PMV Values Research Articles

Study on Human Thermal Comfort in Asymmetric Radiant Heat Environment in Large Space

In order to study indoor temperature distribution in a large space and thermal comfort of human, an environmental test and questionnaires were carried out at an airport in Xi’an in summer. The results show that the temperature distribution in the space is asymmetric. The room temperature increases from cooling floor to 0.1m high, but then it has little change within 1.5m high. However, the temperature fluctuation in horizontal is significantly influenced by internal equipment, lighting, elevator and etc. According to the environmental parameters and subjective voting, 55% of the PMV values are greater than 0.5, and more than half of the thermal feelings near the heat source and glazing curtain wall are “warmer”. Properly increasing the wind speed of air vent could effectively improve the environmental comfort.

Thermal Comfort Performances of Temporary Shelters Using Experimental and Computational Assessments

This paper examines the thermal comfort of temporary shelters under Taiwan’s subtropical summer conditions. The temperature within the tent was higher compared to the standard configuration of the temporary shelter, but its relative humidity was lower. During the time period 09:30 to 14:30, temperatures at the center of the tent at positions 0.10 m, 1.10 m and 1.70 m above ground were 3.1 °C, 5.5 °C and 6.0 °C higher, respectively, than the average ambient temperature of 36.3 °C. However, temperatures for the standard configuration at similar central positions of 0.10 m, 1.10 m and 1.70 m above ground were 1.2 °C, 0.5 °C and 0.7 °C lower, respectively, than the same average ambient. In the afternoon, the standard configuration (PMV of 3.14 and PPD of 100) performed better than the tent (PMV of 5.03 and PPD of 100), although neither achieved thermal comfort. Various experimental configurations showed that double layers of roof lowered temperatures, but the thermal comfort (PMV of 3.32 and PPD of 100) remained unchanged. Various computational configurations showed that closing the door and one window and installing a mechanical fan of average speed 2.75 m/s lowered the temperature and increased the air speed to achieve thermal comfort with PMV and PPD values of 1.49 and 50, respectively.

Thermal Comfort Study Based on PMV-PPD in the Building of a Screening Center for COVID-19

Background: One way to achieve a standard heating, ventilating, and air conditioning system with maximum satisfaction is to use a thermal index to identify and determine the thermal comfort of people. In this study we intend to evaluate thermal comfort based on PMV-PPD (Predicted Mean Vote/Predicted Percentage Dissatisfied) model in workers of screening center for COVID-19. Methods: The study period was from March 1 to October 31, 2020. In this study, we used the ISO 7730 model to determinate PMV-PPD index. PMV index was used to determine thermal comfort at different scales in Birjand city with arid and hot climate. All data were analyzed using R software (version 3.3.0) and IBM SPSS statistics softwares. Results: The maximum and minimum recorded physical PMV values in the study period were observed in June as (2.09 ± 0.03) and March as (-1.27 ± 0.14), respectively. The amplitude of the thermal sense in the study period was varied between slightly cool (-1.5) and warm (+2.5). The PPD in spring was 40% which indicated slightly warm to hot condition. Conclusions: The October was the only month during the study in which thermal stress was in comfort or neutral thermal condition. Our results suggest that thermal comfort has dimensions and indices which are helpful in managing energy consumption.

Effect of Exposure Time on Thermal Behaviour: A Psychophysiological Approach

This paper presents the findings of a 6-week long, five-participant experiment in a controlled climate chamber. The experiment was designed to understand the effect of time on thermal behaviour, electrodermal activity (EDA) and the adaptive behavior of occupants in response to a thermal non-uniform indoor environment were continuously logged. The results of the 150 h-long longitudinal study suggested a significant difference in tonic EDA levels between “morning” and “afternoon” clusters although the environmental parameters were the same, suggesting a change in the human body’s thermal reception over time. The correlation of the EDA and temperature was greater for the afternoon cluster (r = 0.449, p < 0.001) in relation to the morning cluster (r = 0.332, p < 0.001). These findings showed a strong temporal dependency of the skin conductance level of the EDA to the operative temperature, following the person’s circadian rhythm. Even further, based on the person’s chronotype, the beginning of the “afternoon” cluster was observed to have shifted according to the person’s circadian rhythm. Furthermore, the study is able to show how the body reacts differently under the same PMV values, both within and between subjects; pointing to the lack of temporal parameter in the PMV model.

