Effect Of Thermal Environment Research Articles

Evaluating the impact of sky view factor and building shadow ratio on air temperature in different residential and commercial building scenarios: A case study of Beijing, China

The urban building morphology is one of the most important effects of urban thermal environment (UTE). The sky view factor (SVF) is a crucial structure index of buildings and it combines height and density attributes. These attributes have impacts on the air temperature(Tair). However, there are few studies on the association between SVF and Tair across block scales. In this paper, we designed ten scenarios according to the characteristics of Beijing's commercial and residential buildings. Furthermore, we used ENVI-met, a microclimate simulation model, to simulate the Tair in designed scenarios and evaluate the impact of SVF on the Tair of each component. A number of significant observations were noted based on the experimental results: (1) from 10:00 to 17:00, there is a positive correlation between SVF and Tair; from 18:00 to 9:00 the next day, there is a negative correlation between SVF and Tair (2) the relationship between building shadow ratio (BSR) and Tair is not a single negative correlation: at sunrise, BSR is the maximum in a day, but the cooling effect of BSR on Tair is not obvious because of the weak solar radiation. In addition, the arrangement of building directions has a great influence on the relationship between BSR and Tair (3) for the same building scenario, BSR decreases with the increase of SVF (4) the synergistic effect of SVF and BSR on Tair in the daytime can be divided into two periods, the separation time points are 7:00 and 14:00. This study can provide instructions for urban design in optimizing building layout and mitigating the urban heat impact on human health.

Modeling and Free Vibration Analysis of Variable Stiffness System for Sandwich Conical Shell Structures with Variable Thickness

This paper presents modeling and free vibration analysis of variable stiffness system for the truncated sandwich conical shell made of porous aluminum foam core with variable thickness and carbon fiber face sheets under the simply supported boundary condition. The thickness of the core layer varies along the longitudinal direction. Five different types of porosity distribution of the aluminum foam core, which contains Type-X, Type-O, Type-U, Type-V and Type-[Formula: see text] along the direction of thickness, are considered. Considering the effect of thermal environment, we derive the nonlinear dynamic equations based on first-order shear deformation theory and Hamilton’s principle, and obtain the natural frequencies of the system by employing the Galerkin method. The comparison and validation are conducted by contrast with the determined results of the literature. The influences of porosity distribution pattern, porosity coefficient, the total number of layers, temperature increment, semi-vertex angle, the exponent of thickness function, the minimum radius-thickness and length-thickness ratio of the core layer on the natural frequencies, modal and mode shapes are studied comprehensively.

The effect of thermal and cryogenic environments on the impact performance of aluminum-glass fibers/epoxy laminated composites

In this research work, the effect of various environments on the impact properties of fiber metal laminates was investigated. To do so, in the first step, the 2024 aluminum layers were surface modified with the etching method. Then, the various glass fibers/epoxy composites with the configurations of (0°/0°/0°/0°, 90°/90°/90°/90°, +45°/−45°/−45°/+45° and 0°/90°/90°/0°) were sandwiched between two aluminum sheets. In the following, these samples were aged under thermal cycling (between 25 and 100 °C), isothermal aging at the temperature of 100°C, cryogenic cycling (between −196 and 25 °C), and cryogenic isothermal aging at the temperature of −196°C. To understand the effect of various aging methods on the mechanical features of these structures, the Charpy impact test was performed. Also, the failure mechanisms and related phenomena were assessed by visual observations and microstructural investigations. In the first steps of thermal aging, the impact strength of FMLs was improved, which the highest of that being 46.9%. In the higher cycles or exposing times, the impact strength showed reducing trends, due to thermal degradations of the epoxy matrix. The cryogenic cycling in the high cycles reduced the impact strength of FMLs. But in the cryogenic isothermal condition, in some cases, the improvement in the impact strength was seen, which the highest of that being about 43.4%.

Dynamical responses of variable generatrix profile and thickness ceramic-matrix composite shells under electro-thermo-mechanical effects

In this paper, new structures of shells have been proposed with complex profiles and thicknesses varying through the length direction subjected to a thermal environment. The inner and outer surfaces of the shells are bonded to the piezoelectric actuators with changes of various voltages. The nonlinear motion equations of variable generatrix profile and thickness (VGPT) shells are solved to investigate the nonlinear vibration and chaotic responses using the theory of elasticity and Von Karman-Donnell’s geometrical nonlinearity assumption. Four kinds of VGPT shells are combined by two types of complex profiles and two patterns of thickness distribution. The used materials are made of Silicon carbide (SiC) and Borosilicate. Galerkin’s method is applied to solve the systems of differential equations and then the fundamental frequencies and nonlinear dynamic behaviors can be found. The effects of material (coefficient k), geometrical parameters, thickness, piezoelectric layers, and thermal environment on the dynamic responses of VGPT shells are examined and presented in tables and graphs.

