This paper examines the outdoor thermal comfort in the Mediterranean area. A transversal field survey has been conducted in Rome and, during an entire year, over 1000 questionnaires were filled and ...combined with micrometeorological measurements. In the first part of the questionnaire, the interviewees answered to personal questions, whereas in the second they evaluated their thermal perception and preference through the ASHRAE 7-point scale and the McIntyre scale respectively. Regression lines were obtained by elaborating the thermal perception votes and determining a PET (Physiological Equivalent Temperature) value for each questionnaire. These regression lines gave the possibility to calculate the neutral PET values: 26.9 °C for the hot season and 24.9 °C for the cold one. Differently, the votes concerning the thermal preference were related to the corresponding PET values through a logistic curve model with the probit function: for the hot season a preferred PET value of 24.8 °C was calculated, whereas for the cold season 22.5 °C. This shows the influence of thermal adaptation. Then since the thermal comfort interval should correspond to the range −0.5÷0.5 of the ASHRAE 7-point scale, a PET comfort range of 21.1÷29.2 °C was obtained. Finally two indexes were determined: the first, called MOCI (Mediterranean Outdoor Comfort Index), is based on the ASHRAE 7-point scale and predicts the mean value of the votes Mediterranean people might give to judge the thermal qualities of an environment; the second is the adaptation of the PPD (Predicted Percentage of Dissatisfied) relation to the Mediterranean population.
•A transversal field survey (over 1000 questionnaires) was performed during a whole year.•The neutral PET values are 26.9 and 24.9 °C respectively for hot and cool seasons.•The preferred PET values are 24.8 and 22.5 °C respectively for hot and cool seasons.•The PET comfort range is defined as being 21.1÷29.2 °C.•A new empirical index (MOCI) is proposed and the PPD relation readapted.
In practice, building heating, ventilation, and air conditioning (HVAC) systems are essentially set at nominal levels according to industry guidelines. However, several studies have demonstrated that ...this conventional practice is unlikely to meet the thermal requirements of occupants in a single or multi-occupancy space due to occupants' diverse preferences, activities and needs. To improve occupants' thermal comfort, this study develops and tests a smartphone application framework which is capable of dynamically determining the optimum room conditioning mode (mechanical conditioning or natural ventilation) and HVAC settings (thermostat setpoint) in single and multi-occupancy spaces. The “personalized” HVAC control framework integrates environment data (obtained from sensors) with human physiological and behavioral data (obtained from wearable devices, polling apps) in a smartphone application we developed for human-building interaction. In the operation phase, occupants' thermal preferences are continuously predicted using the personalized comfort models, developed from the training data through the Random Forest classifier, when determining the optimum HVAC control strategies. Two case studies are conducted to demonstrate the capabilities of the developed framework to improve thermal comfort in single and multi-occupancy spaces.
•A personalized HVAC control framework which integrates environment and human data is proposed.•Human physiological and behavioral data can significantly improve the accuracy of predicting thermal preferences.•Occupants' diverse thermal preferences should be considered in the HVAC control strategy.•Optimum room conditioning mode and setpoint can be determined by evaluating the identified human and environment factors.
Nursing homes are designed and operated to meet general thermal specifications outlined by existing standards. This paper presents adaptive thermal comfort models for nursing homes based on the field ...survey administered in 100 common rooms of five nursing homes in the Mediterranean climate. The survey included simultaneous measurements of outdoor and indoor environmental parameters and an assessment of the occupants’ thermal comfort sensations using questionnaires. In total, 1,921 subjective questionnaires were obtained. The analysis focused on: Building Operation Mode (naturally ventilated and air-conditioned mode (cooling and heating)); and type of occupant (residents and non-residents (caregivers and therapists)). In naturally ventilated rooms residents were found to be more adaptive than what EN and ASHRAE 55:2020 standards propose (Tc (naturally ventilated) = 0.26 Trm + 18.83 (R2 = 0.81)). Residents in air-conditioned rooms were found to be less sensitive to outdoor conditions (Tc (air-conditioned) = 0.16Trm + 20.41 (R2 = 0,91)) than in naturally ventilated rooms. Both adaptive thermal models fall in limits set by these standards but in the lower acceptable levels. These adaptive thermal comfort models for nursing homes will allow extending the use of natural ventilation and the adoption of setpoint temperatures when air-conditioning is needed with the consequent reduction of heating and cooling use.
