Thermal Comfort Research on the Rural Elderly in the Guanzhong Region: A Comparative Analysis Based on Age Stratification of Residential Environments

Abstract

Addressing the thermal comfort of the elderly is a pressing concern amidst the escalating aging population in rural China. This study presents a comprehensive assessment of the thermal comfort within traditional and self-built dwellings in the Guanzhong region. Utilizing a mixed-methods approach encompassing both on-site measurements and questionnaire surveys, with a novel approach of segmenting the elderly population into three distinct age groups. The findings indicate that: (1) An average clothing thermal resistance of 1.83 clo among the elderly, which was found to be relatively higher when compared to other areas and positively correlated with age; (2) A thermal neutral temperature of 8.46 °C for traditional dwellings and 10.53 °C for self-built dwellings, both of which were lower than anticipated, indicating a discrepancy between current living conditions and elderly residents’ thermal expectations; (3) A positive correlation between age and the preferred neutral temperature, with the elderly showing a preference for warmer indoor environments. Additionally, we propose targeted strategies to enhance the thermal comfort of the elderly across different age groups and dwelling types. This study refines the thermal comfort evaluation system for the elderly in China’s cold climate regions, offering theoretical insights and practical guidance for the renovation of rural dwellings and the improvement of elderly living standards in the Guanzhong area.

1. Introduction

1.1. Background

With the rapid development of global population aging, the elderly population is projected to account for 23.8% and 32.8% of the total population by 2030 and 2050, respectively [1]. In China, the degree of population aging has also significantly increased, with the proportion of elderly rising from 4.4% in 1953 to 14.2% by 2021 [2]. According to the 2020 China National Census, the proportion of the rural population aged 60 and above and 65 and above is 7.99% and 6.61% higher than that of urban areas, respectively [3]. Research indicates that due to the gradual decline in physical and health conditions, elderly people spend about 80% of their time indoors [4,5]. The indoor environment is directly linked to the health of the elderly [6,7]. For the elderly, housing needs must transition from mere survival to comfort and livability [8]. As age increases, the metabolic rate of the elderly decreases and their ability to regulate body temperature declines [9,10,11]. Long-term exposure to cold conditions can lead to hypothermia, posing specific health risks [12]. Research has consistently shown that the thermal perception of the elderly significantly differs from that of the general population, and their thermal comfort needs change over time [13,14]. There is also a systematic gap between the elderly’s perception of comfort standards and the actual standards [15]. Additionally, the thermal needs of elderly people vary with age. Previous research found that the thermal preference temperature for the elderly aged 80 and above is 1.5–2 °C higher than for those aged 60–79 [11]. Therefore, it is necessary to explore the thermal comfort differences among elderly people of different age groups. China has a vast territory, and the thermal comfort requirements of the elderly vary significantly across different climate zones and living conditions [16,17,18,19]. Research indicates that in rural dwellings in Qiqihar, all surveyed homes exhibited issues such as window drafts and poor performance of the building envelope, with over 50% of family living rooms having temperatures below the thermal neutral temperature [20]. In regions like Henan and Xinjiang [21,22], rural dwellings can be categorized into two main types: those primarily constructed with rammed earth and those with brick-concrete structures. These dwellings typically do not use insulation materials, and wooden windows [23] and wooden door frames [23] remain predominant in certain regions. Rural dwellings have serious insulation problems and significantly lower airtightness compared to urban houses [24]. Therefore, when studying the thermal comfort of elderly people of different age groups, it is essential to conduct a classification analysis of different types of rural dwellings in these regions to understand their impact on the health and well-being of the elderly population.

According to the results of the Seventh National Population Census of Shaanxi Province [25], the population aged 60 and above is nearly 7.6 million, accounting for 19.2% of the province’s total population, which is higher than the national average. The degree of aging has been deepening continuously. Over the past decade, the proportion of the population aged 60 and above in Shaanxi Province has increased by 6.35 percentage points, which is also higher than the national average growth rate. Among them, the proportion of the population aged 65 and above has increased by 4.79 percentage points. In terms of regions, the proportion of the elderly population aged 65 and above in cities such as Baoji, Weinan, and Xianyang, located in the Guanzhong region, all exceed 15%. These data indicate that the aging problem in the Guanzhong area is quite severe, directly affecting the residential comfort and quality of life of the elderly residents in the region. Therefore, this research focuses on the thermal comfort needs of the elderly in this area, aiming to provide a scientific basis and practical guidance for improving their living environment.