CFD Analysis of Solar Greenhouse Thermal and Humidity Environment Considering Soil–Crop–Back Wall Interactions

In the study of solar greenhouses, microclimate, soil, and back walls have an important influence on the greenhouse thermal environment because of their good heat storage and release characteristics. The transpiration of crops makes indoor humidity increase sharply, which is the main factor affecting indoor humidity distribution. Therefore, it is of great significance to grasp the microclimate change law of solar greenhouses and study the coupling effect of thermal and humidity environment. In this paper, based on computational fluid dynamics (CFD), a three-dimensional model of the thermal and humidity environment of a solar greenhouse is established, and the indoor temperature and humidity distribution under the influence of soil, crops, and back walls are considered. The CFD model initialization uses binary fitting functions to fit the temperature distribution of soil, back wall, and air. The distribution law of the temperature field and relative humidity field of the solar greenhouse under three different working conditions is simulated, that is, the insulation is uncovered and the ventilation window is closed during the day (G1), the insulation is uncovered and the ventilation window is opened during the day (G2), and the insulation is put down and the ventilation window is closed at night. (G3). The results show that the simulation results are in good agreement with the actual results under the three working conditions, and this paper can provide a reference for the improvement of the greenhouse structure and environmental regulation.

Experimental study on the effects of exercise intensity and thermal environment on thermal responses

Public exercise facilities have recently emerged across China. This study aims to investigate the impacts of exercise intensity and thermal environment on thermal responses as well as examine the dynamic changes and differences in thermal responses during exercise. Using a controlled thermal chamber, university students were assessed at varying walking speeds under six thermal conditions, from −15 to 35 °C. Their psychological and physiological responses were observed and recorded in real time during the thermal adaption, exercise, and rest phase. Firstly, the exercise intensity significantly affected heart rate and metabolic rate, whereas the thermal environment had no significant effect. The effect of the thermal environment on skin temperature, thermal sensation vote (TSV), and thermal comfort vote (TCV) was more pronounced than that of exercise intensity. Secondly, during exercise, the metabolic rate took 6–9 min to stabilise, and the psychological response lagged compared to the physiological response. Thermal sensation was closest to neutral at 15 °C, 5 °C, and −5 °C when walking at 3 km/h, 4.50 km/h, and 6 km/h, respectively. Thermal comfort vote (TCV) levels were greater for higher exercise intensities at −15 to 5 °C, lower for higher exercise intensities at 25–35 °C, and similar for varied exercise intensities at 15 °C. Finally, current thermal comfort guidelines underestimate the exercise metabolic rate by at least 9.7%. This study helps clarify the dynamic changes and influence factors of thermal responses during exercise and provides a reference for future research on exercisers’ thermal responses.

Free axisymmetric vibrations of heated non-uniform Bi-directional FGM Mindlin rings employing quadrature approaches

The present article investigates the axisymmetric vibrations of non-uniform bi-directional functionally graded rings under two-dimensional temperature distribution on the basis of first-order shear deformation theory. The linear variation of thickness along the radial direction is controlled by a taper parameter. The temperature-dependent mechanical properties are assumed to be graded in thickness as well as radial direction. The separation of variables method is applied to obtain the classical solution of two-dimensional heat conduction equation by imposing the thermal boundary conditions. The governing differential equations of thermoelastic equilibrium and axisymmetric motion together with boundary conditions are extracted from Hamilton’s principle. The quadrature technique is used to obtain the frequency equations and then the lowest three roots of these equations are calculated by MATLAB. After validating the results for the present approach, numerical results are given to analyze the effects of thermal environment, taper parameter, volume fraction index, heterogeneity and density parameters on the frequency parameter. Mode shapes for the specified rings are illustrated.

Plasticity in Na+/K+-ATPase thermal kinetics drives variation in the temperature of cold-induced neural shutdown of adult Drosophila melanogaster.