Case Study of Thermal Comfort in a Temporary Shelter

In Latvia to perform COVID-19 tests as well as for temporary shelters in case of a local disease outbreak the persons were located in special tents. Such practice was not only performed locally but also in other countries like the USA, UK, Russia, etc. The wide usage of tents was possible as the outbreak happened during the warm period of the year. At the same time, the indoor climate of tents can be quite unbearable during the warm summer days. Also, the situation was not getting better as fast as the prognosis, and the crisis was still ongoing during the winter period. Therefore, to test the thermal comfort of such temporary shelter’s measurements were performed. The thermal comfort was measured in a tent from 27th May to 28th September 2020. The data was logged with three different measuring devices inside of the shelter as well as outside air parameters like temperature and solar radiation was logged. The results show the rapidly changing indoor temperature which reaches 40°C during the daytime and falls to 10°C at night. The data of the globe thermometer to analyze the influence of radiation from tent canvas was also studied and showed that there is no noticeable heat radiation from external walls. The PMV measurements showed that the thermal comfort is very low as the PMV values were outside the range of -1 to 1 for 57% of the time. The influence of the precipitation was also noted, and the results showed that the adiabatic cooling effect is very variable but in general does not noticeably change the indoor temperature, the average temperature decrease was only 1 °C, but for a specific case it reached 10°C.

Design and control of radiant ceiling panels incorporating phase change materials for cooling applications

Experimental and numerical studies have demonstrated that thermally activated building systems (TABS) may lead to significant energy savings. However, TABS are generally incorporated into the building during the construction phase, limiting their adoption to new buildings. To encourage the application of TABS during building refurbishments, the authors have developed a radiant ceiling panel (RCP) with macroencapsulated phase change materials (PCM). This study aims to provide the criteria to design, size, and control the newly proposed RCP-PCM system. A simplified method to size and design the RCP-PCM system for cooling applications is developed from a set of parametric dynamic simulations. At first, the thermal storage properties of the macro-encapsulated PCM were determined using the standard ASTM C1784-20. The obtained properties were then used in a whole-building simulation model validated using measurements in a small test chamber that replicates the conditions of an actual test room. The PCM panel thickness of 0.015 m and a supply water temperature of 15 ℃ showed the best results in terms of thermal comfort and effective thermal energy storage capacity. The implementation of the simplified method in a case study showed that the RCP-PCM system maintained room conditions within the specified thermal comfort range (−0.5 < PMV < 0.5) for more than 90% of the occupied periods in all of the evaluated cooling-dominated climates. Moreover, yearly-round, the PMV values never reached values higher than 0.8 or lower than −0.6, confirming the effectiveness of the proposed method for designing a RCP-PCM system. The results show that energy savings of 22% could be obtained in a very hot and humid climate using an RCP-PCM system instead of a conventional all-air system. In conclusions, this paper offers a new system to promote energy flexibility and Demand-Side Management (DSM) strategies to modulate the energy demands in retrofitted buildings.

The Use of Green Design Strategies for Achieving Thermal Comfort (Applying PMV as a Measurement Tool)

Improving outdoor thermal comfort is a key parameter in achieving the vitality and functionality of urban spaces. In order to build a thermally comfortable outdoor space, designers must consider suistainable urban, architectural, and landscape design solutions. The main problem is that most of recent developments in Egypt didn’t consider the use of green design strategies which resulted in human outdoor thermal discomfort. In this research, a case study in Egypt, characterised by hot arid climate is used to discuss and quantify the impact of green design strategies on urban microclimate and human sense of thermal comfort. The methodology used is based on Envi-met simulation to measure the four climatic parameters and PMV index. The outcomes indicated that significant enhancement in thermal comfort was achieved with the trees coverage, Where Using the maximum tree coverage showed the best improvement in PMV values with a drop of 2.48 at peak hours when compared to the base case. The results showed that the use of trees is an important strategy to improve the micro-climatic conditions and human thermal comfort in open spaces due to the shading effect as they block out excessive solar radiation.

