A Method to Optimize Dormitory Environments Based on Personnel Behavior Regulation

Abstract

With the development of the economy, the indoor environment of college dormitories has received significant attention. This study focused on the problems of high population densities and poor indoor environments in Chinese dormitories. CO₂ and formaldehyde concentrations were measured using field tests and satisfaction was investigated using a questionnaire. In this study, a questionnaire survey was conducted on the indoor environment of student dormitories. The results demonstrated that poor indoor air quality was a common occurrence in student dormitories. The students proposed several improvement measures, including increasing the number of window openings and using mechanical ventilation. This study conducted real-time monitoring of indoor and outdoor CO₂ concentrations at night when students were asleep. The results demonstrated that when the windows were closed, indoor CO₂ concentrations could exceed 3000 ppm, while when the windows were fully open, the indoor CO₂ concentration was about 500 ppm. Formaldehyde concentrations in the dormitory were measured after the windows had been closed for more than 12 h. Additionally, the air exchange rates—calculated based on the tracer gas method—ranged from 0.034 to 0.395, with the smallest value observed when the windows were completely closed and the largest value observed when the windows were completely open. Based on the above conclusions, a window-opening mode was proposed that considers the Chinese students’ routine. This pattern could satisfy the indoor thermal comfort needs in winter as well as improve indoor air quality.

1. Introduction

Globally, individuals spend about 88–92% of their entire time in an indoor environment [1]. In 2023, the number of Chinese college graduates exceeded 10 million people [2]. The college dormitory is where college students spend most of their living and studying time. However, university dormitories are characterized by a high density of people in the spatial environment, a small area per capita, and insufficient ventilation [3]. As centralized air-conditioning systems are rarely used in university dormitories, ventilation through open windows and split air conditioners are generally the most common air exchange methods used in dormitories [4].

Dormitories are essential living and resting places for university students, especially at night. As a special indoor environment, a dormitory is characterized by simple furniture, a large amount of electronic equipment, small spaces, concentrated activity time, and typically a lack of adjustment measures to improve the indoor environmental quality (IEQ) [5]. Without adequate ventilation and an emphasis on ventilation, occupants residing in dormitories for a long time can experience some health problems. It was found that ventilation can be inadequate in dormitories [6], indoor CO₂ concentrations usually exceed the IAQ standard, and current ventilation rates are insufficient to provide enough fresh air in student dormitories. An inadequate ventilation rate might have an impact on the physical health of college students, including complications such as SBS and respiratory system syndrome [7]. Additional studies found that the concentration of TVOC in a dormitory was higher than 0.6 mg/m³, which exceeded the Chinese indoor environmental and WHO standards [8]. A high concentration of TVOC might cause some health problems. There are also studies showing that inadequate ventilation in dormitories increases the incidence of some respiratory infections [9]. In recent years, with the rampant spread of COVID-19, influenza A and B, and other related respiratory viruses, the guidance of ASHRAE suggested an increase in the air exchange rate [10]. Research has shown that dampness has a significant risk association with common colds and influenza, especially in combination with a low ventilation rate [11], which causes viruses to survive and spread more easily indoors. At the same time, a lower ventilation rate is associated with an increased risk of common colds [12]. Therefore, in a densely populated environment where many people share a room, it is necessary to increase the ventilation rate.

