Investigation Of Thermal Comfort Research Articles

Investigation of thermal comfort of room air conditioner during heating season

The main factors affecting field thermal comfort of convective terminals during the heating season have been widely studied in recent years. Since previous studies were conducted separately, this investigation aimed to analyze the thermal comfort under typical settings and integrated control strategies. A questionnaire, based on a field operation, was conducted to compare and find the main characteristics of different terminals. The contradiction of draft and vertical temperature difference and the continuous/intermittent feature control were the key factors investigated. The indoor environment distribution under different conditions was measured in laboratory cabins based on the different settings and control strategies of convective terminals. The thermal sensation vote (TSV) and thermal comfort vote (TCV) were conducted in an artificial chamber to show the characteristics of an indoor environment under different conditions. The results showed that people were more tolerant of drafting than vertical temperature differences (the TCV score decreased from 0.44 to 1.42 with different temperature non-uniformity and airspeed). In particular, the subjects’ perceived control significantly reduced the risk of discomfort. In addition, there was no significant difference between the different control strategies, including continuous operation and intermittent operation, except for a long-term control shutdown. The TCV result was 0.48 in the on-off control with a 5-min shutdown, showing statistical significance in paired-sample t-tests (p < 0.05).

Investigation of thermal comfort on innovative personalized ventilation systems for aircraft cabins: A numerical study with computational fluid dynamics

Airliner passengers are more and demanding in terms of thermal comfort. But it is not yet easy for crew to control the environment control system (ECS) that satisfies the thermal comfort for most travelers due to a number of reasons. It is, therefore, essential to develop the existing design of air circulation system for aircraft cabins. This work proposed six innovative personalized ventilation systems (PVSs) that would maintain thermal comfort to improve the cabin micro-environment. This study first validated a Computational Fluid Dynamics (CFD) program with the experimental data of airflow and air temperature from an environmental chamber. Then the validated CFD program was used to calculate the air velocity, air temperature, relative humidity (RH) and examined the thermal comfort in a section of Boeing 767 aircraft cabin with the six innovative PVSs. By comparing the six PVSs in terms of relative humidity, velocity, temperature, predicted mean vote (PMV), predicted percentage dissatisfaction (PPD) and age of air (AoA), this study found that the proposed systems provided an acceptable thermal environment aircraft cabin. The personal outlets configuration at both sides of the passenger head (PVS-1) was the best; it can improve the RH by 12% without the risk of air drafts, and it also has a standard PMV (0.2) and PPD (<15%) range.

Investigation of pregnant women thermal comfort in the waiting area of the hospital in South China, Guangzhou

Indoor thermal environment significantly affects human health and comfort. Although several studies have investigated this aspect in numerous buildings, a gap exists with regard to the hospital waiting areas and the thermal comfort of pregnant women. Therefore, this study assessed the ambient conditions in the waiting areas of obstetric departments in four Guangzhou hospitals during summer and winter and conducted a questionnaire survey on pregnant women and males & non-pregnant female patients in the waiting areas to analyze the differences in their thermal sensation. A total of 2594 questionnaire responses were collected during the survey period, including 1477 and 1117 responses during summer and winter, respectively. Further, the predicted mean vote (PMV) model was applied to evaluate the thermal comfort and differences in the thermal sensation between pregnant women and escorts. The results indicated that the PMV model could not accurately predict the thermal comfort of the subjects and overestimated their thermal sensation. Additionally, the acceptable operative temperature ranges in the obstetric waiting areas were 23.8–28.6 °C and 18.5–23.5 °C, and acceptable standard effective temperature ranges were 21.0–27.9 °C and 19.0–25.8 °C during summer and winter, respectively. Further, the neutral temperature of pregnant women was lower than that of the males & non-pregnant female patients. The results of this study can guide the indoor thermal environments in the hospitals for the improved comfort of pregnant women, which in turn, will benefit their health as well as that of their babies.

Experimental investigation of transient thermal comfort for the indoor vegetation

ABSTRACT Present work focuses on sustainable energy-based technique for achieving the required thermal comfort inside a greenhouse unit. A region of definite volume is built, and the plants are placed inside it. Evaporative cooling setup consists of cooling pads, water spray unit and a blower are designed to regulate the ventilation inside the space. Experiments are conducted for a fixed peak time and changing the flow rate of air. Results indicated that the maximum temperature drop, and relative humidity drop values are observed to be 7.7°C and 22%. It is seen that optimum performance could be obtained for an airflow rate of 12 m/s and the corresponding Coefficient of Performance (COP), evaporation rate and cooling efficiency values are 2.4787, 0.1181 g/s and 60.05%, respectively.