Performance of the wall implanted with heat pipes on indoor thermal environment

In order to improve the utilization of solar energy absorbed by the building wall, a passive building technology, that is the wall implanted with heat pipes, had been proposed. In the present study, two rooms with the same environmental conditions were built, and the one with a wall implanted with heat pipes installed was taken as a test room and the other as a control. The dynamic heat transfer characteristics of a wall implanted with heat pipes in transition season and its impact on indoor thermal environment were studied experimentally. The results showed that the application of a wall implanted with heat pipes could increase the indoor temperature by about 0.5 °C and would assert a positive influence on the vertical distribution of temperature. The PMV-PPD values of two rooms were calculated to compare and evaluate the improvement in thermal comfort, and the results indicated that the wall implanted with heat pipes reduced the dissatisfaction rate by more than one seventh in comparison to the indoor thermal environment. Also, it enhanced the PMV value. Therefore, wall implanted with heat pipes as an auxiliary heat source has a good effect on the indoor thermal environment during the transition season.

CFD Study on Thermal Implication towards Human Body in Office Environment

Temperatures are rising gradually around the world due to the issue of global warming. This condition also affects those who have to work for long hours. A comfortable work environment helps employees to increase work productivity. Thermal comfort is the occupant’s satisfaction with the surrounding thermal conditions. Therefore, the objective of this study is to evaluate the thermal environmental conditions of air conditioning through Computational Fluid Dynamics simulations. The distributions of environmental parameters such as air velocity, air temperature, radiant temperature, inside an o?ce room with air-conditioning are presented. Based on these distributions, spatial pro?les of Predicted Mean Vote Index (PMV) are obtained to illustrate thermal conditions intuitively. This study was conducted under controlled environment inside special laboratory. To achieve this model office environment has been built in an environmental chamber. The distribution of PMV indicates that operative temperature at the 23 oC shows that the PMV is comfortable. The value of PMV in operative temperature at 23 oC is 0.79 near the skin of an occupant. The research outputs provide useful information for designers of the air-conditioning system to build a comfortable indoor environment in the office environment.

Compliance with limits of acceptability for thermal comfort, and implications for long-term comfort

This paper illustrates the derivation of a method to check whether conditions in a given indoor work environment comply or do not comply with the relevant limit of acceptability for thermal comfort. The proposed method advocates that measurement uncertainties should be ignored, as they are way too large for consistency with the existing scheme of closely-spaced thermal categories outlined in international standards. It focuses instead on the identification of a representative value of the synthetic thermal comfort index PMV to be compared with the limit of acceptability. Because indoor thermal environments, even when air-conditioned, exhibit non negligible daily and seasonal fluctuations, care must be taken to ensure that this representative value of PMV reflects thermal conditions approaching the worst case. Because the actual distribution of PMV in a given environment is unknown, the distribution of the outdoor temperature Tout is used as a proxy, and a representative value of Tout is identified in terms of a specific quantile of the summer/winter distributions. This implies that PMV can be considered adequate for comparison with limits if based on measurements carried out when the outdoor temperature is near a specified quantile of the summer/winter distributions.As a byproduct, results have been used for improving the existing methods for evaluation and assessment of long term comfort. To this aim, a more appropriate expression for weighting different exposures has been derived, and a limit of acceptability has been identified.

Efficiency of Solar Shading Devices to Improve Thermal Comfort in a Sports Hall

Thermal environment in sports facilities is probably one of the most important parameters, determining the safety and performance of athletes. Such facilities, due to the required operating temperature and physical activity of users, are a serious challenge for both investors and administrators, especially in summer. The additional criterion of low energy consumption in extremely airtight and well-insulated passive buildings often results in overheating of the interior, creating considerable economic and operational problems. The significant need to reduce solar gain during periods of high outdoor temperatures for low-energy buildings prompts a variety of design solutions. Sun shading systems, as an indispensable element of glazed surfaces, are designed to control the amount of solar radiation reaching the building interior, at the same time creating a favorable microclimate inside. This article analyzes the effects of sun shading, which have actually been applied and modified on the southern façade of a passive sports hall in Słomniki. Measurements of the thermal conditions in the hall were the starting point, on the basis of which a model of the object was created in the DesignBuilder program. Using simulation analyses, thermal conditions arising with the use of different variants of internal and external shading devices were studied in the program. The results presented in the article show that in a well-insulated hall of large volume, appropriately selected external shading devices are only able to reduce the access of sunlight to the rooms. External brise-soleils are able to limit the access of solar radiation to the rooms by up to 30%, but this is not enough to guarantee internal thermal comfort. Internal blinds do not affect the interior microclimate significantly and do not protect protection from overheating. Momentary differences in PMV values for different patterns of closing the blinds do not exceed 0.2.