1.2. Age Segmentation of the Elderly

A literature review reveals that some scholars have studied the age segmentation of the elderly, finding significant differences in their physical health status. For example, Irish scholars divided the surveyed elderly individuals into five age groups: 65–69, 70–74, 75–79, 80–84, and 85+, and their analysis and predictions indicated that individuals aged 85 and above are more prone to hip fractures [26]. Other studies segmented the elderly into three age groups: 60–64, 65–69, and 70+ years, predicting differences in the incidence rates of breast cancer among different age groups [27]. Additionally, some researchers proposed different health service strategies based on the varying physical conditions of elderly people in different age groups. For instance, one study divided the elderly in Hebei Province into three age groups: 60–69, 70–79, and 80+ years, and formulated targeted health support strategies [28]. Research on elderly people in rural areas of Jiangsu Province found differences in the demand for home-based care services among the 60–69, 70–79, and 80+ age groups and proposed appropriate development strategies [29]. The Law of the People’s Republic of China on Protection of the Rights and Interests of the Elderly [30] and the World Health Organization (WHO) [31] have also suggested age segmentation for the elderly, further indicating the necessity to explore the differences in thermal perception and comfort preferences related to age [32,33]. Studies analyzing the thermal environment sensitivity of elderly people have found that the age groups 60–69, 70–89, and 90–99 are optimal for segmentation [33]. This study refers to the relevant age segmentation in previous research, using a 10-year interval to divide the subjects into different age groups and comparing them with previous studies (as shown in

Table 1. Comparison of age groups.

Organization	Age Group
Law of the People’s Republic of China on Protection of the Rights and Interests of the Elderly	45–59; 60–89; 90–99; 100
World Health Organization	44; 45–59; 60–74; 75–89; 90+
Other research	60–69; 70–89; 90–99
This study	60–69; 70–79;80–89

). The age groups in this study are consistent with authoritative research results. Based on the thermal physiological functions of the elderly and current survey conditions from previous studies, some age intervals were adjusted.

1.3. Literature Review of Thermal Comfort for the Elderly

Numerous studies have been conducted on the thermal comfort of the elderly, focusing primarily on the following aspects:

1.3.1. The Impact of Age on Thermal Comfort

Comparative studies between the elderly and younger individuals have found that people aged 71–76 are less sensitive to thermal environments than those aged 21–30 [34]. Compared to younger individuals, the elderly prefer higher indoor temperatures. Hong Kong scholars compared the thermal acceptability differences between elderly residents in elderly centers and younger residents. The results showed that for people aged 60 and above, the predicted mean vote decreases approximately every 25.3 years [11]. Subjective questionnaire studies have found that elderly individuals who have lived in the same location for a long time adapt better to the same indoor thermal environment [35,36].

1.3.2. Regional and Urban-Rural Differences

In recent years, many Chinese scholars have investigated the thermal comfort of the elderly in different climate zones in China, which can be divided into the Severe Cold Zone (SC), Cold Zone (CZ), Hot Summer and Cold Winter Zone (HSCW), Hot Summer and Warm Winter Zone (HSWW), and the Temperate Zone (TZ). For example, the winter comfort temperature range for the elderly in Hunan (Hot Summer and Cold Winter climate zone) is 16.7 °C to 27.1 °C [37]. In the cold climate zone, Yuan et al. found that the indoor temperature of Tianjin has a significant impact on the health and comfort of the elderly, and the neutral temperature for elderly residents is 16.74 °C [38]. The acceptable average indoor temperature for rural elderly people in Beijing is 14.6 ± 3.3 °C [39]. Additionally, scholars compared the winter neutral temperatures of rural nursing homes in different climate zones (Qiqihar and Shanghai), finding significant regional differences in the adaptability and sensitivity of rural elderly people to temperature [40].