In recent years, there has been increasing interest regarding the impact of natural ventilation on indoor air quality (IAQ). Ventilation does not directly affect occupant health or perception outcomes, but the rate of ventilation affects indoor environmental conditions, including air pollutant concentrations that, in turn, may modify the occupants’ health or perceptions [13]. Consequently, the study of airflow patterns under natural ventilation and their impact on the thermal environment is a crucial aspect of scientific designs for dormitory environments. The research on ventilation rates has different emphases. For instance, in China, Zhang et al. measured the ventilation rates of dormitories and offices in a university using the CO₂ tracer gas method and determined the effect factors, such as air conditioners. Yang et al. [14] conducted a series of simulation studies, analyzed the distribution law of wind speed in a student dormitory based on the CFD simulation technique, and put forward a concrete direction to improve the natural ventilation of a dormitory. Li et al. [15] considered the influence of corridor and balcony factors on natural ventilation as well as the indoor thermal comfort of dormitories, and enriched the research on using natural ventilation to improve the indoor environment quality of inner-corridor-type student dormitories in winter. Lei et al. [16] analyzed the influence of indoor oxygen (O₂) concentrations, thermal comfort, and relative humidity on the indoor environment of a dormitory and determined the subjective feelings of the residents using a questionnaire survey. This resulted in an optimized window-opening method. In global research, Diane Bastien et al. [17] examined the effects of real-time CO₂ awareness on the behavior and ventilation rates of student dormitory occupants. Mariya Bivolarova et al. [18] investigated the effects of real-time CO₂ concentrations, temperatures, and humidity on the sleep efficiency of occupants. Paula Brumer Franceschini et al. [19] studied the effect of different behaviors of personnel on ventilation rates. In conclusion, natural ventilation has a natural advantage to improve IAQ, indoor thermal comfort, and energy conservation. However, the ventilation volume of natural ventilation is not controlled and the ventilation effect is unstable, discontinuous, and significantly affected by environmental factors. The above studies established a variety of models to analyze the influence of different factors on natural ventilation and IAQ to optimize the defects of natural ventilation, which are all conducive to the scientific regulation of dormitory indoor environments.

Because of the small indoor space and large number of people in a dormitory, airflow organization is important for the circulation of pollutants and fresh-air inhalation, so improving the indoor airflow organization is one of the key steps to improve the indoor environment of a dormitory [20]. As most of the existing dormitories in China lack fresh-air systems for ventilation, natural ventilation through windows remains the main method to improve indoor air quality and regulate indoor thermal comfort [21]. Using a CFD simulation method, it was concluded that different exhaust systems, different exhaust volumes, and different pollutant source locations could be used to reduce pollutant concentrations [22]. Through the dynamic simulation and analysis of wind environments and the energy consumption of buildings using computer software, it was concluded that the wind environment could be affected by the orientation of a house and the habits of the occupants [23]. In order to fully reflect IAQ, a subjective survey was conducted in the form of a questionnaire [24]. The questionnaire survey showed that the indoor air quality of student dormitories needed to be improved, and could be achieved by increasing the ventilation volume using mechanical systems. Mechanical ventilation systems are more reliable, controllable, and comfortable than natural ventilation through windows [25].

Generally, there are various methods that people can use to improve IAQ, such as opening doors and windows, using air purifiers, etc. These methods have an effect, but they have some drawbacks. Opening windows is a representative act of the occupants. In the case of a good outdoor air environment, opening windows is conducive to improving indoor air quality as well as the indoor environment. However, under certain conditions (such as high outdoor particle concentrations and extreme weather), window-opening is not appropriate [26]. The rate of natural ventilation with fenestration is also inconsistent [27]. In addition, it is difficult for people to perceive the indoor environment [28] and the behavior of opening windows is related to the outdoor temperature [29], which leads to people not always opening windows when the outdoor environment is at its best. The window-opening time also has an effect on the rate of improvement for the indoor environment. After 30 min of window-opening, the effect of the window area on indoor CO₂ levels decreases [30].

In addition to relying on natural ventilation, mechanical ventilation and the installation of air purification systems such as window ventilators and air purifiers can also be used to improve the indoor thermal environment. Window ventilators and air purifiers can effectively improve indoor air quality, but the speed of improvement is not fast enough [31].

This study aimed to address the issues of a low air exchange rate and inadequate ventilation in college dormitory environments. We propose a regulation method for dormitory environments based on personnel behavioral patterns to enhance comfort, improve student satisfaction, and safeguard health. Specifically, it involved measuring CO₂ levels inside and outside student dormitories under different conditions [32] to analyze the air exchange rate (ACH in dormitories. Additionally, we explored the thermal environment and indoor air-quality differences at different orientations and positions within the dormitory under natural ventilation as well as the impact of the window-opening area and duration on the thermal environment. Furthermore, we investigated feasible strategies to improve indoor environments during hot summers and cold winters [33]. This research contributes to increasing ventilation. Moreover, it promotes both physical and mental health among students while enhancing learning efficiency and reducing incidences of upper respiratory tract infections (URIs) and mental health (MH) disorders.

