Actual Sensation Votes Research Articles

A Computational Fluid Dynamics Modelling Approach for the Numerical Verification of the Bioclimatic Design of a Public Urban Area in Greece

Recent recordings of urban overheating reveal a dramatic increase in cities’ population exposure to heatwaves. Heatwaves’ implications are escalated in urban environments due to the intensification of the Urban Heat Island (UHI) effect. To combat the overheating and UHI adverse effects, novel urban rehabilitation actions are needed based on reliable predictions of appropriate Key Performance Indicators (KPIs) (such as pedestrian-level air temperature and thermal comfort) for alternative design scenarios. The objective of the current study is to present the application of a previously developed Computational Fluid Dynamics (CFD) model for the calculation of urban microclimatic conditions for the assessment of the UHI and thermal-comfort conditions in a central urban area in the city of Heraklion in Crete, Greece. Empirical validation of the model is performed through comparisons with monitored microclimate data (i.e., air temperature, relative humidity, wind speed) and actual sensation vote recordings found in another research study. In compliance with the latter, the validation campaign is conducted for a typical hot summer day in July 2009 from 10:00 to 16:00. The model is then used to assess the UHI effects for both the existing urban configuration and a given suggested environmental upgrade of the space. Simulations of the existing situation reveal that the squares located in the studied area already stand for efficient resistances to urban overheating, and heat vulnerabilities are detected mainly in non-shaded traffic and pedestrian roads perimetric to the squares. Based on the CFD simulations, the suggested environmental upgrading plan exhibits a reduction in the peak mean air temperature of 0.46 °C, and thermal comfort is improved by at least 5% (based on SET) throughout the studied area in summer. At the same time, simulations of winter conditions suggest that there are limited potential pedestrian thermal-sensation and building heating penalties under the considered renovation scenario.

Analyzing outdoor thermal comfort conditions in a university campus in hot-arid climate: A case study in Birjand, Iran

Outdoor thermal comfort is an important factor in designing urban spaces influencing outdoor activities, social interactions, tourism, wellbeing, and health. Focusing on seasonal differences, this study investigates the thermal comfort conditions and the actual thermal sensation of subjects, and attempts to calibrate the scale of subjects' thermal sensation in a hot-arid climate. Experimental data were collected through a field questionnaire survey consisting of 1361 subjects and on-site monitoring in a university campus. The relationship between PMV and PET thermal indices and real thermal sensation of subjects was established. The evaluation of acceptable PMV range using the actual thermal sensation vote revealed that the common comfortable PMV range overestimated the thermal comfort with the comfortable PMV range being −0.1 to 0.9 in this climate. As a result, an extended PMV model was utilized to consider the effects of expectancy factor. The PET index has shown a stronger correlation with actual sensation vote where the neutral PET temperature range was determined as 16.4 °C to 25.3°C in the field study. Finally, the obtained correlations can be used for predicting actual thermal sensation in designing sustainable and appropriate urban spaces with a high frequency of use and improved comfort level in a campus in the hot-arid climate of Birjand.

Spatial environment design and comfort simulation of high-latitude building bottom based on geological conditions

In order to solve the situation that the temperature in the high-latitude area is large and the space comfort of the bottom of the building is poor, the bottom space environment of the high-latitude building based on geological conditions is designed, and the comfort of the space environment is simulated. The numerical simulation technology is used to simulate the temperature information of the bottom space of the building, and the temperature, velocity, and humidity fields of the space air at the bottom of the building affected by the geological conditions are obtained. Based on the characteristics of the high-latitude space environment, the design is applied to the single-core bottom space and the multi-core bottom space. The space environment at the bottom of the high-latitude building is divided into functional partitions of the bottom space; the outdoor open space thermal comfort model of Actual Sensation Vote (ASV) is used to simulate the wind environment, radiation distribution, temperature, and humidity distribution and simulate the comfort of the space environment at the bottom of the building. The analysis of the experimental results shows that the weather condition at 8:00 am is the most comfortable time for human body to feel. At this time, the thermal feeling in most areas of the indoor space is moderate, which shows that the method can accurately simulate the comfort of the space environment at the bottom of the building from the perspective of radiation distribution, wind speed distribution, and thermal comfort distribution, and the designed space environment function layout at the bottom of the building is reasonable.

