Comfortable Thermal Environment Research Articles

Study of indoor local thermal comfort for impinging jet ventilation combined with ductless personalized ventilation under different cooling loads

Excessive temperature stratification and draught are two prominent drawbacks for impinging jet ventilation (IJV). Using IJV together with ductless personalized ventilation (DPV) (i.e., IJV + DPV) has been proved to be an effective way to reduce temperature stratification, but the draught rate around occupant would be increased. In the current work, an in-depth study on the characteristics of indoor local thermal comfort for IJV + DPV operating with different scenarios is done. Predictive models for the local thermal comfort indicators are developed to optimize the operating parameters (including supply velocity of IJV (Vs) and intake airflow rate of DPV (Df)) with different room cooling loads (Q). The results show that the application of IJV can be extended to spaces with high cooling loads (e.g., larger than 60 W/m2) by using together with DPV, but the risk of thermal discomfort increases. To avoid local thermal discomfort, the combination relationship between Vs and Df should be properly matched and this relation becomes more stricter with the increase of Q. It also obtains that the maximum cooling load that IJV + DPV can eliminate is less than 170 W/m2. At last, to ensure the IJV + DPV create a good local thermal comfort environment, design chart about the feasible ranges of Vs and Df are established for different values of Q. On the whole, the current study not only can provide a basis for the application of IJV + DPV in spaces with high cooling load, but also can provide theoretical guidance for the operation control and optimization design of the IJV + DPV.

Sustainable Thermal Comfort by Age Group in Shopping Malls: Multi-Year Winter Surveys in a Severely Cold Region

The current Chinese standard utilizes a single thermal comfort index guide to regulate indoor parameters for public buildings. However, heating, ventilation, and air conditioning (HVAC) settings often do not align with the occupant’s needs. To address this, a 2-year winter field survey was conducted in four large-scale shopping malls across severely cold regions of China, considering the complex age structure of mall visitors. Physical environmental parameters were measured, and a subjective questionnaire yielded 1464 valid responses. Neutral temperatures for different age groups were 17.4 °C for children (0–12 years of age), 19.3 °C for early youth (13–24), 20.0 °C for mature youth (25–44), and 23.3 °C for middle-aged adults (45–59). The limit of the 80% acceptable temperature range for the children and early youth was lower than the current Chinese GB 50736 standard, suggesting that HVAC temperatures for the corresponding shopping malls can be appropriately reduced for the target consumer groups. Significant differences occurred between customers’ demand for thermal environments in shopping malls and various standards. These findings provide valuable insights into energy-efficient architectural design and operational management of shopping malls in the Shenyang area, promoting the sustainable development of human thermal comfort environments.

Energy- efficient cementitious mortar containing clay based shape-stable phase change material: Development, characterization and temperature controlling performance

The need for buildings to ensure a comfortable thermal environment is increasing, leading to a surge in energy consumption. This study proposes an innovative approach to tackle thermal energy storage challenges in buildings by formulating a unique cementitious mortar containing a shape-stable composite of Saudi Arabian natural clay and methyl stearate phase change material (PCM). The inclusion of natural clay, chosen for its cost-effectiveness and eco-friendliness, addresses the issue of methyl stearate leakage—a common concern with PCM usage. Despite PCM incorporation, the mixture maintains desirable fluidity and consistency, albeit with a slightly reduced dry unit weight and compressive strength. Differential scanning calorimetry analysis defines key characteristics of the resulting shape-stable NC/MS composite PCM, including a melting point of 33.81°C and a latent heat storage capacity of 56.15 J/g. Empirical testing demonstrates the efficacy of the natural clay/PCM composite in temperature moderation. During periods of elevated external temperatures, the NC/PCM specimen effectively lowers room-center temperatures by up to 4°C and sustains a cooler environment compared to the control room for almost 8 hours. Additionally, the composite PCM limits the maximum increase in room center temperature post-sunset to only 2.49°C, showcasing its capability in stabilizing indoor temperatures. This innovative PCM composite responds dynamically to ambient temperature variations, transitioning between solid and liquid states to release stored latent heat, consequently reducing building heating and cooling loads, enhancing energy efficiency. The natural clay/PCM composite presents a promising solution for advancing building thermal energy storage systems, aligning with energy efficiency and sustainable design objectives.