2. Method

2.1. Questionnaire Setup

In the ASHRAE standard, the definition of human thermal comfort is the conscious state of people’s satisfaction with the thermal environment [34]. There are two main factors that affect human comfort: environmental and human [35,36]. Therefore, the questionnaire referred to the student dormitory of Sichuan University as an example to investigate students’ satisfaction with the dormitory environment.

In this study, undergraduate students from all academic levels at Sichuan University were selected as survey respondents. A total of 400 valid questionnaires were received. This study aimed to investigate the satisfaction of college students with the dormitory environment, and was divided into the following two aspects: the evaluation of the apartment and roommate habits; and the apartment temperature, humidity, air quality, and other indicators (Figure 1). The questionnaire comprised 21 questions and is available in the Supplementary Materials. The questionnaire was used as a research tool to understand the current situation of the college students’ dormitory environment to improve the dormitory environment.

2.2. Investigated Cases

The objective of this study was to investigate the effect of window-opening behavior patterns on the indoor environment. To this end, the air exchange rates were tested based on different window openings. The window openings were categorized as closed, 10 cm, 20 cm, 30 cm, and 60 cm when the window was fully opened. The limit hole was located at 30 cm and the window-opening angle was 180°. The indoor and outdoor CO₂ concentrations were simultaneously measured under different working conditions and air exchange rates were calculated according to the real-time CO₂ concentration changes. Additionally, the CO₂ concentration changes in the student dormitory were monitored over the course of a day to observe the concentration changes based on students in their normal state of life.

At the same time, the indoor formaldehyde concentration was monitored after the window was closed for 12 h. Ventilation treatments were then carried out with different window-opening degrees (namely, 10 cm, 30 cm, and a fully open window). Every 5 min, the indoor formaldehyde concentration was detected and, at the same time, the outdoor concentration of different-facing rooms was monitored. An I/O calculation was also carried out.

2.3. Experimental Setup

2.3.1. Geometry of the Dormitory

Our investigation site was located in the student dormitory of Sichuan University (latitude 30°33′25″ N; longitude 103°59′17″ E). The dormitory consisted of three small dormitory rooms and a living room. Rooms A and B were oriented north–south, while room C was oriented east–west. Each dormitory was approximately 16 m² in size and contained 4 students, with a per capita occupancy of approximately 4 m² per student (Figure 2). The diagram below shows the floor plan of the dormitory where the experiment was conducted. The indoor instruments were located in the middle of the room, as indicated by the asterisks in the figure. The outdoor instruments were placed about one meter away from the room. In accordance with the Chinese National Standard GB/T18883-2022 [37], CO₂ was sampled at a height of approximately 0.5 m. Given that the room area was less than 25 m², it was recommended that we set one sampling point in the middle of the room. The experiment was initiated during the winter months of December and January in four student dormitories, two of which were oriented east–west and two of which were oriented north–south. It is noteworthy that all student dormitories utilized split air-conditioning units as the sole heating and cooling system. During the experiments, no air-conditioning units were employed to heat the student dormitories and no alternative heating apparatus was available.

2.3.2. Tracer Gas (CO₂) Setup and Instruments (Figure 3)

Principle of Calculating the Air Exchange Rate in a Room

We used CO₂ as a tracer gas to measure the number of indoor ventilations using the following formula [38]:

$$∆c=\frac{∆t}{V}[FR-nV\left(C_i-C_o\right)]$$

(1)

We ascertained the time when the air exchange rate was more stable and solved the equation to obtain the air exchange rate, n.

In the formula, c represents the change in CO₂ concentration over a period of time, V represents the volume of the dormitory, FR represents the amount of CO₂ released by the human body, and n represents the number of ventilations.