Modeling and Experimental Investigation of Thermal Comfort and Energy Consumption in a Battery Electric Bus

In battery electric buses (e-buses), the substantial energy consumption of the heating, ventilation, and air conditioning (HVAC) system can cause significant reductions of the available travel range. Additionally, HVAC systems are often operated at higher levels than what required for the thermal comfort of the passengers. Therefore, this paper proposes a method to experimentally investigate the influence of the HVAC system on the energy consumption and thermal comfort in a 12m e-bus. An appropriate thermal comfort model is identified and the required climatic input parameters are selected and measured with self-developed sensor stations. The energy consumption of the e-bus, the state of charge (SoC) of the battery and the available travel range are measured by an embedded data logger. Climatic measurements are then performed with heating on and off on a Berlin bus line in winter conditions. The results show that the energy consumption of the e-bus is increased by a factor of 1.9 with heating on, while both the SoC and travel range are reduced accordingly. Comparing the thermal comfort with heating on and off, a decrease from “comfortable” to “slightly uncomfortable but acceptable” is observed.

Thermal Comfort Investigation Based Design Considerations for the Tropical Studio Type Classroom

Thermal Comfort Investigation Based Design Considerations for the Tropical Studio Type Classroom

Numerical investigation of indoor thermal comfort and air quality for a multi-purpose hall with various shading and glazing ratios

This research assesses the effect of outdoor parameters, including solar radiation and shading and glazing configurations, on indoor thermal comfort and air quality in multi-purpose halls in Auckland, New Zealand. The Design of Experiment (DOE) method by using CFD simulation has been utilized for this study. Input parameters are windows length, overhang angle, and overhang length, while output parameters are occupant zone average temperature and mass fraction. The temperature sensitivity to the glazing parameter changes with time, and its maximum occurs at 11:00 and is 95%, while for the shading ones happen at 9:00 and is 50%. The peak of CO2 mass fraction sensitivity to glazing and shading parameters coincides at 9:00 and is 90% and 80, respectively. The variation rate of temperature and CO2 mass fraction VS. Glazing parameter (W.L) is approximately positive on the summer day. However, it has a nonlinear and complex behavior, while the shading one has a sinusoidal behavior. On the other hand, on the winter day, the temperature variation rate is almost linear regarding this factor. The result shows that appropriate shading and glazing situation for each time is different, and for reaching the best comfort, dynamic shading and glazing should be designed. Comfort criteria sensitivity within the school is highly dependent on glazing parameters compared with shading configurations. The temperature can be controlled up to 3 and 1.6 degrees on the summer and winter day, respectively. Finally, it can be concluded that glazing tools can compensate for a significant amount of required heating in the winter days, and shading devices and openings can control the air quality in the school buildings with neglectable overheating.

Investigation of thermal comfort in sleeping environment and its association with sleep quality

Thermal environment can greatly influence one's sleep quality, yet research into thermal satisfaction and sleep quality is lacking. This study investigates the thermal environment, thermal sensation, satisfaction and sleep quality of university students residing in dormitory in Hong Kong in winter. Based on subjective questionnaire and environmental measurement, it was found that under the same thermal condition, females selected a bedding system with higher total thermal resistance than males. Self-assessed overall sleep quality was associated with mid-sleep/early awakenings, refreshment and duration of sleep, and sleep quality was largely influenced by thermal comfort and satisfaction. Thermally satisfied subjects and those with neutral thermal sensation had significantly better sleep quality. Thermal satisfaction and sleep quality toward hot and cold environments were also different. Existing sleeping thermal comfort models failed to predict accurately the thermal sensation in sleeping state, suggesting a need for the development of better prediction model for sleeping person.

