Evaluating the effects of different mitigation strategies on the warm thermal environment of an urban square in Athens, Greece

The present study examines the effect of different mitigation strategies on the microclimate and thermal sensation in an urban open area in Athens. The microclimatic model ENVI-met was applied to simulate thermal conditions for a warm summer day (15.07.2010). Thermal conditions were assessed based on air temperature and the Mediterranean thermal sensation scales of the Physiologically Equivalent Temperature (PET) and the Universal Thermal Climate Index (UTCI). The spatial and temporal resolution of PET throughout the square was developed per design scenario and was compared to the Current design layout to analyse and quantify the effectiveness of the mitigation strategies on the amelioration of thermal conditions. Results showed that the combination of the design scenarios was found to be the most advantageous mitigation strategy. The average PET and UTCI reduction of 6.9 °C and 6.1 °C, respectively, achieved a 15.5% improvement in thermal comfort. The aim of this research was to set specific targets on thermal sensation improvement and, based on the obtained results, it suggests certain mitigation strategies that will allow the specification of the appropriate microclimatic interventions to improve thermal comfort to the desired extent in the context of developing urban design guidelines

Modeling thermal sensation in a Mediterranean climate-a comparison of linear and ordinal models

A simple thermo-physiological model of outdoor thermal sensation adjusted with psychological factors is developed aiming to predict thermal sensation in Mediterranean climates. Microclimatic measurements simultaneously with interviews on personal and psychological conditions were carried out in a square, a street canyon and a coastal location of the greater urban area of Athens, Greece. Multiple linear and ordinal regression were applied in order to estimate thermal sensation making allowance for all the recorded parameters or specific, empirically selected, subsets producing so-called extensive and empirical models, respectively. Meteorological, thermo-physiological and overall models - considering psychological factors as well - were developed. Predictions were improved when personal and psychological factors were taken into account as compared to meteorological models. The model based on ordinal regression reproduced extreme values of thermal sensation vote more adequately than the linear regression one, while the empirical model produced satisfactory results in relation to the extensive model. The effects of adaptation and expectation on thermal sensation vote were introduced in the models by means of the exposure time, season and preference related to air temperature and irradiation. The assessment of thermal sensation could be a useful criterion in decision making regarding public health, outdoor spaces planning and tourism. © 2013 ISB

Thermal perception of teenagers in a cool outdoor environment: A case study: Toplinska percepcija tinejdžera u hladnom vanjskom okruženju: Analiza slučaja [Toplinska percepcija tinejdžera u hladnom vanjskom okruženju: Analiza slučaja]

Subjective thermal sensation of late teenagers was examined aiming to reveal potential discrepancies in its estimation compared to adults. Since teenagers have different clothing habits and preferences from adults, it is important to know whether the conclusions reached by studies on thermal sensation, usually involving adults, can be also applied to teenagers. A group of late teenagers was interviewed, based on a structured questionnaire, in an outdoor environment during two winter days and under an unexpected Saharan dust transport event during the second day, while meteorological measurements were obtained by the closest to the interview site weather station. Moreover, the performance of the bioclimatic index Cooling Power in simulating subjects’ thermal sensation was evaluated. Although differences in clothing thermal insulation of late teenagers compared to that suggested by similar studies were recognized, generally the results of this study were in agreement with the findings of similar field surveys focusing on individual thermal sensation and with no evidence of effects of the dust transport event on thermal sensation. Cooling Power based on the Mediterranean thermal sensation scale predicted thermal sensation vote fairly well. © 2015, GEOFIZIKA, All rights Reserved

Data on multiple body parameters, microclimatic variables, and subjective assessment of thermal sensation monitored in outdoor environment

This paper describes two sets of data on multiple body parameters of five participants, on microclimatic variables, and on self-reported assessment of thermal responses, all monitored in the same outdoor urban environment. Data were collected during three seasons, summer, autumn and winter 2010–2011, in the city of Athens, Greece. Part of these data, collected during the summer period, is related to the research article entitled “Case study of skin temperature and thermal perception in a hot outdoor environment.” (Pantavou et al., 2014) [1]. © 2017 The Author

Machine learning and features for the prediction of thermal sensation and comfort using data from field surveys in Cyprus

Perception can influence individuals’ behaviour and attitude affecting responses and compliance to precautionary measures. This study aims to investigate the performance of methods for thermal sensation and comfort prediction. Four machine learning algorithms (MLA), artificial neural networks, random forest (RF), support vector machines, and linear discriminant analysis were examined and compared to the physiologically equivalent temperature (PET). Data were collected in field surveys conducted in outdoor sites in Cyprus. The seven- and nine-point assessment scales of thermal sensation and a two-point scale of thermal comfort were considered. The models of MLA included meteorological and physiological features. The results indicate RF as the best MLA applied to the data. All MLA outperformed PET. For thermal sensation, the lowest prediction error (1.32 points) and the highest accuracy (30%) were found in the seven-point scale for the feature vector consisting of air temperature, relative humidity, wind speed, grey globe temperature, clothing insulation, activity, age, sex, and body mass index. The accuracy increased to 63.8% when considering prediction with at most one-point difference from the correct thermal sensation category. The best performed feature vector for thermal sensation also produced one of the best models for thermal comfort yielding an accuracy of 71% and an F-score of 0.81. © 2022, The Author(s) under exclusive licence to International Society of Biometeorology

Air quality perception of pedestrians in an urban outdoor Mediterranean environment: A field survey approach