Thermal comfort in the low energy building - validation and modification of the Fanger model

Nowadays, we spend most of our time inside buildings. Thus, ensuring adequate thermal comfort is an important issue. The paper discusses the issue of thermal comfort assessment in the intelligent low energy building “Energis” of Kielce University of Technology (Poland). The tests conducted in a selected lecture theater focused on collecting anonymous questionnaires containing thermal sensation and air quality votes of the respondents as well as performing measurements of indoor air parameters (air and globe temperatures, relative humidity, air velocity and CO2 concentration). Based on the obtained data a comparison has been done between the actual sensation votes of the volunteers and the calculation results performed with the Fanger thermal comfort model. Two indices have been considered in the paper: PMV (Predicted Mean Vote) and PPD (Predicted Percentage Dissatisfied). A modification of the model has also been proposed, which considers the impact of the carbon dioxide concentration on thermal comfort.

Appraisal of Thermal Comfort in Non-Air-conditioned and Air-conditioned Railway Pantry Car Kitchens

This study details the consequences of a thermal comfort survey conducted in N-AC “Non-Airconditioned” and AC “Airconditioned” pantry car kitchens in Indian Railways. The research was carried out on 6 railway pantry car kitchens in which 29 chefs participated. Field measurement and subjective evaluation techniques performed in this study during the working period of chefs. The aim of the present research to compare N-AC and AC railway pantry car kitchen. While the objective of the study to determine the thermal comfort parameters “air temperature, mean radiant temperature, relative humidity and air velocity” of both pantry car kitchens and examine the subjective responses; and to evaluate the thermal comfort of both pantry car kitchens using the PMV “Predicted Mean Vote” and PPD “Predicted Percent Dissatisfied” indices and compare them with actual sensation votes. A result of this study revealed that all thermal comfort parameters do not comply with the recommended ASHRAE 55 Standard in both pantry car kitchens. There is no considerable difference between both pantry car kitchen based on the subjective assessment during the working period and all the chefs' votes were found to be outside the range of the ASHRAE 55 central three categories (-1, 0, +1) votes. Which indicates that the chefs are not satisfied with the current environment. While for N-AC pantry car, PMV and PPD value estimated were 3.10 and 99% respectively, with hot thermal sensation. Similarly, for AC pantry car, PMV and PPD value estimated were 2.21 and 85% respectively, with warm thermal sensation. The estimated values of PMV and PPD do not follow the ASHRAE-55 2017 and ISO 7730 standard. Therefore, PMV indices are not directly applicable for thermal comfort application in a pantry car kitchen environment due to high temperature. In both the pantry car kitchen, there is no difference between predicted and actual sensation votes. In further establish the other method and technique to identify the comfort temperature for better workmanship of chefs in a pantry car kitchen.

Perception of thermal comfort in outdoor public spaces in the medium-sized city of Chillán, Chile, during a warm summer

The study of thermal comfort in Latin American cities has been gaining great relevance for urban environmental planning. Some studies have evaluated the relationship between environmental and perceived comfort; however, the causes and social determinants of the different perceptions of the population have not been explored. The perception of thermal comfort in public spaces in the city of Chillán (Chile), which has an inland Mediterranean climate, is discussed in this context. First, we measured the environmental thermal comfort, adapting the Actual Sensation Vote index. A survey of 362 users of the five selected public spaces was carried out between 29 January and 01 February 2016 to obtain perceived comfort and relate it to the individual climatic history, use of public space and place of residence in the city. The results show that perceived thermal discomfort dominates over comfort on summer days; however, those users who visit public spaces for recreational purposes feel more comfortable, as well as those living in low socioeconomic status (SES) neighborhoods. On the other hand, users living in areas with higher socioeconomic status, have higher expectations regarding thermal environmental conditions.