A Review of In-Flight Thermal Comfort and Air Quality Status in Civil Aircraft Cabin Environments

The civil aircraft cabin is enclosed and highly occupied, making it susceptible to a decline in indoor environmental quality. The environmental quality of civil aircraft cabins not only depends on objective factors such as temperature, relative humidity, and the presence of air pollutants such as carbon dioxide (CO2), carbon monoxide (CO), ozone (O3), particle matter (PM), and volatile organic compounds (VOCs) but also the subjective factors pertaining to the perceptions and health symptoms of passengers and crew. However, few studies have thoroughly examined the air quality and thermal comfort parameters that are measured during in-flight testing in airplane cabins, as well as the passengers’ subjective perceptions. In order to evaluate the in-flight thermal comfort and air quality status, this study conducted a review of the recent literature to compile data on primary categories, standard limits, and distribution ranges of in-flight environmental factors within civil aircraft cabins. Following a search procedure outlined in this paper, 54 papers were selected for inclusion. Utilizing the Monte Carlo method, the Predicted Mean Vote (PMV) distributions under different exercise intensities and clothing thermal resistance were measured with the in-cabin temperature and humidity from in-flight tests. Recommendations based on first-hand data were made to maintain the relative humidity in the cabin below 40%, ensure wind speed remains within the range of 0–1 m/s, and regulate the temperature between 25–27 °C (for summer) and 22–27 °C (for winter). The current estimated cabin air supply rate generally complies with the requirements of international standards. Additionally, potential carcinogenic and non-carcinogenic risks associated with formaldehyde, benzene, tetrachloroethylene, and naphthalene were calculated. The sorted data of in-flight tests and the evaluation of the subjective perception of the occupants provide an evaluation of current cabin thermal comfort and air quality status, which can serve as a reference for optimizing indoor environmental quality in future generations of civil aircraft cabins.

Multi-Objective Optimization of Morphology in High-Rise Residential Areas for Outdoor Thermal Comfort in Yulin City, Northwest China

Urban residential areas significantly influence outdoor thermal comfort through architectural morphology. This study concentrates on the multi-objective optimization of the thermal comfort environment in residential areas, with a focus on Yulin—a city in the cold, inland region of Northwestern China. Yulin is characterized by its distinctly defined seasons, particularly harsh and windy conditions in the spring, which significantly impact thermal comfort. Utilizing field surveys, characteristics of scale and layout from high-rise residential areas in Yulin were extracted to formulate design strategies adapted to local climates. The Universal Thermal Climate Index (UTCI) served as the optimization criterion, and genetic algorithms, integrated with parametric modeling software, generated multiple layout schemes. These were refined through the Pareto evolutionary algorithm II to optimize thermal comfort across seasons. Furthermore, the Sobol’ sensitivity analysis method was employed to assess the impact of key parameters on outdoor thermal comfort, identifying crucial layout design elements. The optimization improved UTCI values for different seasons, ensuring year-round comfort. Specifically, summer UTCI improved to 25.51, while winter and spring values reached optimal values of −14.02 and −6.41, demonstrating enhanced thermal retention and reduced wind exposure. Sobol’ sensitivity analysis identified building length, orientation, and density as key parameters, highlighting their critical impact on thermal comfort. This study offers practical guidelines for urban residential area design in similar climatic zones, aligning architectural planning with environmental sustainability and enhancing thermal comfort effectively. This study provides practical guidelines for the design of residential areas in cold inland—seasonal windy—regions and other similar climatic zones, aligning building morphology design with environmental sustainability and enhancing thermal comfort effectively.