Due to the poor thermal performance of rural dwellings, studies indicate that urban elderly residents are more satisfied with their living conditions due to better indoor thermal environments and a variety of thermal adaptation measures [18]. However, the thermal neutral temperature in rural dwellings often falls below the comfort range, such as the 14.4 °C observed in Shandong rural dwellings during winter [19], and Tibetan residents’ actual thermal neutral temperature is lower than predicted [16,17]. The indoor temperature in cave dwellings in rural Shaanxi does not meet the thermal needs of the elderly [41]. Despite facing lower indoor environments, elderly residents in rural Heilongjiang do not feel uncomfortable due to their strong adaptability to lower temperatures and lower thermal expectations. In a comprehensive review of the thermal environment of rural dwellings in China, Zhang et al. pointed out that rural residents have a higher tolerance for indoor low temperatures and lower thermal comfort requirements. However, they also noted that there is still a lack of detailed research on the thermal preferences of elderly people of different age groups and their living environments in rural areas [42].

1.4. Research Gaps

Through the above literature review and comparative studies (

Table 2. Summary of study on rural indoor thermal comfort of different climate zones.

Climate Zone	Ref.	Season	Comparison of Different Dwelling Types	Research of Elderly	Age Stratification of the Elderly	Neutral Temperature/ Accepted Temperature Range among Different Ages
SC	[43]	Winter	√	×	×	√
	[44]	All	×	×	×	×
	[24]	Winter	√	√	×	×
CZ	[45]	Winter	√	×	×	×
	[39]	Winter	√	√	×	×
	[41]	Winter	√	√	×	×
	[17]	Winter	×	×	×	×
	[46]	Winter	×	×	×	×
	[47]	Winter	×	√	×	×
HSWW	[48]	Summer	×	×	×	×
	[49]	Summer	√	×	×	×
HSCW	[50]	Winter	√	×	×	×
	[51]	Winter	×	×	×	×
This study		Winter	√	√	√	√

), the following research gaps have been identified:

(1)

Lack of comparative studies on thermal comfort differences among elderly people of different age groups in rural areas: Particularly in cold regions with poor indoor thermal environments during the winter, there has been insufficient research on the thermal needs of elderly people across different age groups. Therefore, it is necessary to gain a deeper understanding of the thermal requirements of elderly people of different age groups in such regions.

(2)

Overlooking the impact of different living conditions on thermal comfort: Existing research on the thermal comfort of elderly people in specific regions has not adequately considered the diversity of living conditions. Hence, it is essential to conduct comparative studies on the thermal comfort differences among elderly people living in various dwelling types within the same region.

To address the research gaps regarding the thermal environment and thermal comfort of elderly people living in rural areas of cold zones in China, this study surveyed Yaotou village in the Guanzhong region, a typical region in the cold zone of China, taking into account the differences in living conditions and age. This will provide valuable references for improving the residential thermal environment for elderly people in cold rural areas.

1.5. Research Objectives

The primary objective of this study is to determine the thermal comfort range for elderly people of different age groups in various types of dwellings in the cold climate of the Guanzhong region and to identify the adaptive behaviors they adopt to achieve thermal comfort. Specifically, this study will:

(1)

Utilize a combination of field measurements and questionnaire surveys to comprehensively understand the current indoor thermal environment of different types of dwellings and to fully grasp the thermal needs of elderly people across different age groups.

(2)

Develop an appropriate thermal comfort evaluation model to define the neutral and comfort temperature ranges for various types of dwellings and elderly people of different age groups.

(3)

Based on the thermal comfort evaluation model and the measured neutral and comfort temperature ranges, identify the thermal adaptation differences among elderly people in different types of dwellings and across various age groups, and propose targeted strategies to improve residential performance.

The findings of this study will provide valuable references for enhancing the residential comfort of elderly people in rural areas of the Guanzhong region, addressing the issues of low living standards and poor comfort among the local rural elderly population.