The thermal environment outdoors affects human comfort and health. Mental and physical performance is reduced at high levels of air temperature being a problem especially in tropical climates. This ...paper deals with human comfort in the warm-humid city of Guayaquil, Ecuador. The main aim was to examine the influence of urban micrometeorological conditions on people’s subjective thermal perception and to compare it with two thermal comfort indices: the physiologically equivalent temperature (PET) and the standard effective temperature (SET*). The outdoor thermal comfort was assessed through micrometeorological measurements of air temperature, humidity, mean radiant temperature and wind speed together with a questionnaire survey consisting of 544 interviews conducted in five public places of the city during both the dry and rainy seasons. The neutral and preferred values as well as the upper comfort limits of PET and SET* were determined. For both indices, the neutral values and upper thermal comfort limits were lower during the rainy season, whereas the preferred values were higher during the rainy season. Regardless of season, the neutral values of PET and SET* are above the theoretical neutral value of each index. The results show that local people accept thermal conditions which are above acceptable comfort limits in temperate climates and that the subjective thermal perception varies within a wide range. It is clear, however, that the majority of the people in Guayaquil experience the outdoor thermal environment during daytime as too warm, and therefore, it is important to promote an urban design which creates shade and ventilation.
Thermal comfort indices are vital tools when assessing outdoor thermal comfort in hot and arid environments. Selecting a representative thermal comfort index for outdoor environments is challenging. ...This paper presents a comparative study of the suitability of seven different thermal comfort indices, namely PMV, discomfort index, cooling power index, Humidex, WBGT, SET, and UTCI in assessing outdoor thermal comfort. The thermal comfort indices were compared to the thermal sensation vote (TSV) obtained from a thermal comfort questionnaire of spectators seated in a semi-open air-conditioned stadium. Seated in six different zones, a total of 532 spectators participated in an online questionnaire. The results of the survey indicated high levels of climate acceptability, with small variations among the stadium zones and between genders. Almost 40% of the spectators reported feeling ‘‘cool’‘, while 28% of the spectators were feeling ‘‘slightly cool’’ and 21% reported a ‘‘neutral’’ thermal perception. Hence, CFD simulations were used to predict the values of the seven thermal comfort indices. The thermal comfort indices' values, obtained from the CFD simulations, were compared to their counterparts obtained from the questionnaire. The WBGT index showed good agreement to the actual questionnaire data with an average difference of 8.8%. The other six indices yielded an average range of difference of (15%–46%). The WBGT index deemed the most suitable to assess outdoor thermal comfort for hot and arid regions, followed by the UTCI and the SET indices, with average differences of 14% and 15%, respectively. The CPI index deemed not suitable for hot and arid regions compared to other indices.
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Outdoor thermal comfort could significantly affect the usage and success of urban places. Accordingly, it is recommended to be considered in both urban design and planning projects. Urbanisation has ...been recognised as a major factor in elevated daily temperature values in Australia. This study aims to investigate the past and current position of outdoor thermal comfort studies in the Australian context. A critical review is conducted to examine the quality of thermal comfort assessment in Australia's cities. Twenty-five studies were reviewed to give a precise overview of past thermal comfort studies. The review scrutinises the focus of research, methodologies applied, data collection methods and results. This review helps main stakeholders in urban development better understand the evolution of outdoor thermal comfort with respect to liveability. In this line, where possible, the shortcomings are identified, certain solutions are provided and the need for further research is highlighted. In particular, future studies are necessary to cover missing geographical regions and ethnicities that are not considered in the existing literature. Furthermore, more psychological thermal adaptation studies are necessary, especially in transient thermal conditions. Qualitative analysis is also recommended to be incorporated in further studies in addition to considering the perceived environmental quality. The study serves as a reference to researchers, urban designers and planners to enhance their knowledge for achieving outdoor thermal comfort and understanding the gaps that need to be addressed in further studies.
•Intra-urban difference in outdoor thermal comfort depends on site characteristics.•Further studies required to cover missing geographical regions and ethnicities.•Psychological thermal adaptation studies needed, including transient conditions.•Qualitative approach can evaluate urban space types and thermal adaptation.•Perceived environmental quality can be considered to assess outdoor thermal comfort.
The predicted mean vote (PMV) and its several revised models are widely used for the prediction of thermal comfort. This study aims to assess their performances using the Chinese Thermal Comfort ...Database (N = 41977). In air-conditioned buildings, the PMV prediction accuracy (P) and the mean absolute error (MAE) are 41.2 % and 0.86, respectively, which is better than the performance in free-running buildings (P = 31.9 %, MAE = 1.09). The performance of the PMV model is also tested under different HVAC modes, climate zones, and building types. The prediction accuracy varies but does not exceed 60 % for all subset cases. Three typical revised models (ePMV, nPMV and aPMV) considering thermal adaptation show better accuracy than the PMV, but the improvements are still limited and do not exceed 5 %. It appears that the PMV and revised models are reliable under thermal neutrality conditions, while their accuracy decreased towards the ends of the thermal sensation scale, especially on the cooler side. For further improvement of the prediction performance, it may be necessary to consider the effect of thermal adaptation in parallel with other approaches, such as revising the PMV core structure and considering individual differences.
