by people's climate expectations, perceptions and adaptation capacity. Varied individual response to comfortable or stressful thermal environments results in a deviation between actual outdoor thermal activity choices and those predicted by thermal comfort indices. This paper presents a passive activity observation (PAO) method for estimating contextual limits of outdoor thermal adaptation. The PAO method determines which thermal environment result in statistically meaningful changes may occur in outdoor activity patterns, and it estimates thresholds of outdoor thermal neutrality and limits of thermal adaptation in public space based on activity observation and microclimate field measurement. Applications of the PAO method have been demonstrated in Adelaide, Melbourne and Sydney, where outdoor activities were analysed against outdoor thermal comfort indices between 2013 and 2014. Adjusted apparent temperature (aAT), adaptive predicted mean vote (aPMV), outdoor standard effective temperature (OUT_SET), physiological equivalent temperature (PET) and universal thermal comfort index (UTCI) are calculated from the PAO data. Using the PAO method, the high threshold of outdoor thermal neutrality was observed between 24°C for optional activities and 34°C for necessary activities (UTCI scale). Meanwhile, the ultimate limit of thermal adaptation in uncontrolled public spaces is estimated to be between 28°C for social activities and 48°C for necessary activities. Normalised results indicate that city-wide high thresholds for outdoor thermal neutrality vary from 25°C in Melbourne to 26°C in Sydney and 30°C in Adelaide. The PAO method is a relatively fast and localised method for measuring limits of outdoor thermal adaptation and effectively informs urban design and policy making in the context of climate change.

Introduction: Bioclimatic conditions are of great importance for all forms of tourism, especially for health tourism, as they should encompass therapeutic and prophylactic characteristics. Over the last three decades, tourism in Zlatibor has been continuously growing in terms of tourist numbers and the development of tourist infrastructure. This paper presents the bioclimatic and climatic conditions on Mount Zlatibor from the perspective of their impact on tourism. More precisely, it examines their influence on tourist movements on this mountain and their significance for the development of health tourism. Materials and Methods: Research data were obtained through the analysis of temperature, air pressure, humidity, insolation, and precipitation levels. Based on these data, physiological equivalent temperature (PET) values and the universal thermal climate index (UTCI) were calculated. Results: The obtained results of bioclimatic indices (PET and UTCI) indicate potential stress due to extreme cold in the mornings and evenings from late October to the second decade of March. Pleasant warmth prevails during the summer months in the mornings and evenings. In terms of health, the climate of Zlatibor is suitable for maintaining health, as well as for treating various lung diseases, anemia, heart and blood vessel disorders, especially thyroid disorders. Bioclimatic conditions closely correlate with tourist movements on Zlatibor, as evidenced by climate data and the results obtained from PET and UTCI calculations. Conclusion: Comparing tourist numbers over a five-year period reveals that bioclimatic conditions significantly influence Zlatibor's peak tourist season, which occurs during the summer months. This period offers the most favorable bioclimatic conditions, attracting the highest number of visitors to the mountain, especially those seeking health and recreational activities.

This paper presents a numerical study of the influence of external urban environmental conditions, namely, the solar radiation, in the building windows performance. A software that simulates the building thermal behaviour with complex topology, in transient conditions, is developed and used in the study of indoor air quality and indoor thermal comfort of the occupants of a building, under typical summer conditions. As management strategy was implemented a control system to the Heating, Ventilation and Air Conditioning (HVAC) using the PMV (Predicted Mean Vote) index as controllable variable. The studied university building is located in a Mediterranean-type climate in the south of Portugal. The indoor thermal comfort, evaluated by the PMV index, and the indoor air quality, evaluated by the carbon dioxide concentration, were obtained for all occupied spaces. In order to evaluate the implemented control strategy a set of results was obtained for the situations with and without HVAC system control. To exemplify the results obtained, two large compartments were chosen, one with windows facing South and the other without windows. As main conclusion, it can be stated that the use of the HVAC system controllable by the PMV index allows acceptable levels of thermal comfort within the category C of the ISO 7730 standard, and acceptable levels of indoor air quality within the limit proposed by the ASHRAE 62.1 standard.

The assessment of the thermal bioclimate is based on the human energybalance and derived indices such as Physiologically Equivalent Temperature (PET) or UniversalThermal Climate index (UTCI). These two indices were compared over a period often year based on hourly data in a middle European city with a temperate climate. Theanalysis performed shows that the differences obtained result from the different thermophysiologicalsettings of clothing insulation. For conditions with extremely high vapourpressure values, UTCI yields higher values than PET, which could describe the thermophysiologicalstress more appropriately.