Quantifying surface urban heat island variations and patterns: Comparison of two cities in three-stage dynamic rural–urban transition

Urban heat island (UHI) not only reflects the environmental thermal comfort and energy consumption, but also affects the urban meso‑scale climate. There are many researches related with UHI mainly focusing on urban and rural area, while neglecting dynamic rural–urban transition especially in a rapid urbanization in China. Beijing and Zhengzhou are studied by using city clustering algorithm (CCA) and boundary generation algorithm (BGA) to delineate the urban, peri‑urban and rural boundaries from 2000 to 2023 within three stages. Fourier transform model was used to identify the UHI patterns. Results show: 1) Two cities have undergone obvious expansions in 20 years, with a consistent mean LST decrease from urban to peri‑urban and rural areas in three stages. 2) The distribution of UHII was more consistent in Beijing, while it varied more in Zhengzhou across seasons. 3) The UHI patterns notably differ, with Zhengzhou experiencing variable patterns and Beijing consistently showing oblate patterns. 4) The profiles of UHII and NDVI in two cities varied seasonally and reflected urban expansions in terms of longitude and latitude. Understanding the long-term changes and patterns of urban heat islands in different cities will provide information for formulating adaptive policies for urban sustainability.

Investigating the New Product CCF-DGU without Coatings for Thermal Comfort in a Tropical Indoor Environment

Investigating the New Product CCF-DGU without Coatings for Thermal Comfort in a Tropical Indoor Environment

Research on Energy-saving Design for University Library Spaces in Cold Regions

With the popularization of open-shelf reading in university library, the change of use mode leads to the change of space mode, and gradually develops from corridor mode to large-scale and deep composite centralized space organization mode. However, the large and deep open reading space and atrium space in university libraries increasingly rely on artificial lighting, mechanical ventilation and mechanical temperature regulation to meet the comfort needs of space thermal environment. Moreover, the improper control of passive design strategy in the early stage further leads to the reduction of indoor thermal environment comfort and the increase of building energy consumption. In the early stage of architectural design, through reasonable passive space layout design, the use of air conditioning equipment can be greatly reduced, energy consumption can be reduced, and the goal of green development can be achieved. Through extensive collection and analysis of 23 university libraries built in cold climate region, by making a statistical study on the building type, building area, number of floors, building scale and building plane aspect ratio, summarizing and extracts the prototype. Referring to the typical cases in cold climate area, two core groups that reading spatial variable group and atrium spatial variable group are proposed by controlling a single variable, in which each group has four plane layout modes. The dynamic energy consumption simulation software DesignBuilder is used to simulate the annual cooling, heating and lighting load of each group in cold climate region, and the results are converted into energy consumption values for analysis. The final results show that among the four combination modes of reading spatial variable group, the overall energy consumption of compound type is the smallest, and the energy-saving rate is the highest, up to 3.71%. The overall energy consumption of parallel type and surround type is little difference, and the overall energy consumption of surround type is the highest. The energy-saving rate of the four groups of reading modes is as follows: compound type > decentralized type > parallel type > surround type. The total energy consumption of the atrium partial staggered floor group is lower than that of the non staggered floor group. Among the four combination modes of the atrium spatial variable group, the overall energy consumption of the organization form of the atrium partial staggered floor to the south is the smallest, the energy-saving rate is the highest, reaching 5.84%, and the energy-saving rate of the atrium partial staggered floor to the north is the lowest. Therefore, in the preliminary scheme design stage, low-performance spaces such as traffic auxiliary space can be placed at the building boundary to form a buffer zone similar to the transition space, so as to alleviate the negative impact of the external adverse climate environment on the internal space. At the same time, it can be considered to carry out partial staggered floor design of the atrium, and give priority to arranging the atrium on the south side, which is not only conducive to reducing the overall energy consumption of the building and achieving the energy-saving goal, but also enhance the diversification of vertical sections and promote the interest of the internal space of modern university libraries.