2. Research Objects

2.1. Overview of Guanzhong Region

The Guanzhong region is located in the central part of Shaanxi Province, including five cities: Xi’an (the provincial capital of Shaanxi), Xianyang, Baoji, Weinan, and Tongchuan. According to China’s climate zoning map, it belongs to the cold climate zone (Figure 1). The coldest month is January, and the average outdoor temperature in winter is around −0.1 °C. The hottest month is July, and the average outdoor temperature in summer is around 27.4 °C [47,52]. As one of the most historical regions in China, Guanzhong traditional dwellings have a long history of development and distinctive regional characteristics.

2.2. Overview of Yaotou Village

Yaotou village, located about 155 km northwest of Xi’an, is one of the most culturally distinctive villages in the Guanzhong region (Figure 1). There are 280 households in Yaotou village, and the majority of the villagers are engaged in farming and tofu production. Through in-depth field investigations of villages, existing dwellings can be classified into two types: traditional dwellings and self-built dwellings, based on construction time, building materials, and architectural spatial forms. The first type consists of Guanzhong traditional dwellings, also known as “narrow courtyard dwellings”, which were primarily constructed before 1980 using raw soil as the main building material. These dwellings are normally 8 m to 10 m wide and 20 m to 30 m long from north to south [53], with the main living spaces located in the east and west wing rooms. The second type comprises self-built dwellings made primarily of red bricks, which began to emerge in the early 1990s during the “new rural construction project”, These dwellings retain the narrow and long form of traditional Guanzhong dwellings but enclose the courtyard within the building.

Unlike urban areas, Guanzhong rural areas do not have a unified heating system or a scheduled heating period. Therefore, in winter, residents independently develop heating solutions based on their needs and economic conditions. Normally, heating methods can be categorized into using traditional kang or coal stoves as well as not using any heating measures. This situation is consistent with the findings of Yang Liu et al. [54]. The traditional “Kang” (Figure 2a), is widely used in cold regions of China. It utilizes residual heat from cooking to fulfill the thermal load requirements of the indoor environment, wholly or partially. The coal stove has become a popular alternative (Figure 2b) due to lifestyle changes and the prolonged heating duration with associated high coal consumption [55]. Coal stoves meet both cooking needs and help save on energy costs. Based on the above survey results, this study selected six dwellings as the main research objects, including three traditional Guanzhong dwellings (T1, T2, T3) and three self-built dwellings (S1, S2, S3), each with different heating methods. A comparative analysis of the current indoor thermal environments of these dwellings was conducted.

Table 3. Detailed information on the test objects.

Basic Information	T1	T2	T3	S1	S2	S3
Year of built	1960	1980	1980	1990	2004	1989
Permanent population	2	2	2	2	2	2
Main bedroom orientation	East	East	West	South	South	South
Roof	Traditional timber-framed brick roof			200 mm cast-in-place concrete slab + red tile + sloped roof
External wall	370 mm rammed earth bricks wall walls			370 mm solid red clay bricks
Inner wall	240 mm thick adobe walls			240 mm/120 mm solid red clay bricks
Floor	compacted raw earth + overlaid with blue bricks			Compacted raw earth + concrete + ceramic tiles
Door	Traditional double-opening wooden door			Standard wooden door
Windows	Wooden window frames + single-layer glass			Single-layer aluminum alloy frames with white glass
Heating methods	No heating facility	Coal stove	Kang	No heating facility	Coal stove	Kang

provides detailed information on each dwelling’s construction time, building area, structural type, and other relevant details.

3. Research Methods

Assessing the thermal comfort of the elderly in rural dwellings necessitates a comprehensive approach that considers both objective measurements and subjective perceptions. This study employed a mixed-methods research design, integrating on-site environmental measurements with questionnaire surveys to capture a holistic view of thermal comfort [56].