Effects of microclimate and human parameters on outdoor thermal sensation in the high-density tropical context of Dhaka

A thermal comfort questionnaire survey was carried out in the high-density, tropical city Dhaka. Comfort responses from over 1300 subjects were collected at six different sites, alongside meteorological parameters. The effect of personal and psychological parameters was examined in order to develop predictive models. Personal parameters included gender, age, activity, profession-type (indoor or outdoor-based), exposure to air-conditioned space and sweat-levels. Psychological parameters, such as ‘the reason for visiting the place’ and ‘next destination is air-conditioned’, had statistically significant effects on thermal sensation. Other parameters, such as ‘body type’, ‘body exposure to sun’, ‘time living in Dhaka’, ‘travelling in last_30 min’, and ‘hot food’ did not have any significant impact. Respondents’ humidity, wind speed and solar radiation sensation had profound impacts and people were found willing to adjust to the thermal situations with adaptive behaviour. Based on actual sensation votes from the survey, empirical models are developed to predict outdoor thermal sensation in the case study areas. Ordinal linear regression techniques are applied for predicting thermal sensation by considering meteorological and personal conditions of the field survey. The inclusion of personal and weather opinion factors produced an improvement in models based on meteorological factors. The models were compared with the actual thermal sensation using the cross-tabulation technique. The predictivity of the three models (meteorological, thermos-physiological and combined parameter) as expressed by the gamma coefficient were 0.575, 0.636 and 0.727, respectively. In all three models, better predictability was observed in the ‘Slightly Warm’ (71% in meteorological model) and ‘Hot’ (64.9% in combined parameter model) categories—the most important ones in a hot-humid climate.

Seasonal differences of subjective thermal sensation and neutral temperature in an outdoor shaded space in Tehran, Iran

Outdoor thermal comfort influences the outdoor activities, social interactions, tourism, health and wellbeing, or even mortality. Despite the great interest in outdoor thermal comfort, few studies were conducted in arid climates. This study investigated the seasonal differences of outdoor thermal sensation in Tehran (BWk climate), based on 1008 interviews. Also the relationship between three commonly used thermal comfort indices (including UTCI, PET, and PMV) and interviewees’ thermal sensation were studied and neutral temperature and neutral range were identified in different seasons. The surveys were conducted on 79 days, periodically, in the four seasons, using microclimatic monitoring as well as subjective interviews. Two analysis approaches (mean/median, and TSVlinear = 0 methods) were applied to show the seasonal differences in neutral temperature. It was found that neutral temperatures, neutral range, and thermal sensations were significantly different, especially between summer, winter, and the two shoulder seasons. Although the two different analysis approaches resulted in noticeably different neutral temperatures, especially in the winter, revealing the importance of the developing standard analysis techniques. The results also indicated that PMV overestimated the thermal sensation by the factors of 1.6–1.8, while PET and UTCI had stronger correlation with actual sensation votes. At the end, an empirical model was proposed for predicting thermal sensation in Tehran. The outcomes of this study showed that to design a sustainable and appropriate urban space in this climate, priorities should be given to the winter and summer seasons.

Thermal comfort and urban canyons morphology in coastal temperate climate, Concepción, Chile

This paper aims to bridge the gap between urban climatology and urban design in coastal temperate climate cities of developing countries. This research studies the thermal comfort in urban canyons located in the city of Concepción, Chile, using a multidisciplinary approach that combines morphological, climatic and perceptual factors. First, the urban morphology indicators are constructed, such as the sky view factor and the shadow factor of buildings. Second, to determine the environmental thermal comfort, the Actual Sensation Vote (ASV) method is used by conducting measurements in 27 control points in 9 urban canyons. Third, 301 surveys were conducted to pedestrians in urban canyons during January 2014. All the data is processed and correlated to determine how the urban canyons morphology modifies the dominant climate in terms of physical and perceived thermal comfort. The results show that the diagonal canyon has one of the best indicators of environmental and perceived thermal comfort. On the other hand, the semi-covered canyon with high pedestrian affluence has the worst comfort values. Overall, the metropolitan center of Concepción is more comfortable than uncomfortable in the summer season.