Impact of Urban Forest and Park on Air Quality and the Microclimate in Jinan, Northern China

Though the impact of urban vegetation on air quality and the microclimate has attracted increasing attention, there have been few studies quantitatively assessing this impact in North China, where air pollution is severe. In this study, we investigated the impact of urban forests and urban parks on air quality and the microclimate in Jinan, northern China. Six sites were chosen to represent urban forest, urban park, and downtown areas, respectively. The results indicate that urban forest can effectively reduce PM2.5 and ozone (O3) concentrations in the warm season, when temperatures are higher and plants are lush. The PM2.5 and O3 concentrations in the urban forest areas were 6.3–6.5 μg m−3 and 21–23 μg m−3 lower than those in downtown areas during the period of 10:00–15:00. In contrast, urban park areas can reduce PM2.5 concentrations but have little impact on gaseous pollutants such as nitrogen dioxide and O3. Furthermore, both urban forest and urban park areas reduced temperatures, by approximately 4.1–6.8 °C and 1.36 °C, respectively, and increased relative humidity, by about 13.4–12.9% and 0.9%, promoting a more comfortable thermal environment for residents. Therefore, this study highlights the crucial role of urban vegetation in improving air quality and creating a comfortable environment for residents.

Preparing gypsum-based self-levelling energy storage mortar via fly ash cenospheres/paraffin used for floor radiant heating

In the underlayment of a floor radiant heating system (FRHS), using gypsum-based self-levelling mortar (GSM) with high fluidity and early strength properties could save labor force and material costs. Combining phase change materials (PCMs) with FRHS is a promising way to improve energy efficiency and provide a comfortable thermal environment. This paper investigates the feasibility of preparing gypsum-based self-levelling energy storage mortar (GSEM) by incorporating fly ash cenospheres/paraffin (FACP) into GSM. The selection of fly ash cenospheres (FAC) particle size, the pre-treatment of FACP, the additional amount of FACP, and the thermal performance of FRHS containing GSEM are investigated. Results show that the selection of FAC should consider the influence of strength, fluidity, thermal property, and possible economic and environmental impacts. FAC 2 with a particle size (D50) of 110.5 µm is considered to be a suitable choice. FACP pre-treated with 52.5 cement could decrease paraffin leakage and increase the mechanical strength and fluidity of GSEM. With the sand replacement ratio (Vf) increase, the mechanical strength of GSEM first increases and then decreases. When the Vf is 100%, the compressive strength and flexural strength of GSEM are 18.8 MPa and 4.3Mpa; the thermal conductivity decreases by about 15.8% and the specific heat capacity increases by about 53.5%. For FRHS, the matching between the supply water temperature and the plate thickness should be considered in the design. Compared with the GSM plate, the GSEM plate could reduce about 2.4℃ temperature fluctuation, and the time at a comfortable temperature is extended by 60.8%. This finding indicates that the prepared GSEM could be applied to FRHS and has good potential to provide a comfortable thermal environment for buildings.

Relative thermal pleasure model: A unified framework for understanding and predicting thermal comfort in dynamic environments

Thermal comfort within dynamic environments is shaped by a combination of factors including thermal adaptation levels, short-term thermal histories, thermal expectations, and non-thermal stimuli. However, existing thermal comfort models have fallen short in providing a unified theoretical framework capable of elucidating the combined impact of these factors on thermal comfort. Here, we introduce the Relative Thermal Pleasure (RTP) model, which offers a unified theoretical framework for both elucidating and predicting thermal pleasure. The RTP model posits that the contrast between the target thermal stimulus and its reference points, in conjunction with the distribution of attention weights among these elements, together determine the emergence and intensity of thermal pleasure. To validate the model's predictions and determine model coefficients, nineteen participants were recruited to access their thermal pleasure between two warm environments with different temperatures ranged from 32 to 45 °C. The RTP model clarifies the psychological mechanisms underlying the generation of thermal pleasure and elucidates how external environmental factors and internal psychological and physiological factors influence thermal pleasure. Through theoretical and experimental analysis, we found that improving a poor thermal environment may or may not trigger thermal pleasure, depending on the improvement percentage in the thermal environment. The critical improvement percentage to induce thermal pleasure is 48.7%. The findings of this study have the potential to advance our understanding of thermal comfort and guide us in creating more comfortable thermal environments.