3.1. Field Measurement

The field measurements were conducted across a representative sample of six dwellings in Yaotou village, selected for their contrasting architectural features and heating systems. To ensure the scientific validity and objectivity of the measurement data, this study followed the testing requirements for indoor thermal environment parameters outlined in the Chinese standards “Evaluation Standard for Indoor Thermal Environment of Civil Buildings” (GB/T50785-2012) [57] and “Code for Thermal Design of Civil Building” (GB50176-2016) [58]. These standards were combined with the specific conditions of traditional dwellings in Yaotou Village to develop a testing scheme for indoor and outdoor thermal environment parameters. The measurements took place during the coldest month of the winter season, from 13 to 17 January 2018. Each dwelling was monitored for a continuous duration of 48 h, with data being recorded at half-hourly intervals to capture diurnal variations in environmental parameters. A statistical analysis of the environmental parameters and research data was then conducted. This methodology was widely employed through on-site investigations of adaptive thermal comfort [59]. The instruments used in the measurements are provided in

Table 4. Measurement instruments.

Instruments	Test Content	Instrument Range	Accuracy	Manufacturer	City/Country
Testo-175	Air temperature Relative humidity	−20–55 °C 0–100%RH	±0.4 °C ±2%RH	Testo SE & Co. KGaA	Lenzkirch/ Germany
JTR04	Globe temperature	5–120 °C	±0.5 °C	Juchuang Group Co., Ltd	Qingdao/China
Kanomax	Air velocity	0.01~20.0 m/s	±0.01 m/s	Kanomax USA, Inc.	Andover/USA
JTR-05	Solar radiation thermometer	−20~85 °C	±0.5 °C	Maikeyi (Beijing) Technology co, Ltd	Beijing/China

. All instruments were calibrated to comply with ISO 7730 standards, ensuring the accuracy and reliability of the data [60]. Indoor measurement points were placed in the center of the main bedroom/living room, the area most frequently used by the elderly, without interfering with the residents’ daily activities. According to specifications, instruments have been positioned at a height of approximately 1.1 m above the ground to prevent direct sunlight through windows and to be distant from indoor heat sources [61]. For outdoor temperature and humidity measurements, the instruments were placed under the shade or shadow at a practical height of 1.5 m from the ground. The measurements were taken simultaneously as the occupants answered the questionnaire surveys, and all were conducted in the main bedroom. Actual on-site photographs are provided in Figure 3. The floor plan of the test subjects and the detailed layout of the measurement points are shown in Figure 4.

3.2. Questionnaire Survey

During the winter survey period, subjective thermal comfort questionnaires were administered to residents of the two types of dwellings in Yaotou Village. Given that the objective of this study is to characterize the thermal needs of elderly people across different age groups, participants were required to be between 60 and 89 years old and in good health to ensure the representativeness of the results.

According to village committee records, Yaotou Village has around 200 residents aged over 60, with roughly 40% in the 60–69 age group, 35% in the 70–79 age group, and 25% in the 80–89 age group. Through field investigation, it was observed that dwellings in Yaotou village shared similarities in layout room functionality, and elderly residents also tended to share similar daily behaviors, habits, and even thermal preferences. Therefore, in further investigation, based on the Frailty Scale developed by Rockwood et al. [62] (

Table 5. Rockwood clinical frailty scale.

Scale	Description
Very fit (1)	People who are robust, active, energetic, and motivated.
Well (2)	People who have no active disease symptoms but are less fit than category 1.
Well with treated diseases (3)	People whose medical problems are well controlled, but are not regularly active beyond routine walking.
Apparently vulnerable (4)	While not dependent on others for daily help, often symptoms limit activities.
Mildly frail (5)	People often have more evident slowing and need help in high-order IADLs.
Moderately frail (6)	People need help with all outside activities and with keeping house.
Severely frail (7)	Completely dependent on personal care, from whatever cause.

), healthy elderly (scored between 1 and 3) were selected. This scale has been validated for assessing the relative health and frailty of elderly patients [63,64]. From this group, elderly individuals who had lived in the area for more than 10 years and had adapted to the local climate were further selected. Ultimately, 80 elderly individuals were chosen for this study, and their age segmentation roughly matched the existing age distribution in the village (

Table 6. Age statistics of the selected elderly residents.