Figure 3. Images of the equipment used to measure CO₂ and formaldehyde.

Figure 3. Images of the equipment used to measure CO₂ and formaldehyde.

Calculation of the Human CO₂ Release FR

$$FR=RQ\frac{0.00056028\times H^{0.725}\times W^{0.425}\times M}{0.23\times RQ+0.77}$$

(2)

where H represents height in m, W represents weight in kilograms, M represents the metabolic rate in W/m² and RQ represents the respiratory quotient with a value of 0.83 [39].

It is important to note that although the CO₂ measurement instrument had a range of 0–10,000 ppm, the sensor used for real-time monitoring had a range of 0–2500 ppm (

Table 1. Parameter of the instruments.

Model	Measuring Variable	Range	Accuracy	Resolution
Performance: CO2 Channel	CO2 Concentration	0–10,000 ppm	±50 ppm	±1 ppm
Performance: Temperature Channel	Temperature	Display: 32 to 122 °F (0–50 °C)	±2 °F (±1 °C)	0.1 °F (0.1 °C)

).

2.3.3. Pollutant Detection

According to the standard, when a dormitory area is less than 25 m², the formaldehyde sampling point should be located in the middle of the dormitory and the sampling height should be about 1.2 m. To obtain the average formaldehyde concentration, 5 samples should be taken under different sampling conditions. We used a PPM-htV as a sample collector (

Table 2. Parameters of the formaldehyde detection device.

Model	Measuring Variable	Range	Accuracy	Resolution
PPM-htV	Formaldehyde Concentration	0.00–10.00 ppm	2%	±0.01 ppm

).

3. Results

3.1. Questionnaire Results

In this survey, (Saying the Supplementary Materials) a total of 400 undergraduates from Sichuan University participated in our investigation, including 211 males and 189 females. Specifically, there were 115 in the first grade, 207 in the second grade, 51 in the third grade, 17 in the fourth grade, and 8 in other grades. Of the participants, 147 lived in a dormitory facing south, 98 lived in dormitories facing north, 62 lived in dormitories facing southeast, and 36 lived in dormitories facing southwest (Figure 4).

The results of the questionnaire indicated that over 60% of the respondents reported that their dormitories were consistently humid throughout the year. Furthermore, 30% of the students stated that the walls of their dormitories were moldy or peeling due to the high humidity levels. More than 80% of the people were in the habit of opening windows during the four seasons, but because it was too cold in winter, the proportion of people opening windows slightly decreased. In addition, more than half the people thought that a single ventilation frequency of more than an hour made the environment more comfortable. However, only 23% of the students chose full window ventilation, so the effect of window ventilation was not particularly ideal and new measures were still needed to improve the indoor air environment (Figure 5 and Figure 6).

3.2. Results of the Dynamic Processes of CO₂

The daily routines of students residing in dormitories with varying orientations were largely similar and there was no discernible correlation between the room orientation and occupant behavior. The trend of carbon dioxide fluctuations was comparable across different orientations; thus, the subsequent findings were based on a north–south orientation of the student dormitories. With the windows fully open, the indoor CO₂ concentration was basically maintained at about 600 ppm at night and the outdoor CO₂ concentration level was about 500 ppm, at which time the indoor fresh-air volume was adequate (Figure 7a). The CO₂ concentration was between 650 ppm and 750 ppm before 12:00 p.m. at night, which was higher than the CO₂ level from 0 to 6:00. The relatively high level of CO₂ during this time was caused by the fact that students were still active during this time. Following the 12 h period, students entered a state of sleep. During this period, the CO₂ emission rate remained relatively stable, resulting in a CO₂ concentration of approximately 600 ppm, which is considered to be optimal for human comfort.