MODERN METHODS OF THERMAL COMFORT MEASUREMENTS

The issue of thermal comfort and its subjective feelings inside a building is becoming more and more important in the modern world. It is caused by the desire to create optimal conditions in places where people stay. The article presents two methods, indirect and direct, which are typically used in the research projects. These methods enable to assess the thermal sensations of people and compare the feelings of the respondents with the value of PMV (the value of human thermal sensations) calculated using the formula from the ISO 7730 standard and the questionnaire surveys.

Tailored WBGT as a heat stress index to assess the direct solar radiation effect on indoor thermal comfort

Uncontrolled solar radiation and the related effects on occupant productivity can lead to considerable indoor thermal discomfort in office environments. In this paper, the Radiance Daylight Coefficient (DC) method is used to assess incoming solar radiation and consequent indoor thermal discomfort through delta mean radiant temperature (ΔMRT). The ΔMRT allows expressing an adjusted predicted mean vote (Adjusted PMV). Under the conditions of direct solar radiation, the Adjusted PMV value surpasses the applicability range of the standard PMV in terms of MRT value. To overcome this limitation, the assessment of the effect of incoming shortwave solar radiation is expressed in the heat stress index of wet bulb globe temperature (WBGT). This procedure was tested under a variety of climatic conditions (e.g., Sol-air temperature) to estimate dissatisfaction in indoor office environments located in Milan (Italy) for an occupant positioned at different distances from the fenestration (0.75 m, 1.25 m, and 1.75 m) and exposed to direct solar radiation (e.g., without shading devices). The condition with no shading device was then compared with the condition with shaded glazing to test the impact of the solar radiation on the indoor thermal stress conditions. The results reported through ΔWBGT allow the estimation of the heat stress conditions on an annual basis when ΔWBGT > 0. Finally, it is proposed that the metric of Annual Radiation Heat Stress (ARHS) should include ΔWBGT and assess the heat stress spatially due to the incoming direct solar radiation.

Sustainable Urban Greening and Cooling Strategies for Thermal Comfort at Pedestrian Level

The increase of the urban warming phenomenon all over the world is gaining increasing attention from scientists as well as planners and policymakers due to its adverse effects on energy consumption, health, wellbeing, and air pollution. The protection of urban areas from the outdoor warming phenomenon is one of the challenges that policy and governments have to tackle as soon as possible and in the best possible way. Among the urban heat island mitigation techniques, cool materials and urban greening are identified as the most effective solutions in reducing the urban warming phenomenon. The effects produced by the adoption of cool materials and urban forestation on the urban microclimate were investigated through a computational fluid-dynamic (CFD) model. The CFD model was calibrated and validated thanks to experimental surveys within the Catania University campus area. The urban microclimate thermal comfort analysis and assessment were carried out with the Klima–Michel Model (KMM) and Munich Energy Balance Model for Individuals (MEMI). In particular, three scenarios were performed: cool, low, and high levels of urban greening. The cool scenario, although it produces air temperature at around 1.00 °C, determines the worst condition of outdoor thermal comfort, especially at the pedestrian level. On the contrary, a high level of urban greening, obtained by the extensive green roofs together with an urban forestation, guarantees the wellbeing of pedestrians, showing more convenient values of PMV and PET.

Investigation on Numerical Simulation of Radiation Heating Thermal Environment in Car Cabin

Based on the automobile energy saving and requirements for thermal comfort of heating environment in a car, a capillary radiation heating system for automobile is presented, and the 3D flow field and temperature field of air in the passenger compartment are simulated by using SC/Tetra software. To consider the effect of human thermoregulation, human thermal regulatory model is incorporated with numerical simulation. The thermal comfort of passenger compartment is evaluated by PMV-PPD comfort index basing on the simulation results. It concludes that the distributions of flow field and temperature field of radiation heating environment are relatively homogeneous. Human thermoregulation has a big influence on the temperature distribution in the near region around the human body. Analyzing the PMV values of body surfaces, it concludes that the radiation penal surface temperature should be set to 30°C under the most comfortable environment for human. The research results provide basis for the using of radiation heating technology in a car.