Summer Thermal Challenges in Emergency Tents: Insights into Thermal Characteristics of Tents with Air Conditioning

Emergency tents face challenges in harsh weather conditions and sometimes require the use of air conditioning for indoor thermal environment control. However, their lightweight structure makes their control methods different from conventional buildings. This study focuses on the indoor thermal environment and thermal comfort of air-conditioned tents during summer. Through experimental measurements, this study captures the distribution of air temperatures and inner surface temperatures within a tent, thus providing an understanding of the characteristics of indoor thermal environment in air-conditioned settings. Additionally, the numerical simulations conducted using the ANSYS FLUENT 2021 R1 calculate the Predicted Mean Vote (PMV) and Predicted Percentage Dissatisfied (PPD), thus contributing to a detailed analysis of the indoor thermal comfort states. The experiment revealed that the mean radiative temperature (MRT) inside the tent can exceed the air temperature by more than 10 °C. Even when the air temperature is around 26 °C, the excessively high MRT can cause occupants to feel uncomfortable, with the PMV exceeding 1.4 and the PPD surpassing 50%. Furthermore, the high MRT results in an increased demand for cooling airflow, with the cooling loss through gaps becoming a significant part in the cooling load. To ensure a comfortable thermal environment, the air-conditioning set temperature needs to be adjusted according to the weather conditions. For instance, even at the same air temperature of 35 °C, when solar radiation increases from 400 W/m2 to 1000 W/m2, the set temperature needs to be reduced from 24.7 °C to 20.7 °C. The findings of this study provide an important reference for establishing summer air-conditioning strategies for emergency tents.

Unraveling the link between draught and upper respiratory mucosal immunity: Assessing lysozyme and S-lgA concentrations in nasal lavage fluid

The purpose of this study is to investigate the effect of draught on upper respiratory tract mucosal immunity, by assessing concentrations of lysozyme and secretory immunoglobulin A (S-IgA) in nasal lavage fluid. A total of 26 subjects were recruited and experienced 4 experiment conditions combined with two ambient temperatures (24 °C and 28 °C) and two air velocities towards the nape (0 m/s and 1 m/s). Physiological parameters, and subjective questionnaires (i.e., thermal sensation vote (TSV), thermal comfort vote (TCV), and air movement vote (AMV)) were also collected. Our findings revealed that physiological parameters fluctuated significantly under 24 °C, 1 m/s (p < 0.05). Significant decreases in lysozyme concentration occurred under both 24 °C, 1 m/s (p = 0.003) and 24 °C, 0 m/s (p = 0.017). S-IgA concentrations significantly decreased after one-day lag (p = 0.028) under 24 °C, 1 m/s. When TSV deviated from neutral, lysozyme concentrations decreased, especially when the TSV was [-3, −1.5) (p = 0.01). The S-IgA concentration increased when subjects felt slightly uncomfortable and decreased steadily for further discomfort. The proportion of subjects with decreased immune biomarker levels was minimized in the neutral TSV zone. The findings suggest that under the investigated scenarios, cold draught can suppress respiratory immunity by altering thermal sensations, with effects potentially persisting beyond exposure duration. Ensuring a neutral and comfortable thermal environment is pivotal for maintaining immunity stability. However, more experiments under a wider range of thermal parameters need to be performed to prove the robustness of current results.