When the windows were fully closed, the indoor CO₂ concentration gradually increased, reaching levels exceeding 2500 ppm. At this time, the indoor fresh air was extremely inadequate (Figure 7b). During the period when the windows were closed, there was a significant limitation in the exchange of fresh air between the indoor and outdoor environments. Consequently, before 12:00 p.m. and during the dormitory personnel’s activities, the indoor CO₂ concentration exceeded 1500 ppm. After 12:00 p.m., the dormitory personnel essentially entered a state of sleep. At this time, due to the indoor environment being in a state of closure, the CO₂ emitted by the students’ respiratory emissions gradually accumulated in the dormitory, resulting in a gradual rise in the level of indoor CO₂, ultimately exceeding 2500 ppm. This level of indoor CO₂ concentration seriously exceeded the standard.

When the window-opening ratio was 1/6, the maximum level of indoor CO₂ was below 1500 ppm and gradually decreased during the night, with an average concentration of about 800 ppm (Figure 8a). Between 11:00 p.m. and 6:00 a.m., the CO₂ concentration level exhibited a decreasing trend. This was attributed to the exhalation of CO₂ by the personnel. The personnel were discharged outdoors in a timely manner; when the personnel were in a deep sleep, the CO₂ produced was more stable. At the same time, the indoor CO₂ basically stabilized at about 850 ppm.

When the window-opening ratio was 1/3, most of the indoor CO₂ concentrations were in the range of 600–800 ppm, which was lower than the indoor CO₂ level in the room with a window-opening ratio of 1/6 (Figure 8b). It was relatively straightforward to ascertain that when the window-opening ratios of 1/6 and 1/3 were the same for the indoor CO₂ concentration trend, the indoor fresh-air volume was greater when the window-opening increased. This was because the overall CO₂ concentration level was at a lower level. When the people were deeply asleep, the CO₂ concentration basically stabilized at 650 ppm, which satisfied the students’ need for a comfortable sleeping environment.

When comparing the four sets of data, it was evident that an increase in the window-opening led to a significant upward trend in the indoor CO₂ concentration (Figure 9). This suggests that proper ventilation is an effective means of creating a conducive sleeping environment. When the window-opening ratio was 1/6–1/3, the indoor CO₂ content met the national standard. However, some studies suggest that to achieve a more comfortable indoor environment, it is necessary to lower the indoor CO₂ concentration. As shown in the figure above, when the window-opening ratio was 1/2, the requirements were met. Concurrently, we discovered that between the hours of 12:00 and 1:00 in the evening, students residing in the dormitory were in the process of transitioning from activity to sleep. During this period, the indoor CO₂ concentration underwent a cyclical pattern of increasing and then decreasing, which correlated with the activity state of the dormitory. Ultimately, as the students fell asleep, the indoor CO₂ concentration level gradually decreased until it reached a stable level.

The length of the dormitory window in its fully open position was 60 cm. The figure below illustrates the trend in the air exchange rate with an increase in the window-opening. As the window-opening increased, the air exchange rate gradually increased (Figure 10). As the window-opening gradually increased, the amount of fresh air entering the room from the outside also gradually increased. This resulted in an increase in the exchange of indoor and outdoor air volumes as well as an increase in the air exchange rate. However, even when the dormitory window was fully open, the indoor air exchange rate remained low compared to standards (

Table 3. Suggested minimum values for air change rates in student bedrooms under different standards.

Standard	ISO	ASHRAE	CEN
Air exchange rate	0.5–1.0	0.5	0.5–1

). This suggests that a combination of natural and mechanical ventilation may be necessary to improve the air exchange rate in students’ dormitories. Concurrently, the opening of windows during winter months when outdoor pollution levels are elevated may result in an augmented concentration of certain particulate pollutants within the room. This phenomenon underscores the necessity for the implementation of mechanical ventilation within the room to fulfill students’ requirements for adequate airflow.

3.3. Formaldehyde Concentration Levels

The initial concentration represented the indoor formaldehyde concentration with the window closed for more than 12 h. In most cases, the concentration exceeded 0.1 mg/m³, which is a greater threat to human health. The degree of window-opening was directly proportional to the speed of the formaldehyde concentration reduction. We recommend ventilating for at least half an hour to achieve a concentration of 0.06 mg/m³ or lower. To achieve an indoor formaldehyde concentration of 0.03 mg/m³ or lower, it is necessary to increase the ventilation time to one hour or longer (Figure 11).