Most insects can acclimate to changes in their thermal environment and counteract temperature effects on neuromuscular function. At the critical thermal minimum, a spreading depolarization (SD) event silences central neurons, but the temperature at which this event occurs can be altered through acclimation. SD is triggered by an inability to maintain ion homeostasis in the extracellular space in the brain and is characterized by a rapid surge in extracellular K+ concentration, implicating ion pump and channel function. Here, we focused on the role of the Na+/K+-ATPase specifically in lowering the SD temperature in cold-acclimated Drosophila melanogaster. After first confirming cold acclimation altered SD onset, we investigated the dependency of the SD event on Na+/K+-ATPase activity by injecting the inhibitor ouabain into the head of the flies to induce SD over a range of temperatures. Latency to SD followed the pattern of a thermal performance curve, but cold acclimation resulted in a left-shift of the curve to an extent similar to its effect on the SD temperature. With Na+/K+-ATPase activity assays and immunoblots, we found that cold-acclimated flies have ion pumps that are less sensitive to temperature, but do not differ in their overall abundance in the brain. Combined, these findings suggest a key role for plasticity in Na+/K+-ATPase thermal sensitivity in maintaining central nervous system function in the cold, and more broadly highlight that a single ion pump can be an important determinant of whether insects can respond to their environment to remain active at low temperatures.

Static and Dynamic Analysis of Re-Entry Vehicle Nose Structures Made of Different Functionally Graded Materials

High-speed aerospace applications, such as re-entry vehicles, mostly involve thin-walled structural components with a high strength-to-weight ratio and high-temperature resistant. The present novel work comprises the structural and thermal analysis of re-entry vehicle nose structures made of four functionally graded materials (FGM). Four FGM shell structures made of aluminum/silicon carbide, aluminum/aluminum oxide, Ti-6Al-4V/silicon carbide and Ti-6Al-4V/aluminum oxide have been considered for the re-entry vehicle nose. The effect of various thermal environments, as well as the linear temperature rise from metal-rich to ceramic-rich on critical buckling temperature and natural frequency have been studied. The critical buckling temperature, as well as the natural frequency of the large, thin re-entry vehicle nose structures, decrease with an increase in a uniform thermal environment, as well as linear temperature rise. The effect of shell thickness on buckling and dynamic characteristics of an FGM shell is also studied, suiting the nose of the re-entry vehicle under various linear temperature rises. The critical buckling temperature and natural frequency are quantified for several cases, and it was observed that they are significantly influenced by the shell thickness. Thus, the research intends to determine the thickness required for such thin and large shells to withstand in the re-entry thermal conditions.

Investigation into effect of non-uniform thermal environment on thermal sensation under stratum ventilation for heating by using interpolation-based multi-level fuzzy comprehensive evaluation

Stratum ventilation for heating is applied to provide satisfactory indoor thermal environments with great potentials in winter. Indoor non-uniform environments are important for both overall and local thermal sensations in the same occupied subzone (i.e., vertical spaces) as well as different subzones of the occupied zone (i.e., horizontal spaces) under the effect of supply air jets. This study carried out field chamber experiments to consider the effect of non-uniform environments on both overall and local thermal sensations under stratum ventilation for heating using the multi-level fuzzy comprehensive evaluation (MFCE) method. This method has a multi-level structure to simultaneously investigate thermal sensation in both vertical spaces and horizontal spaces. The interpolation models of thermal sensation are helpful to enlarge the experimental sample size investigated by MFCE. The results showed that the interpolation-based MFCE method can quantitatively analyze the effect of non-uniform environments on thermal sensation in different subzones of the occupied zone from vertical spaces and horizontal spaces under the effect of supply air parameters. Compared with supply air temperature, supply air velocity has the opposite influence on the variation range of both integrated thermal sensations of feet, head and overall body and local thermal sensation of feet between the occupied subzones 1 and 2. Supply air temperature and velocity of 25–27 °C and no less than 1.1 m/s were recommended to improve the non-uniformity of thermal environments.