This study seeks to assess the bioclimatic conditions of some selected stations in Nigeria from 1981 to 2010 using meteorological data input from the Nigerian Meteorological Agency (NIMET). The specific objectives were to analyze the spatiotemporal variability of the key weather parameters critical to bioclimatic conditions, evaluate the monthly and seasonal variation of the bioclimatic conditions and analyze the spatiotemporal variation of the human bioclimatic conditions over the area. The study applied the use of two bioclimatic indices, namely physiological equivalent temperature (PET) and Universal Thermal Climate Index (UTCI). PET was computed using the RayMan model, while UTCI was computed using the Bioklima model. The bioclimatic conditions were observed to vary seasonally as thermal stress levels particularly increased in the months of March to May and these months correspond to the pre-wet period of the year. The conditions, however, improved during the wet and dry periods. The early hours of the day (0600 Local Standard Time) were characterized mostly by no thermal stress conditions; however, the northern regions were cooler than the other parts of the country. The frequency of thermal stress categories for each station also revealed the threshold of the thermal stress condition over each station. The result from this study provides useful bioclimatic information applicable in the development of adaptive strategies and efficient planning with respect to the thermal environment.

Urban heat stress is a growing public health concern, particularly for soft mobility users such as cyclists and pedestrians. Understanding how urban and green infrastructure design, together with local micrometeorology, influences cycling behavior, is essential for developing effective heat mitigation strategies and promote sustainable urban mobility.Using the Brussels Capital Region (BCR) as a case study, this research utilizes data collected by Brussels Mobility, which deployed 18 monitoring stations to continuously record bicycle count and speed at 15-minute intervals. For the year 2023, the data was aggregated into hourly intervals, and Mean Radiant Temperature (Tmrt), Universal Thermal Climate Index (UTCI), and Physiologically Equivalent Temperature (PET) were computed for a 25 m × 25 m area surrounding each monitoring station. Additionally, the stations were classified as either green or non-green (26°C UTCI; >23°C PET). In warmer months, greenness also influenced cycling behavior, with a higher count ratio, especially on weekends and in the mornings. However, this effect was not observed when PET exceeded 35°C.Overall, thermal comfort, greenness and time of day have shown to affect cycling behavior. These findings highlight the need for further research to examine the role of greenery in cycling behavior, particularly given the limited route options available to cyclists.

This study presents a spatiotemporal analysis of bioclimatic comfort conditions for Iran using mean daily meteorological data from 1995 to 2014, analyzed through Physiological Equivalent Temperature (PET) index and Universal Thermal Climate Index (UTCI) indices, and bioclimatic clustering. The results of this study demonstrate that due to the climate variability across Iran during the year, there is at any point in time a location with climatic condition suitable for tourism. Mean values demonstrate maxima in bioclimatic comfort indices for the country in late winter and spring and minima for summer. Seven statistically significant clusters in bioclimatic indices were identified. Comparing these with clustering performed on PET and UTCI, the maximum overlaps between the two indices. In the following, the outputs of this research showed that most appropriate bioclimatic clustering for Iran includes seven clusters. These clustering locations according to climatic suitability for tourism provide a valuable contribution to tourism management in the country, particularly through marketing destinations to maximize tourist flow.

Urban thermal comfort analysis in hot-arid climates requires robust methodological frameworks to address intensifying heat stress. This study introduces a reliability-based thermal comfort framework using Monte Carlo simulation to evaluate six urban design interventions in Zahedan, Iran. Field measurements encompassed reference conditions, concrete gazebos with varying vegetation covers, and tree shade configurations. Monte Carlo simulation (n = 10,000) computed prediction uncertainties and probabilistic thermal comfort evaluations for Physiological Equivalent Temperature (PET) and Universal Thermal Climate Index (UTCI). A novel Thermal Comfort Reliability Index (TCRI) was developed integrating comfort probability and system reliability. The approach demonstrated excellent convergence (CV < 1%) and predictive capability (R2 > 0.999, RMSE < 1.0 °C). Results revealed critical deficiencies across all interventions. The best-performing configuration (concrete gazebo with full tree shade) achieved only 20.56% comfortable conditions. Hot failure probabilities ranged from 29.85% to 65.25%. UTCI demonstrated superior reliability versus PET, with 3.14 × higher performance and improvement factors of 1.7 × to 58.2 × . Sensitivity analysis identified mean radiant temperature (r = 0.942) and air temperature (r = 0.896) as dominant variables. Extremely low TCRI values (< 5%) indicate systematic failures requiring radical climate adaptation measures in hot-arid urban areas.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-33440-6.