Dwelling Type	Total	60–69	70–79	80–89
Traditional dwelling	40	45%	40%	15%
Self-built dwelling	40	60%	27.5%	12.5%

). Although the sample size is relatively small, many previous studies on thermal comfort have already used similar or even smaller sample sizes and achieved commendable results [65,66,67,68,69]. All the elderly participants surveyed have lived in the area for over ten years, have adapted to the local climate, and are considered healthy according to Rockwood’s Frailty Scale. The questionnaire survey did not involve their privacy or harm their physical or mental health. In this study, all respondents are well aware of the purpose of the interview results and have given consent for the subsequent use of the interview outcomes.

The questionnaire was designed based on ASHRAE’s seven-point thermal sensory scale [61], as shown in

Table 7. ASHRAE’s seven-point thermal sensory scale.

Cold	Cool	Slightly Cool	Neutral	Slightly Warm	Warm	Hot
−3	−2	−1	0	+1	+2	+3

, and was divided into three sections to gather detailed information on dwelling characteristics, resident demographics, and thermal comfort perceptions (Appendix A). The questionnaires were administered by the author and answered by the elderly respondents, with the author recording the responses. Each questionnaire took at least 20 min to complete, and the contents and scores were initially recorded in Chinese. Subsequently, they have been translated into English to ensure accuracy and consistency.

3.3. Evaluation Index

This research used the Bin method (where the operative temperature was divided into intervals of 0.5 °C) and employed regression analysis to model the relationship between operative temperature and measured thermal comfort sensation voting (MTS), allowing us to estimate the neutral temperature and the acceptable temperature range for different dwelling types and age groups [70,71,72]. Using Origin 2018 software, a univariate linear regression analysis was conducted on the variables to obtain the fitted lines of MTS and effective temperature for the two types of dwellings in winter. This method has been proven feasible in previous studies on the thermal comfort evaluation of traditional dwellings. The measured thermal comfort model was developed after completing the data collection. Further, the indoor thermal comfort of two different types of dwellings and the thermal comfort of the elderly in different age groups were analyzed and compared. Unlike buildings in cities, rural dwellings are typically single-story independent buildings. Two primary factors affect the thermal comfort of rural residents: air temperature and mean radiant temperature. The average radiant temperature (t_r) is obtained by calculating the air temperature (t_a), globe temperature (t_g), and air velocity (v) [60]. Based on ASHRAE 55 standards, when the average air velocity is less than 0.2 m/s, it can be calculated by Equation (1).

$$t_r^{ }={\left[{\left(t_g^{ }+273\right)}^4+2.5 \times {10}^8{v}^{0.6}\left(t_g^{ }-t_a^{ }\right)\right]}^{0.25}-273$$

(1)

Also, the operative temperature (t_op) was chosen as the evaluation index to examine the relationship between air temperature (t_a), average radiation temperature (t_r), and human thermal sensation. It can be calculated by Equation (2) [60].

$$t_{op}^{ }=\left(t_a^{ }+t_r^{ }\right)/2$$

(2)

4. Results and Discussion

4.1. Indoor Thermal Environment Data Analysis

The indoor environmental parameters can significantly affect human comfort. Figure 5 illustrates the variations in indoor parameters of traditional dwellings under three heating methods. The collected data revealed significant variations in the indoor thermal environment across different dwelling types and heating methods. During the winter months, the average outdoor temperature in Yaotou village fluctuated between −3.3 °C and 0.1 °C. Traditional dwellings without heating (T-1) exhibited indoor air temperatures ranging from −1.2 °C to 3.4 °C, with an average of 0 °C. This indicates a strong correlation between outdoor temperatures and indoor conditions due to the lack of heating and insufficient insulation. Dwellings with coal stove heating (T-2) showed an indoor air temperature range of 3.1 °C to 8.2 °C, averaging 5.3 °C. Notably, these dwellings experienced a pronounced temperature drop during early mornings, with a subsequent increase during cooking times, reflecting that the residents only strengthened the fire intensity during cooking time and utilized the residual heat of the coal stove for heating during other times. Traditional kang heating dwellings (T-3) maintained the highest and most stable indoor air temperatures, ranging from 6.9 °C to 9.1 °C, with an average of 7.4 °C. However, this heating method was also the costliest in terms of heating expenses.