Numerical Investigation of Airflow Patterns and Thermal Comfort in a Bus Cabin

Numerical Investigation of Airflow Patterns and Thermal Comfort in a Bus Cabin

Investigation of Thermal Sensation in a Railway Vehicle during Cooling Period

The paper presents an investigation of local thermal comfort of passengers in a railway vehicle. The railway vehicle model includes five different parts called modules, and each module had different properties such as passenger capacity and seating arrangement. A virtual manikin model was developed and added to the numerical model which includes convection and radiation heat transfer between the human body and the environment. The numerical simulation was conducted according to the EN 14750-1 standard describing the thermal comfort conditions for different climatic zones. Two different cases were performed for steady-state conditions. Meanwhile, measurements were taken in a railway vehicle cabin to validate the numerical simulation, and the numerical results were in good agreement with the experimental data. It is observed that the local heat transfer characteristics of the human body have significant importance for the design of an effective heating, ventilation, and air conditioning (HVAC) system because each module had different heat transfer and air flow characteristics. It is also shown that the thermal sensation (TSENS) index helps railway vehicle HVAC researchers to determine the reasons for discomfort zones of each occupant. Another important result is that using a single air flow channel did not meet the thermal comfort demands of all passengers in this railway vehicle. Therefore, multiple air flow channel design configurations should be considered and developed for these vehicles. Local thermal comfort models allow HVAC systems to achieve better comfort conditions with energy saving. The numerical model can be used for effective module design, including seating arrangements, to achieve better thermal comfort conditions.

An investigation of thermal comfort, IAQ, and energy saving in UFAD systems using a combination of Taguchi optimization algorithm and CFD

ABSTRACT The present study investigates underfloor air distribution (UFAD) systems by using the combination of computational fluid dynamics (CFD) and the Taguchi optimization algorithm. A multi-objective optimization approach is used to analyze the efficiency of UFAD systems from the viewpoints of thermal comfort, indoor air quality (IAQ), and energy consumption. The supply air temperature, the air change rate per hour (ACH), and the height of the return air vent factors are considered in order to achieve the optimum operating condition. First, numerical validation has been done for an office room model, and then optimization has been performed for this space. The optimization results state that setting the supply air temperature and ACH at 19°C and 4.0, respectively, and placing the return air vent at the height of 1.6 m would lead to the optimum state. The CFD simulation results for this condition show that the thermal comfort in the occupied zone and the desirable IAQ in the breathing zone are established, corresponding to the predicted mean vote (PMV) and mean age of air (MAA) values equal to 0.13 and 640 s, respectively. Furthermore, energy consumption has a considerable reduction of 21.5%, compared to the conventional mixing ventilation (MV) systems.

Investigation of Thermal Comfort for Bus Passengers During a Cooling Test Inside a Climatic Chamber

In this current work, thermal comfort for a cooling process inside a bus was described in a combined theoretical and experimental form. The bus was heated to 40 for 7 hours within climatic chamber and AC unit was turned on at the beginning of the test. Temperatures, humidity of air and air velocities were measured at certain points to observe effects of ambient conditions on passengers’ thermal comfort and physiology. Human body was assumed to be one complete piece which is composed of mainly core and skin compartments. Transient Energy Balance Model by Gagge was used for calculation of changes in thermal conditions. Transient heat and mass transfer between bus interior environment and passenger bodies during cooling period were calculated by a mathematical model. Effects of fast transient conditions on either sensible or latent heat transfer from body, temperatures of core and skin, thermal discomfort and thermal sensation which are all factors for human ergonomics were investigated in detail. The aim in this study is to describe a testing and thermal comfort calculation methodology for assessment of thermal comfort of a bus AC system’s cooling performance.

Investigation of thermal comfort and behavioral adjustments of older people in residential environments in Beijing

Aged population is growing rapidly and aging in place is the major endowment pattern for older people. This study focused on the thermal living environments and thermal comfort of older people in their own homes. Special attention was paid to their behavioral adjustment characteristics. The longitudinal investigation was conducted from March 2018 to March 2019 in a residential community in Beijing, China, and the participants involved 5 households with 10 older respondents. The investigation included a yearlong continuous environmental measurement, behavioral monitoring, and a monthly collection of subjective evaluations. Face-to-face interviews on behavioral adjustments were also conducted with 102 older respondents in different communities in Beijing. The field investigation involved the observation of seasonal variation in the indoor environments and subjective evaluations. The prediction accuracy of the predicted mean vote (PMV) model was found to be inconsistent for thermal sensations of older people between the cold side and hot side. With regard to the behavioral adjustments of older people, this study described the effect of the outdoor temperature on window opening behavior and air conditioner use, and the effect of indoor temperature on clothing behavior. The preference for the adjustment methods were studied, and the personal characteristics of older people (including sex, age, educational background, and time spent at home) were found to influence their preference for different methods. The differences in behavioral adjustments between older and non-older people and between older people in different climate zones were discussed by comparing this study to previous field studies.