Research on the influence of indoor thermal environment and activity levels on thermal comfort in protective clothing

With the outbreak of infectious diseases such as Corona Virus Disease 2019, medical staff work intensively in isolated plots, medical disposable protective clothing (MDPC) has poor air condition and humidity permeability, which seriously reduces the thermal comfort of medical staff. In this paper, the effect of indoor thermal environment and activity levels on thermal comfort inside MDPC was studied by experiment. Five parts of the body were measured inside MDPC and the appropriate movements were chosen to simulate different levels of labor intensity. Meanwhile, physiological parameters and subjective thermal sensation were statistically analyzed. The results showed the influence range of different indoor temperatures on the temperature and humidity inside MDPC was about 1 °C and 10 %, respectively; it indicated that the environment inside MDPC could be improved by reducing indoor temperature, that is, a cross intelligent adjustment mode was proposed. The effect of labor intensity on the temperature inside MDPC was significantly less than that of humidity. Within 20 min, the humidity changes under moderate and heavy labor intensity were even more than 10 %, and the subjective discomfort threshold of the subjects increased by nearly 50 %. Furthermore, the maximum benefit could be obtained by concentrating cooling on back, forehead, chest and upper arm. Theoretical models of working time, labor intensity, and temperature and humidity inside MDPC under different indoor temperatures and different parts were given. In addition, acceptable regions inside MDPC which were approximately parallelogram in the enthalpy-humidity chart. These conclusions could be a reference for future thermal comfort inside MDPC research.

Study on indoor adaptive thermal comfort evaluation method for buildings integrated with semi-transparent photovoltaic window

Semi-Transparent Photovoltaic (STPV) windows have the potential of active energy-saving and have attracted more attention in recent years. Due to the selective absorption effect of solar cells on solar radiation, the indoor thermal environment and human thermal comfort of buildings integrated with STPV windows are considerably different from that with clear glass windows, and there are few studies on this. In this paper, the indoor human thermal comfort of buildings integrated with STPV window was investigated. Firstly, experiments and subjective questionnaires for the indoor environment were conducted in STPV and clear glass window buildings respectively. Secondly, the influence of illuminance on thermal sensation was statistically analyzed, with the consideration of visual effect, non-visual effect, as well as visual and non-visual coupling effect respectively. On this basis, an innovative thermal comfort evaluation method was provided. The thermo-physiological effect, light-physiological effect and light-psychological effect were comprehensively considered in this method. Finally, the reliability was verified by comparing with TSV. According to tests and questionnaires, it was found that the indoor thermal environment of the STPV window was an uneven thermal environment, and the subjective thermal sensation was more inclined to be slightly warm. When investigating the effect of illuminance on thermal sensation considering visual and non-visual coupling effect, it was found that illuminance had a significant influence on thermal sensation in different illuminance ranges. Meanwhile, it indicated the coupled effect of thermal environment and daylight environment on the thermal comfort of human.

Effect of humid and thermal environments on the performance of an epoxy resin pavement filling joint material

Modified epoxy resins have shown good results for the repair of pavement cracks. However, as the grouting material is directly exposed to the atmosphere, its performance is affected by humid and heat, resulting in a certain deterioration in its performance and service life. To explore the influence of humid and heat on an epoxy resin joint filling material (EPFM), EPFM was treated in humid and thermal environments for varying periods of time in this study, and the water absorption characteristics, mechanical properties, and road performance of the EPFM were tested. The stress relaxation index was used to evaluate the stress relaxation performance of the EPFM after humid and heat treatments. The results show that in a humid environment, EPFM undergoes a three-stage water absorption process, and the increase in water content reduces its glass transition temperature. In low-temperature environments, the tensile and shear strengths of the EPFM are reduced, but the deformation properties are enhanced under different stress patterns. In a high-temperature environment, the internal macromolecular structure of the EPFM is damaged, causing a significant reduction in its toughness. Under the −10 °C test conditions, the tensile strength reaches a maximum of 31 MPa, and the elongation at breaking decreases to less than 60 %. Through stress relaxation tests, it is found that compared with the thermal environment, water further weakens the stress relaxation performance of the EPFM.

Effect of Environmental Temperature on Working Memory in Military Personnel

Background: Working memory is one of the essential cognitive functions. Achieving the highest cognitive performance is especially important in critical jobs such as military and crisis management-related jobs. The thermal environment can cognitive functions. Humans have different thermal sensations in the same fixed temperature environments. Objectives: This study was conducted to determine the effect of thermal environment and thermal sensation on working memory. Methods: Each of 20 male adult participants, physically and mentally healthy aged 19 - 29 years, experienced seven thermal conditions (office room climate: 14°C, 17°C, 20°C, 23°C, 26°C, 29°C, and 32°C) over four months. Before the test, they waited 40 minutes in the room for adaptation. The thermal sensation questions were asked from them, and working memory was measured with the n-back test. Results: In this experiment, 140 working memory data were collected. The relationship between air temperature and working memory was significant in two of six conditions. The relationship between thermal sensation and working memory was significant in all six conditions. Participants had various thermal sensations in the same fixed thermal environment. Conclusions: Thermal sensation significantly affected the working memory of the environment users. Working memory was more related to changes in people’s thermal sensation than changes in ambient temperature. Adjusting the ambient temperature based on the user’s thermal sensation increases cognitive performance and prevents working memory loss.