Assessing vegetation distribution based on geometrical and morphological characteristics of the urban fabric to provide thermal comfort for pedestrians: A case study in Sanandaj

In previous studies, geometrical aspects of the buildings have been mainly considered in designing of the models, while the impacts of vegetation distribution have not been taken into account. The influence of building geometry on vegetation distribution to create a comfortable thermal environment for pedestrians has not received much attention. An examination of Sanandaj, a city in western Iran, in three fabrics, closed, linear, and open, has been conducted in this study. By using ENVI-met simulator, we studied the orientations, height-to-distance ratio of the buildings, and the geometric shapes of vegetation distributions. There have been two phases to the current research. The first phase includes evaluating the factors that may affect the modeling results in addition to validating ENVI-met software in selected fabrics. A comparison is also made of three model fabrics with and without vegetation in the first phase. The most important environmental factors in this research are air temperature, radiant temperature, wind speed, and physiological equivalent temperature (PET). The results show that there is a positive correlation between orientation and the level of comfort. In a closed fabric, the model with an east-west direction, height ratio of 0.12 and wholly vegetation distribution showed 15.31 % improvement in comfort level compared to the original fabric. The linear fabric with an east-west direction, height ratio of 0.42 and a central vegetation distribution indicated a 22.53 % improvement in the comfort level and in the open fabric, the model with height ratio of 0.75 and the central vegetation distribution improved comfort by 10.42 %.

Thermal comfort evaluation of natural convective-radiant evaporator for air conditioning

The radiant systems come to the fore due to energy saving potential and good integration. The effect of different forms of cold surfaces on human thermal comfort is focused on its application. A novel natural convection-radiant evaporator for heat pumps was developed and its influence on thermal comfort was investigated. A numerical model of the chamber with the evaporator was established and verified with experimental results. Thermal comfort experiments were conducted in a climate chamber and the influence of its asymmetric and uneven cold radiation on the thermal comfort was investigated. Due to the limitation of PMV in uneven radiation situations, the revised predicted mean vote (RPMV) was proposed to assess the thermal comfort in asymmetric and uneven radiation environments based on experimental results. Based on RPMV, the influence of the surface area and temperature of the evaporator on thermal comfort was numerically analyzed. The results indicate that indoor air temperature and relative humidity, RPMV increase with the increase of plate temperature, but decrease with an increase in plate area. The most favourable indoor thermal comfort environment was obtained at an indoor air temperature of 28°C and relative humidity of 50%, which is 2°C higher than traditional air conditioning system.

Development and performance evaluation of intelligent algorithm for optimal control of a hybrid heat pump system during the cooling season

The purpose of this study is to develop a control method for a hybrid heat pump system based on an artificial neural network (ANN) to reduce energy use and create a more comfortable thermal environment. The proposed optimal control method uses an ANN-based predictive model to predict the heat storage tank and indoor temperature during the cooling period and controls the flow rate of the circulation pump on the heat source and load side of the system. The performance of the predictive model for the heat storage tank temperature (R2 = 0.9988; coefficient of variation of the root mean square error [CV(RMSE)] = 1.06 %; normalized mean bias error [NMBE] = 0.16 %; and mean absolute error [MAE] = 0.09℃) and the indoor temperature (R2 = 0.9893; CV(RMSE) = 1.66 %; NMBE = 0.16 %; and MAE = 0.15℃) was excellent. The temperature control of the heat storage tank using the optimal algorithm exhibited an improvement of 18.39 % for the CV(RMSE), 3.10 % for the NMBE, and 1.31 °C for MAE compared with rule-based. For the indoor temperature, the optimal algorithm improved the CV(RMSE) by 1.30 %, NMBE by 0.42 %, and MAE by 0.29℃ compared to rule-based. The energy use was reduced by 52.85 % for the entire system using the optimal control method compared with the existing control strategy under similar outdoor conditions. Using the proposed control method, it is thus possible to improve thermal comfort and reduce carbon emissions in the building sector by improving the control and energy performance of hybrid heat pump systems.