Experimental investigations and computational thermal simulation on human thermal comfort during performing office tasks

Thermal have significantly impact the productivity of work as well as the occupants’ satisfaction to their surroundings. The objective of this study is to evaluate the implication of thermal environmental conditions to human/manikin in a ventilated air conditioning space using CFD simulations. The thermal distributions of environmental parameters, which were air velocity, air temperature, radiant temperature, inside an office room with air-conditioning system were simulated. The design of experimental study was utilised through the controlled conditions based on the real laboratory studies and real case studies which were later on utilised as the external validity of the field studies. The model of the office environment has been built in the ANSYS Engineering simulation software. The thermal distributions, spatial profiles of PMV are obtained to illustrate thermal conditions intuitively. The distribution of PMV indicated that operative temperature at the 23 °C shows that the PMV is at the level of comfort. Meanwhile the value of PMV for the operative temperature at 23 °C is at 0.79 near the skin of manikin. The research outputs provide useful information for engineers especially in designing air-conditioning system in order to design and build a comfortable indoor environment climate especially in the office environment.

Study on Indoor Thermal Environment of Traditional Dwellings in the Watery Town in Suzhou in Winter

Traditional dwellings have their own characteristics and values in the construction of indoor thermal environment. In order to analyze the current situation of thermal environment of dwellings in Southern Region of the Yangze River. This paper takes traditional dwellings in the watery town in Suzhou as the research object, and studies the indoor thermal environment in winter through field measurement of indoor and outdoor temperature and relative humidity of dwellings in winter, questionnaire survey and PMV-PPD thermal evaluation system. The results show that the average indoor temperature is 7.5°C, humidity of residential is 72%, the average predicted thermal sensation vote is -2.79, the predicted dissatisfaction is over 90%, and the indoor thermal environment dissatisfaction in public questionnaire survey is 20.83%, which is far from the predicted dissatisfaction PPD. It shows that the vote of hot feeling underestimates the residents' tolerance for the environment, and corrects the deviation of PMV value through adaptive coefficient. The revised aPMV value is greater than PMV value, but the thermal and humidity environment level is still Class III, which does not meet the living conditions. Water source heat pump can be used as a heating method in winter to improve the thermal environment, which can provide reference for improving indoor thermal environment of residential buildings in water towns.

Thermal comfort analysis in the sustainable educational building

In the modern world, a person spends most of his life indoors. That is why it is so important to create optimal conditions for the internal environment. Research on thermal comfort and subjective feeling of people inside the building can help in this. The article discusses two methods that are used in research on thermal sensations. This makes it possible to know the thermal assessment of people and then compare this result with the calculated PMV value, which is calculated using the formula from ISO 7730 standard.

Retrofit planning and execution of a mediterranean villa using on-site measurements and simulations

In this research, a full rehabilitation study (retrofit) of an isolated villa in a Mediterranean climate was carried out in order to show how a retrofit of a building with a combination of simple passive and active strategies can improve the sustainability, energy efficiency and the thermal comfort. This is performed thanks to the design of a methodology of using a thermal simulation tool with experimental measurements based on a low-cost open source hardware platform in order to evaluate the energy saving measures and analyse the thermal comfort and energy savings. To accomplish this, a study of the housing needs is performed a priori to later design the different actions in the rehabilitation, using if possible, ecological materials in its development. Basically, walls and ceilings are insulated, three solar air collectors are included to heat the air ventilation and decrease the heating demand, and two pellet stoves are installed. Finally, the refurbished house is modeled and simulated in EnergyPlus and compared with the indoor air temperature and relative humidity measurements, made using an Open-Source Monitoring System (OSMS) developed for this research in Arduino, obtaining results with no significant differences without the need to calibrate the system. The results of thermal comfort, heating and cooling demand and heating energy consumption of the house before and after the renovation are compared providing a decrease in thermal demand of 66% and a decrease in heating energy consumption of 50% in the winter season, where 60% of the energy consumed is contributed from renewable sources. In terms of thermal comfort, the comparison of the PPD and PMV values shows an improvement in the house in heating and cooling season.

Research on Temperature Control of Hospital Operating Room under Near Comfortable Conditions

Air temperature has a significant impact on human thermal sensation. It directly affects the heat exchange between the human body and the environment. It is the most important factor in the PMV index that affects human thermal sensation. Clothing thermal resistance is also one of the factors that affect human thermal sensation PMV. In the operating room of a hospital building, because the clothing of the operating staff is different from that of the ordinary office environment staff, the corresponding clothing has different thermal resistance values, which will directly affect the design temperature setting of the operating room. Close to the comfort zone, when wearing surgical gowns, through Matlab programming, the relationship between the PMV value in the operating room and the indoor set temperature and air flow rate is explored in detail, in order to improve the working environment of the operating room personnel and the energy saving of the operating room air conditioning system Provide a reasonable basis.