Thermal comfort and Indoor Air Quality assessment in university classrooms

Investigation of thermal comfort in various types of buildings is a rather intense research activity by recent years. Besides thermal comfort, the Indoor Air Quality (IAQ) is also important for the sensation of humans in indoor environments, as well as for their health. In the proposed work, a systematic measurement campaign in university classrooms in the Educational School of the University of Western Macedonia, Florina, Greece, is presented; the campaign was performed through winter time, noting that the University lies on the coldest thermal zone on a country level. Measurements include thermal comfort parameters, as well as IAQ ones, namely volatile organic compounds (VOCs), aldehydes and NO2concentration.As far as thermal comfort is concerned, Fanger’s thermal comfort indices are calculated, on the basis of the measured data; a comparison is made through the support of questionnaires investigating the actual thermal comfort level of the students while being in the classrooms, aiming at providing information on an adaptive sensation level. In terms of air quality, measurements are made both indoors and outdoors, allowing the determination of indoor/outdoor correlations.

Investigation of human thermal comfort and improvement in public places adapted to a hot climate in Iraq

This study focuses on improving the thermal comfort in Mosques in Iraq. Omar bin Abdul Aziz Mosque in Baghdad is taken as a case study. In general, the weather in Baghdad is hot- dry climate during the summer. the study was conducted at the time of noon prayer on Friday where the maximum number of people can be obtained inside the Mosque about 500 worshipers and severe environmental conditions. Numerical methods (CFD) are used for the simulation utilizing the package of ANSYS (FLUENT V. 18). As the results depending on the number of elements, 4 millions elements are used for dividing the physical domain. Thermal comfort was assessed by finding the values of the predicted mean vote (PMV), predicted percentage of dissatisfied (PPD), and ASHRAE standard-55. The adaptive redistribution of the air conditioning device strategy at five cases is used to obtain the best thermal comfort. Moreover, changing the angle of air intake of space by changing the angle inclination of the access blade at three different angles of 0o, 7.5o and 15o degree, and studying its effect on the thermal comfort in breathing level. The four case is the best in terms of thermal comfort when the angle of intake air at 0o.when the PMV was 0.35 and PPD is 7.5, which is lower than the original state. The improving percentage of PPD is 10 % and PMV 14 %.

Daylight affects human thermal perception

Understanding the factors that affect human thermal responses is necessary to properly design and operate low-energy buildings. It has been suggested that factors not related to the thermal environment can affect thermal responses of occupants, but these factors have not been integrated in thermal comfort models due to a lack of knowledge of indoor factor interactions. While some studies have investigated the effect of electric light on thermal responses, no study exists on the effect of daylight. This study presents the first controlled experimental investigation on the effect of daylight quantity on thermal responses, combining three levels of daylight illuminance (low ~130 lx, medium ~600 lx, and high ~1400 lx) with three temperature levels (19, 23, 27 °C). Subjective and objective thermal responses of 84 participants were collected through subjective ratings on thermal perception and physiological measurements, respectively. Results indicate that the quantity of daylight influences the thermal perception of people specifically resulting in a cross-modal effect, with a low daylight illuminance leading to a less comfortable and less acceptable thermal environment in cold conditions and to a more comfortable one in warm conditions. No effect on their physiological responses was observed. Moreover, it is hypothesised that a warm thermal environment could be tolerated more whenever daylight is present in the room, as compared to the same thermal condition in a room lit with electric lights. Findings further the understanding of factors affecting human thermal responses and thermal adaptation processes in indoor environments and are relevant for both research and practice. The findings suggest that daylight should be considered as a factor in thermal comfort models and in all thermal comfort investigations, as well as that thermal and daylight illuminance conditions should be tuned and changed through the operation and design strategy of the building to guarantee its occupants’ thermal comfort in existing and future structures.