Heat Transfer Mechanisms and Contributions of Wearable Thermoelectrics to Personal Thermal Management

Thermoelectricity can assist in creating comfortable thermal environments through wearable solutions and local applications that keep the temperature comfortable around individuals. In the analysis of an indoor environment, thermal comfort depends on the global characteristics of the indoor volume and on the local thermal environment where the individuals develop their activity. This paper addresses the heat transfer mechanisms that refer to individuals, which operate in their working ambient when wearable thermoelectric solutions are used for enhancing heating or cooling within the local environment. After recalling the characteristics of the thermoelectric generators and illustrating the heat transfer mechanisms between the human body and the environment, the interactions between wearable thermoelectric generators and the human skin are discussed, considering the analytical representations of the thermal phenomena. The wearable solutions with thermoelectric generators for personal thermal management are then categorized by considering active and passive thermal management methods, natural and assisted heat exchange, autonomous and nonautonomous devices, and direct or indirect contact with the human body.

Shading Strategies for Outdoor Waiting Areas in Hot Climates: Improving Thermal Comfort and Healing Environments in the Post-Pandemic Era

Shading Strategies for Outdoor Waiting Areas in Hot Climates: Improving Thermal Comfort and Healing Environments in the Post-Pandemic Era

Fluxo de calor sensível e latente de codornas japonesas mantidas em diferentes ambientes térmicos

ABSTRACT This study aimed to estimate the heat flux through sensitive mechanisms and respiratory evaporation of Japanese quails kept in thermoneutral and warm environments, using simple environmental and physiological measures. 192 nine-week-old quails were used, distributed in a completely randomized design at two temperatures (T1 = 24°C and T2 = 32°C), with 12 replicates of eight birds each, with an experimental period of 63 days, divided into three 21-day periods. Physiological measurements of respiratory rate (RR), cloacal temperature (TC), and body surface temperature (TS) were measured twice a week. The behavior of the energy balance in the climatic chambers was obtained using the total thermal energy exchanges per unit surface area of the birds, derived from the sum of sensible (radiation and convection) and latent heat exchanges. Respiratory rate (P&lt;.0001), surface temperature (P&lt;.0001), and cloacal temperature (P=0.0047) were higher in the 32°C environment. The expired air temperature (P&lt;.0001) and heat loss by respiratory evaporation (P&lt;.0001) showed higher values when the quails were in an environment of 32°C, while the heat losses by convection (P&lt;.0001) and radiation (P&lt;.0001) were higher in a thermal comfort environment. In Japanese quails kept in a controlled environment, sensible heat dissipation by convection is the main way to eliminate excess thermal energy, when the air temperature is up to 32ºC.

Local Thermal Comfort and Physiological Responses in Uniform Environments

The thermal perception of different body parts can vary greatly throughout the human body and have different influences on overall thermal sensation and comfort. Various personal comfort systems (PCS) have been developed to stimulate local body parts for the purpose of enhancing human thermal comfort, yet the most effective body parts for intervention remain undetermined. Therefore, a series of climate chamber experiments under five uniform environments with three sets of suits were conducted in this study. The results showed that the head, chest, belly, and hands tended to feel no cooler than overall in cooler environments, but arms and legs felt generally no warmer than overall in warmer environments. The head, trunk and upper arms were more likely to be the comfort-dominant body parts. Additionally, the upper arms and upper back expected temperature regulation measures the most under non-neutral environments, thus they seem to be the two most needed and effective targeted body parts that a PCS could be applied to. The skin temperature and thermal sensation of limbs were more sensitive to indoor air temperatures than those of the torso. However, variations in the skin temperature of the head, chest, upper back, and calves had the strongest correlation with overall sensation vote changes. The above results and conclusions can not only serve as the basis for the future studies of local thermal comfort, but also provide theoretical guidance for the design of future PCS products.