Low-velocity impact response of cylindrical sandwich shells with auxetic 3D double-V meta-lattice core and FG GRC facesheets

The cylindrical sandwich shells with auxetic 3D double-V meta-lattice core and functionally graded (FG) GRC (graphene-reinforced composite) facesheets are designed, modeled and analyzed to reveal their nonlinear dynamic response when subjected to low-velocity impact. The 3D double-V meta-lattices, developed from the 2D double arrowed honeycombs, are further self-adapted to meet the requirements of the curved space between facesheets of sandwich shells. By means of micromechanical modeling according to the extended Halpin-Tsai model, the temperature-dependent properties are determined for GRC facesheets, which are further designed to possess FG configurations along the radical direction of the shell structures. Full-scale FE modeling and nonlinear dynamic analysis are then carried out. Numerical results reveal the novelty of FG configurations of GRC facesheets, and include the effects of drop-heights, shell lengths, strut radii, shell radii and thermal environments. Present models, including 3D meta-lattice cores and polymer matrix composite facesheets, are believed to provide new thoughts for the design of lightweight sandwich shells and their applications in the fields of ocean engineering.

Effects of thermal environment and external mean flow on sound transmission loss of sandwich functionally graded magneto-electro-elastic cylindrical nanoshell

Similar to many new engineering ideas that are actually interdisciplinary subjects, magneto-electro-elastic (MEE) structures also need accurate ways of describing their structural behaviors. Based on nonlocal elasticity theory, the present article investigates the vibroacoustic behavior of a hollow multilayer cylindrical nanoshell where the core layer is made of isotropic functionally graded material (FGM) and other layers are made of MEE materials. The proposed system also is subjected to combined loads which contain a plane sound wave, the initial external electric and magnetic loads, and external mean airflow. The displacement field of structure is described using the third-order shear deformation assumption (TSDA). The derivation of vibroacoustic equations in the form of coupled relations is realized by implementing Hamilton's principle. The material properties of FGM core layer are supposed to vary along the in-plane and thickness directions based on the power-law model. The final objective is to analyze the sound transmission loss (STL) characteristics of the structure and inspect the accuracy of the developed method against existing data followed by comparing the results in terms of geometric and acoustic parameters. The obtained results and the described method can be used advantageously to better optimize such structures by choosing appropriate initial electric and magnetic potentials, flow Mach number, nonlocal parameter, material gradient index, incident angles.

Nonlinear vibration responses of lattice sandwich beams with FGM facesheets based on an improved thermo-mechanical equivalent model

An investigation on the nonlinear vibration behaviors of a lattice sandwich beam with pyramidal truss core and functionally graded material (FGM) facesheets under thermo-mechanical loads is performed with consideration of the temperature-dependency of material properties. In present work, an improved equivalent methodology is proposed to determine the transverse shear modulus of pyramidal core subjected to a non-uniform thermal field across thickness direction and makes lattice truss core transformed to a continuous layer. Finally, the lattice sandwich beam is modeled as a three-layered sandwich structure. The facesheets are made of FGMs with mixture of ceramics and metals in a pow-law form. The outer surfaces of facesheets are ceramic-rich, while the inner surfaces are metal-rich. The nonlinear strain–displacement relations are established based on the von Kármán large deflection and classical beam theory. The Lagrange method are implemented to yield equations governing the free and forced vibration behaviors. With the help of Newton-Raphson iteration technique as well as the Newmark-β method, the nonlinear time-independent responses of the sandwich beam under thermal environment are solved. A comprehensive parameter study is directed to address the effects of non-uniform thermal environment, FMG facesheets, external load, and lattice core on the nonlinear vibrations of the beams.