An Investigation of Thermal Comfort of Houses in Dry and Semi-Arid Climates of Quetta, Pakistan

In Pakistan, reinforced concrete frame houses are the most widely used and common construction technology. In a country that experiences extreme hot and cold seasons throughout the year, buildings need to be adaptable to the climate to improve the thermal comfort of the inhabitants. Therefore, the aim of this study was to improve thermal comfort in reinforced concrete frame houses using passive design and energy efficiency measures in Quetta, Pakistan. Thermal comfort of a representative house was investigated using a building performance simulation. The building model created in EnergyPlus was validated by comparing it with on-site monitored data in both summer and winter seasons. The model was calibrated using statistical methods. Then, the calibrated model was used to perform a whole year simulation in which various orientations, ventilation, passive design, and energy efficiency strategies were applied to perform parametric analysis for the improvement of thermal comfort. The best fit-to-context thermal comfort model was selected, and the potential of bioclimatic design strategies was quantified. The results indicate that by adopting passive design strategies comfort hours can be increased from 43% to 59%. The results of the study revealed many findings which could be useful for architects and building engineers to set a future direction for improvement of indoor comfort in Quetta as well as in many other areas of Balochistan Province in Pakistan.

CFD Investigation of Air Flow Patterns and Thermal Comfort in a Room with Diverse Heating Systems

Objective: The main focus in the current work is to investigate how diverse heating systems and their locations influence the indoor thermal environment in an exhaust- ventilated room. Methods: Four systems for heating the room were used in the current study, in which, heat was transferred by convection and radiation. The four systems were: wall and floor heating at low temperatures, Medium Temperature Radiator (M.T. radiator) heating and High Temperature Radiator (H.T. radiator). Computational Fluid Dynamics (CFD) simulation was used to investigate indoor temperature, vertical air temperature gradient and thermal comfort for each case. The ventilation rate was set to be 6 air changes per hour (ACH) entering the room through a vent over the window. Results: The findings from the current work were that the low temperature heating systems had better temperature distributions with lower vertical Air Temperature Differences compared to high and medium temperature radiator systems. Conclusion: The Predicted Mean Vote (PMV) and the predicted percentage of dissatisfied (PPD) based on Fanger’s model were calculated for all cases, and were found to be in the recommended ranges.

Investigation and analysis of thermal comfort in naturally ventilated secondary school classrooms in the composite climate of India

ABSTRACT India is a vast country spread across five climatic zones. The current Indian building codes specify thermal comfort standards for naturally ventilated offices only. This paper presents a year-long field study carried out during 2015–16 to investigate thermal comfort in naturally ventilated (NV) classrooms of three government residential schools located in the composite climatic zone of India. A total of 1890 data sets were collected from children and teenagers in the age group of 10–18 years. The students in naturally ventilated classrooms were found to be more adaptive than what is prescribed in the ASHRAE thermal comfort standards. Indoor operative temperatures of 28.2°C and 19.4°C were recorded as the neutral temperatures of the summer and winter seasons, respectively. The study proposes a thermal comfort range of 16°C to 33.7°C for 80% acceptability. The study also proposes an adaptive thermal comfort model for naturally ventilated secondary school classrooms in composite climatic zones. The results show that students are adapted to higher temperatures in classroom environments. The study provides a baseline for further research in developing thermal comfort standards for secondary school classrooms in India.

Experimental investigation of thermal comfort and CO2concentration in mosques: A case study in warm temperate climate of Yalova, Turkey

The strategies and techniques of heating, cooling and ventilation are different for mosques than for other types of buildings because of their large volumes, intermittent use, and hosting a great number of congregation members. We investigate potentially feasible strategies to improve thermal comfort and air quality in a representative urban mosque located in a warm temperate climate. These strategies include opening windows, turning on air conditioners, using fans, and their combinations while considering the effect of occupancy. The overall thermal sensation, draught risk, and CO2 concentration were experimentally studied during the holy month of Ramadan. In the naturally ventilated mosque, opening windows considerably improved the air quality but increased the indoor relative humidity. Using fans has the potential to enhance the air quality by reducing pollution in the occupied zone, and to improve the overall thermal sensation. The drawback of using fans was the risk of discomfort due to the peaks in air speed caused by rotation of the fans, which must be prevented to attain comfortable conditions. Turning the air conditioning on during prayers was not an efficient strategy to improve thermal comfort. It is recommended to consider pre-cooling of the mosque and keep air conditioners off during prayers.