Perception plays a significant role on people's response to preventive measures. In the view of public awareness, the aim of this study was to explore factors that affect air quality perception and to reveal its potential patterns. Air quality perception of individuals, in terms of dust and overall air quality, was examined in relation to air pollutants concentrations, meteorological variables, personal characteristics as well as their thermal sensation and health condition. The data used were obtained from environmental measurements, in situ and from stations, and questionnaire surveys conducted in an outdoor urban Mediterranean area, Athens, Greece. The participants were asked to report their air quality perception and thermal sensation based on predefined scales. A thermal index, Physiological Equivalent Temperature (PET), was estimated to obtain an objective measure of thermal sensation. Particulate matter (PM10) and nitrogen oxide (NO) were associated with dust perception. Nitrogen oxides (NOx) and carbon monoxide (CO) were associated to air quality perception. Age, area of residence, health symptoms and thermal sensation also affected the perception of air quality. Dusty or poor air quality conditions were more likely to be reported when pollutants’ concentrations were increased. Younger people, participants residing in the city center, experiencing health symptoms or warm thermal sensation showed a trend towards reporting more unfavorable air quality conditions. © 2016 Elsevier B.V

Case study of skin temperature and thermal perception in a hot outdoor environment

Focusing on the understanding and the estimation of the biometeorological conditions during summer in outdoor places, a field study was conducted in July 2010 in Athens, Greece over 6 days at three different sites: Syntagma Square, Ermou Street and Flisvos coast. Thermo-physiological measurements of five subjects were carried out from morning to evening for each site, simultaneously with meteorological measurements and subjective assessments of thermal sensation reported by questionnaires. The thermo-physiological variables measured were skin temperature, heat flux and metabolic heat production, while meteorological measurements included air temperature, relative humidity, wind speed, globe temperature, ground surface temperature and global radiation. The possible relation of skin temperature with the meteorological parameters was examined. Theoretical values of mean skin temperature and mean radiant temperature were estimated applying the MENEX model and were compared with the measured values. Two biometeorological indices, thermal sensation (TS) and heat load (HL)-were calculated in order to compare the predicted thermal sensation with the actual thermal vote. The theoretically estimated values of skin temperature were underestimated in relation to the measured values, while the theoretical model of mean radiant temperature was more sensitive to variations of solar radiation compared to the experimental values. TS index underestimated the thermal sensation of the five subjects when their thermal vote was 'hot' or 'very hot' and overestimated thermal sensation in the case of 'neutral'. The HL index predicted with greater accuracy thermal sensation tending to overestimate the thermal sensation of the subjects. © 2013 ISB

Data on multiple body parameters, microclimatic variables, and subjective assessment of thermal sensation monitored in outdoor environment

This paper describes two sets of data on multiple body parameters of five participants, on microclimatic variables, and on self-reported assessment of thermal responses, all monitored in the same outdoor urban environment. Data were collected during three seasons, summer, autumn and winter 2010–2011, in the city of Athens, Greece. Part of these data, collected during the summer period, is related to the research article entitled "Case study of skin temperature and thermal perception in a hot outdoor environment." (Pantavou et al., 2014) [1]

Thermal sensation and climate: a comparison of UTCI and PET thresholds in different climates

The influence of physiological acclimatization and psychological adaptation on thermal perception is well documented and has revealed the importance of thermal experience and expectation in the evaluation of environmental stimuli. Seasonal patterns of thermal perception have been studied, and calibrated thermal indices’ scales have been proposed to obtain meaningful interpretations of thermal sensation indices in different climate regions. The current work attempts to quantify the contribution of climate to the long-term thermal adaptation by examining the relationship between climate normal annual air temperature (1971–2000) and such climate-calibrated thermal indices’ assessment scales. The thermal sensation ranges of two thermal indices, the Universal Thermal Climate Index (UTCI) and the Physiological Equivalent Temperature Index (PET), were calibrated for three warm temperate climate contexts (Cfa, Cfb, Csa), against the subjective evaluation of the thermal environment indicated by interviewees during field surveys conducted at seven European cities: Athens (GR), Thessaloniki (GR), Milan (IT), Fribourg (CH), Kassel (DE), Cambridge (UK), and Sheffield (UK), under the same research protocol. Then, calibrated scales for other climate contexts were added from the literature, and the relationship between the respective scales’ thresholds and climate normal annual air temperature was examined. To maintain the maximum possible comparability, three methods were applied for the calibration, namely linear, ordinal, and probit regression. The results indicated that the calibrated UTCI and PET thresholds increase with the climate normal annual air temperature of the survey city. To investigate further climates, we also included in the analysis results of previous studies presenting only thresholds for neutral thermal sensation. The average increase of the respective thresholds in the case of neutral thermal sensation was about 0.6 °C for each 1 °C increase of the normal annual air temperature for both indices, statistically significant only for PET though. © 2018, ISB

Evaluating thermal comfort conditions and health responses during an extremely hot summer in Athens

In summer 2007, in the city of Athens, Greece, extremely high air temperatures were recorded, inducing heat discomfort conditions in the urban environment. Four biometeorological indices were calculated in order to evaluate human thermal sensation and thermal comfort: Actual Sensation Vote (ASV), Thermal Sensation-Ginovi method (TS), Discomfort Index (DI) and Heat Load Index (HL). Data included measurements of ambient temperature, temperature of the surrounding ground surface, relative humidity, air pressure, wind velocity and solar radiation obtained from National Observatory of Athens (NOA) station. During this period the daily number of patients probably affected by heat in emergency department units of cardiac clinics of four public general hospitals in Athens was recorded. The results revealed high values of DI and HL indices, demonstrating severe heat stress conditions during the last ten day period of June and July, while the ASV tends to classify too many cases into the comfort zone compared to TS, DI and HL. The statistical analysis revealed a negative relationship between the number of heat affected patients and the estimated indices values. © 2010 Elsevier Ltd