Researchers have conducted extensive research on the thermal environments of rural houses worldwide. The greatest number of studies on thermal comfort in rural areas have been conducted in China. ...However, no studies have reviewed or summarised the literature. This paper summarises the literature from three perspectives: climate zones, thermal comfort approach, and other factors (wind speed, humidity, and building construction) that influence thermal comfort. The research commenced by categorising and examining all relevant papers based on climatic comfort and thermal comfort approaches to find commonalities and differences. The limits of existing thermal comfort standards were then inspected. Finally, suggestions for further research on rural thermal comfort were provided. Our conclusion was that thermal comfort temperature is influenced by various factors. Further research on the thermal comfort of older adults is required, especially in rural areas. The Adaptive Thermal Comfort model was more suitable for rural housing than the Rational Thermal Comfort model. Large-scale studies on thermal comfort in rural houses are required to establish specific thermal comfort standards. Wind speed and humidity are two aspects that require further research in rural thermal comfort.
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•This is the first paper that examines past research on thermal comfort field investigation in rural houses.•Summarising the thermally neutral temperature and thermal comfortable temperatures of rural residents across different in China.•Comparing the results of applying different thermal comfort approaches to rural dwellings.
The factory area is an important part of the city. Its environment is relatively simple, mainly with large plant buildings and less vegetation, which is easy to form an extreme outdoor thermal ...environment. However, few studies have focused on how these changes affect outdoor thermal comfort in factory areas. In this study, through field meteorological measurements and questionnaire surveys, outdoor thermal comfort of different built environments in two factory areas in Haining, China, located in the hot summer and cold winter zone, was studied in winter. Combined with thermal comfort indices Physiological Equivalent Temperature (PET) and Universal Thermal Climate Index (UTCI), 12 observation sites in factory areas were analyzed to establish the outdoor thermal benchmark suitable for the factory area. The results show that: (1) Thermal comfort was strongly related to thermal sensation. (2) Air temperature and globe temperature were two primary factors affecting workers' thermal sensations. In addition, thermal sensation was negatively correlated with wind speed and relative humidity. (3) The built environment had a significant influence on human thermal sensation and thermal comfort; sky view factor was an important morphology parameter that affected outdoor thermal sensation, and the outdoor thermal sensation improved as it increases. (4) Neutral temperatures of PET and UTCI were 14.3 °C and 15.8 °C; neutral PET range and neutral UTCI range were 10.7–17.8 °C and 12.2–19.4 °C, respectively. These findings could serve as theoretical baselines and guidelines for factory area design.
•Outdoor thermal comfort is investigated in factory areas during winter in Haining, China.•Ta and Tg are the primary meteorological parameters affecting workers' thermal sensation.•Outdoor human thermal comfort varies with built environments in factory areas.•Neutral PET range and neutral UTCI range are 10.7–17.8 °C and 12.2–19.4 °C.•Neutral PET/UTCI and neutral PET/UTCI range depend on the context and characteristics of study areas.
Urban residents suffer more from heat stress, compared to people living in rural areas, due to the urban heat island (UHI) effect. Mitigation of UHI is thus essential to improving human thermal ...comfort and living environment in urban residential areas. However, little attention has been paid to the integrated effect of UHI mitigation strategies on human thermal comfort, which is influenced by the combination of temperature, humidity, wind, and radiation. This study evaluates the effectiveness of two promising UHI mitigation strategies, cool and green roofs, in improving human thermal comfort during a heatwave in Berlin. Human thermal comfort is represented by the Universal Thermal Climate Index (UTCI), calculated by combining the Weather Research and Forecasting model coupled with the Urban Canopy Model (WRF/UCM) with the RayMan model. The results show that cool roofs outperform green roofs in reducing urban temperatures, especially at night. Besides temperature reduction, both strategies show lower wind speed, lower mean radiant temperature, and higher relative humidity. These combined effects lead to a city-scale decrease in UTCI. Cool roofs reduce more UTCI than green roofs, although they both shorten the duration of strong heat stress from 7 h d−1 to 5 h d−1. A higher albedo and irrigation can strengthen the cooling effect of cool and green roofs, respectively. Our study can deepen the understanding of the mechanism of natural infrastructure in improving human thermal comfort, providing scientific guidance for future city management.
•We evaluated the effectiveness of cool and green roofs in improving human thermal comfort during a heatwave in Berlin.•Cool roofs outperform green roofs in mitigating urban heat island and improving human thermal comfort.•Both strategies shorten the duration of strong heat stress from 7 h d−1 to 5 h d−1.
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