Urban thermal environment effects based on visual indices: A case study in Xuzhou City, China

Urban thermal environments are closely related to habitats, citizens' health, and sustainable development. Based on green view index (GVI), we proposed two new visual indices, construction view index (CVI) and imperious surface view index (R&PVI). Mobile observation was used to obtain urban thermal environment data, images and coordinates synchronously in Xuzhou City in late summer, including urban area (U), scenic area (S), exterior of university campus (E), and university campus inside (CUMT). We analyzed the impacts of the urban composition represented by the visual index on the urban thermal environment. The results showed that, along the sampling line, mean air temperature (Ta) was highest (30.42 ℃) and mean relative humidity (RH) was lowest (40.7%) in urban area, while mean Ta was lowest (29.35 ℃) and mean RH was highest (48.4%) in scenic area. The situation of mean wind-chill temperature (TaW) was the highest (32.95 ℃) in the urban area and the lowest (31.93 ℃) in the scenic area. As for CVI, urban area, university campus inside, exterior of university campus and scenic area ranked in descending order, while GVI showed an opposite pattern. CVI was significantly positively correlated to Ta and TaW, but negatively to RH. GVI was significantly negatively correlated to Ta and TaW, but positively to RH. R&PVI was significantly positively correlated to Ta and TaW, but not correlated to RH. CVI and GVI influenced Ta significantly, with the independent effects being 10.4% and 18.9%, and joint effects being 7.8% and 11.3%, respectively. As for RH, CVI and GVI contributed significantly as well, independent effects were 37.5% and 15.7%, and joint effects were 51.4% and 30.2%, respectively. As for TaW, the three visual indices contributed significantly, but independent and joint effects were lower than those on Ta. Moreover, visual indices contributed more on RH than Ta or TaW. The results could provide ideas for optimizing urban thermal environments and mitigating urban heat island effects, and have practical implications for urban renewal and improvement of the quality of human living environment.

Investigation of mechanical properties of PVA fiber-reinforced cementitious composites under the coupling effect of wet-thermal and chloride salt environment

In this study, the mechanical properties of polyvinyl alcohol fiber-reinforced cementitious composites (PVA-FRCC) under the coupling effect of wet thermal and chloride salt environment were investigated through a series of experiments, including compressive strength, flexural performance, elastic modulus, three-point bending fracture, and scanning electron microscope (SEM) tests. An environmental simulation test chamber was used to simulate the wet-thermal and chloride salt environment, in which the parameters of temperature, relative humidity (RH), mass fraction of the NaCl solution, and action time were determined to be 50 °C, 100%, 5%, and 30 d, respectively. The volume contents of the PVA fibers incorporated in the cementitious composites were 0, 0.3%, 0.6%, 0.9%, 1.2%, and 1.5%. The results indicated that the mechanical properties of the cementitious composites decreased after being subjected to the coupling effect of the wet-thermal and chloride salt environment. The incorporation of the PVA fibers improved the mechanical properties of the cementitious composites under the coupling effect of the wet-thermal and chloride salt environment. When the addition content of PVA fiber was approximately 0.6–0.9%, the mechanical performance of PVA-FRCC was the best. Compared with the cementitious composite without fibers, the maximum growth rates of the cube, axial and residual compressive strength, elastic modulus, and flexural strength of the PVA-FRCC under the coupling effect of the wet-thermal and chloride salt environment owing to the addition of PVA fiber reached 29.96%, 46.92%, 29.71%, 46.15%, and 67.06%, respectively. In particular, the 1.5% PVA fiber dosage increased the initiation and unstable fracture toughness, and fracture energy by 145.57%, 333.01%, and 2656.38%, respectively.

Thermal Environment and Thermal Comfort in University Classrooms during the Heating Season

In recent years, there has been increasing concern about the effects of indoor thermal environments on human physical and mental health. This paper aimed to study the current status of the thermal environment and thermal comfort in the classrooms of Northeastern University during the heating season. The indoor thermal environment was analyzed with the use of field measurements, a subjective questionnaire, regression statistics, and the entropy weight method. The results show that personnel population density is an important factor affecting the temperature and relative humidity variations in classrooms. The results also show that the temperature and relative humidity in a lecture state are respectively 4.2 °C and 11.4% higher than those in an idle state. In addition, in university classrooms in Shenyang, the actual thermal neutral temperature is 2.5 °C lower than the predicted value of the Predicted Mean Vote. It was found that increasing indoor relative humidity can effectively improve the overall thermal comfort of subjects. Furthermore, the temperature preference of women was higher than that of men. Therefore, when setting the initial heating temperature, the personnel population density and sufficient indoor relative humidity have been identified as the key factors for improving the thermal environment of the classroom.