Milder form of heat-related symptoms and thermal sensation: a study in a Mediterranean climate.

Mild heat-related health effects and their potential association with meteorological and personal parameters in relation to subjective and objective thermal sensation were investigated. Micrometeorological measurements and questionnaire surveys were conducted in an urban Mediterranean environment during a warm, cool, and a transitional season. The participants were asked to indicate their thermal sensation based on a seven-point scale and report whether they were experiencing any of the following symptoms: headache, dizziness, breathing difficulties, and exhaustion. Two thermal indices, Actual Sensation Vote (ASV) and Universal Thermal Climate Index (UTCI), were estimated in order to obtain an objective measure of individuals' thermal sensation. Binary logistic regression was applied to identify risk parameters while cluster analysis was used to determine thresholds of air temperature, ASV and UTCI related to health effects. Exhaustion was the most frequent symptom reported by the interviewees. Females and smokers were more likely to report heat-related symptoms than males and nonsmokers. Based on cluster analysis, 35°C could be a cutoff point for the manifestation of heat-related symptoms during summer. The threshold for ASV was 0.85 corresponding to "warm" thermal sensation and for UTCI was about 30.85°C corresponding to "moderate heat stress" according to the Mediterranean assessment scale.

Empirical calibration of thermal indices in an urban outdoor Mediterranean environment

Thermal indices are important for assessing human thermal perception and are widely used as indicators of heat strain as well as for designing, tourism and forecast purposes. This research focuses on thermal sensation scales calibration of a large number of thermal indices in order to be applied with greater success in outdoor urban environments in Mediterranean climatic zones. Field questionnaire surveys were carried out during three different seasons monitoring microclimatic variables and subjective characteristics while interviewees were asked to indicate their thermal sensation based on a seven point thermal sensation scale. Three calibration methods, linear and cubic regression as well as probit analysis, were applied and compared based on three statistical criteria. Indices' predictions according to the calibrated scales were evaluated aiming to designate the one that best simulates thermal sensation. Probit analysis calibrated indices assessment scales more adequately compared to linear or cubic regression. Overall Actual Sensation Vote (ASV), Subjective Temperature Index (STI) and Universal Thermal Climate Index (UTCI) based on the calibrated scales showed the best predictability of thermal sensation vote compared to all the indices studied.

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.

Thermal comfort in naturally ventilated apartments in summer: Findings from a field study in Hyderabad, India

There is little thermal comfort research in residential environments reported from India. Energy consumption in Indian residential buildings is one of the highest, increasing at a phenomenal rate. Indian standards advocate two narrow ranges of temperatures for all building and climate types. In this context, a field study in summer and monsoon was conducted following Class-II protocols, for three months in 2008, in naturally ventilated apartment buildings in Hyderabad. Over a 100 subjects involved, giving 3962 datasets. In May, most of the subjects were uncomfortable, preferring a temperature on the cooler side of the neutrality, despite accepting their thermal environments. Thermal sensation, preference and acceptance improved in June and July as temperature receded. Humidity did not affect comfort sensation much, as summer was hot and dry. Conversely, increase in humidity adversely affected the thermal comfort in June. Adaptive use of controls resulted in moderate air movement indoors, adequate for sweat evaporation most of the time. The subjects used traditional ensembles and slowed down their activities adaptively to restore thermal comfort. Clothing adaptation was found to be impeded by many socio-cultural and economic aspects. The comfort band (voting within −1 and +1) based on the regression analysis was found to be 26–32.45 °C with the neutral temperature at 29.23 °C. This is way above the limits (23–26 °C) set by Indian standards. The PMV was always found to be higher than the actual sensation vote. These findings have far reaching energy implications in a developing country like India.