Following the closure of the window for 12 h, the indoor formaldehyde concentration in the dormitories facing north and south was observed to be generally higher than in the dormitories facing east and west. Following 30 min of ventilation, the formaldehyde concentration in the dormitories facing east and west was observed to have reduced to a level comparable to that outside, while the formaldehyde concentration in the dormitory facing north and south was observed to have reduced, but still remained above that outside (Figure 12). When the indoor formaldehyde concentration was equal to the outdoor concentration, it indicated that the indoor pollutants had been sufficiently diluted and that the outdoor air had mixed with the indoor air. The specific time required to achieve sufficient mixing varied with different window openings. For the north–south-oriented student dormitories, it took between five and ten minutes to fully mix outdoor with indoor air under a full window-opening. When the window-opening ratio was 1/2, the time required for indoor and outdoor air mixing was longer than 30 min. When the window-opening ratio was 1/6, the indoor/outdoor formaldehyde concentration ratio I/O was 2 after 30 min of ventilation. For east–west-oriented student dormitories, it took between five and ten minutes to fully mix outdoor with indoor air under a full window-opening. When the window-opening ratio was 1/2, the time required for the indoor and outdoor air to mix was 30 min. When the window-opening ratio was 1/6, the indoor/outdoor formaldehyde concentration ratio I/O was 1.5 after ventilation for 30 min. In contrast, it was relatively straightforward to ascertain that the I/O of the east–west-oriented room declined at a faster rate. This outcome was contingent upon outdoor meteorological parameters, including wind speed and solar radiation intensity.

4. Discussion

In this paper, the indoor air environment of university dormitories was studied from both objective and subjective perspectives. Using a questionnaire survey, we learned the basic conditions of the dormitory environment, such as temperature and humidity, and calculated the air exchange rate by measuring the indoor and outdoor real-time CO₂ concentrations. Concurrently, we quantified the formaldehyde concentration in indoor air under varying window-opening conditions. Our findings revealed that an accumulation in the window-opening time led to a gradual increase in the formaldehyde concentration, potentially compromising the health of dormitory students. Conversely, we also assessed the indoor formaldehyde concentration under different working conditions to assess the impact of the window-opening ratio and ventilation time on the dilution of formaldehyde.

As researchers in various countries have devoted less attention to air quality in student dormitories of universities—where the majority only have split air conditioners installed as the sole air-conditioning equipment—we noted that a novel approach to regulating indoor air quality through the behavioral patterns of personnel could enhance the satisfaction of dormitory students by reducing the indoor pollutant concentration and CO₂ level while satisfying thermal comfort requirements during the winter period.

According to survey data, students may be reluctant to open windows during winter due to excessively cold outdoor temperatures. This behavior results in elevated concentrations of indoor CO₂ and pollutants, posing health risks to students. There is a widespread perception among students that dormitory environments are characterized by high humidity and stuffiness, primarily attributable to inadequate ventilation rates, thereby compromising the occupants’ comfort. To address this issue and enhance ventilation rates to ensure indoor environmental comfort, we propose a novel approach based on the behavioral patterns of occupants.

The data obtained above indicate that our specific personnel behavior regulation method should be as follows. On winter mornings, between 8 a.m. and 12 p.m., the dormitory window should be completely open. At this time, there should be no students indoors and the window should be left open to allow for the thorough mixing of indoor and outdoor air. This not only reduces the concentration of indoor CO₂ to a minimum but also effectively dilutes indoor pollutants. During the period between 12:50 and 1:20 p.m., students may close the dormitory windows. This allows the indoor environment to be ventilated and for fresh air to be introduced to the students during their lunch break. At the same time, curtains could be drawn to minimize the impact of external light and noise on the students. Following the morning period, a 15 to 30 min period of fully opened windows in the room can dilute pollutants in the room. If there are no students in the dormitory in the afternoon, it is recommended that the windows be fully opened to ventilate the room. However, if there are dormitory personnel studying in the dormitory in the afternoon, it is recommended that the windows be opened by 1/6 to maintain the room temperature while providing continuous fresh air.

In the winter months, it is recommended that a window-opening ratio of 1/6 be employed, which simultaneously satisfies human thermal comfort and keeps indoor CO₂ levels low. The image below depicts the temporal evolution of indoor CO₂ and temperature when the window-opening ratio was 1/6. It is evident that the CO₂ concentration was predominantly below 900 ppm, which is below the threshold for adverse health effects on students. Concurrently, the temperature remained within the range of 16.5 °C to 18 °C, which is sufficient to meet the thermal comfort needs of the human body (Figure 13).

Furthermore, we compared the CO₂ concentration in the dormitories of students in a conscious group and an unconscious group after raising their awareness of window-opening. The results demonstrated that after personnel regulated the indoor environment using certain behaviors, the CO₂ level in the room was significantly lower than the CO₂ concentration level in the dormitory of the students in the unconscious group. This indicated that the behavioral patterns had a positive effect on indoor environment regulation, proving the effectiveness of the behavioral regulation measures proposed in this article (Figure 14).

The results of the formaldehyde experiments presented in this paper indicated that the formaldehyde concentration in dormitories with an east–west orientation was lower. This finding appeared to be related to the distribution of the dormitory, rather than the orientation itself. In daily life, the dormitories with an east–west orientation could be ventilated using windows. When the door was opened, the windows in the dormitory contrasted with the windows in the living room. This may have facilitated the ventilation in the dormitories with an east–west orientation as the indoor formaldehyde content was generally lower than the north–south-oriented dormitories. Additionally, we hypothesized that the concentration of formaldehyde inside the east–west-oriented dormitories was lower due to the presence of more plants and trees outside these dormitories.

In winter, due to the low temperatures, many students do not open windows, which results in high levels of CO₂ and pollutants in the room. This article, based on the behavioral model of indoor environment regulation, also provides a direction for students to actively regulate the indoor environment. In contrast to the continuous use of split air conditioners to regulate the indoor environment, our method can effectively reduce energy consumption. However, in the event of necessity, mechanical ventilation must be employed to increase the indoor air exchange rate.

Our study primarily focused on indoor air quality in university dormitories, particularly CO₂ and formaldehyde concentrations, and did not delve into factors such as other indoor pollutants or particulate matter. In addition, although we proposed a window-opening pattern suitable for students’ work and rest schedules to balance thermal comfort and indoor air quality, we did not comprehensively investigate the associated energy use. In addition, our study was limited to a specific geographic location, which may not fully reflect the variations in indoor environmental conditions in different regions or climates.

Future studies could explore the generalizability of our findings to different environments and investigate how changes in climate and building designs may affect indoor air-quality management strategies. In addition, although our study provided valuable insights into the potential benefits of window-opening strategies, more research is needed to further optimize these strategies and evaluate their long-term effectiveness. Future studies could consider conducting controlled experiments to assess the effects of different ventilation methods on indoor air quality, energy consumption, and long-term occupant comfort. In conclusion, although our study contributes to the understanding of indoor air-quality management in college dormitories, there are some limitations that need to be considered. We envision that future research efforts will focus on addressing these limitations by exploring new approaches and developing more comprehensive strategies to improve indoor environmental quality while minimizing energy consumption in different environments.

5. Conclusions

Through this experiment, it was found that the CO₂ concentration level in students’ dormitory rooms without ventilation at night was very high and the amount of fresh air in the room was seriously insufficient. A lower air exchange rate in student bedrooms may result from the presence of window restrictors.

The new regulation method based on personnel behavioral patterns proposed in this study could effectively enhance the air exchange rate and reduce the concentration of indoor pollutants.

Windows that are opened properly for ventilation can effectively improve students’ satisfaction in the dormitory and ensure the health and comfort of indoor personnel.