Self-built dwellings, even without heating (S-1), displayed higher indoor air temperatures than traditional dwellings, averaging 2.5 °C. The indoor air temperature of S-1 was higher than that of T-1 due to the relatively newer construction and better insulation. However, the fact that the buffer space between rooms and outdoor space was not considered during the construction and the lack of airtightness of maintenance structures, such as windows and doors, has resulted in the indoor air temperature being significantly influenced by the outdoor temperature. For the coal stove heating dwelling (S-2), the indoor air temperature ranged from 5.9 °C to 9.8 °C, with an average air temperature of 8.1 °C. In the case of traditional kang heating (S-3), the indoor air temperature ranged from 6.8 °C to 11.7 °C, with an average air temperature of 9.5 °C.

The average indoor air temperature of traditional dwellings was 4.2 °C, and the average indoor air temperature of self-built dwellings was 8.2 °C. Regardless of the heating methods, the indoor air temperature of self-built dwellings was higher than that of traditional dwellings. This is due to the long construction period of traditional dwellings, where the raw soil walls have deteriorated significantly over time and lack insulation layers, resulting in poor overall thermal performance. Additionally, enclosure structures such as doors and windows are mostly made of wood, which has poor sealing properties, leading to substantial indoor heat loss and an inability to maintain a comfortable indoor temperature. However, these dwellings still fell short of the Chinese standards for civil buildings, which mandate maintaining indoor temperatures between 18 °C and 24 °C during the winter [57].

The humidity data for two types of dwellings during the winter are illustrated in Figure 6. Throughout the surveyed period, the average humidity in traditional dwellings was 50.6%, while in self-built dwellings, it was 42.4%. Among the self-built dwellings, S-1 exhibited the lowest humidity at an average of 31%, and among the traditional dwellings, T-2 had the lowest humidity at an average of 36.3%. Simultaneously, the average humidity in traditional dwellings was higher than that in self-built dwellings. This difference could be attributed to the fact that traditional dwelling walls were typically constructed with raw earth, which possesses a certain hygroscopicity. Additionally, the lack of a moisture-proof layer in the envelope structure was one of the reasons. According to GB/T 50785-2012 [57], the acceptable range of relative humidity in indoor environments during the winter was between 30% and 60%, S-1 was lower than the regulation, and T-3 was higher than the regulation. This suggested that reducing indoor humidity and increasing indoor air temperature can best optimize the indoor thermal environment of “Kang” heating traditional dwellings. Conversely, for self-built dwellings without heating, elevating indoor air temperature and humidity levels at the same time is important.

Compared with the measured data with the standard enthalpy-humidity diagram in the ASHRAE 55 standard, as shown in Figure 7, it can be seen that both dwellings’ thermal comfort zones deviate significantly from the standard comfort zones. Thus, it was necessary to advance research on enhancing thermal comfort in both types of dwellings.

4.2. Clothing Thermal Resistance and Adaptive Behavior

Before the survey, most participants were engaged in light activities with relatively low metabolic rates, such as standing, sitting, chatting, or watching television. Based on the metabolic rates of common activities specified in the Chinese “Evaluation Standard for Indoor Thermal Environment of Civil Buildings” (GB/T50785-2012) [57], the metabolic rate of the elderly was calculated to be 1.2 Met. Due to lifestyle habits and a tendency to be more susceptible to colds, elderly respondents wore relatively thicker clothing. According to the standards provided by ASHRAE 55 [61], the elderly’s clothing is recorded in detail, and the distribution of clothing thermal resistance is shown in Figure 8. The range of clothing thermal resistance was distributed between 1.3 clo and 2.5 clo, with a concentration between 1.5 clo and 2.1 clo and an average value of 1.83 clo. The clothing thermal resistance among the elderly was notably higher in traditional dwellings (2.06 clo) compared to self-built dwellings (1.75 clo), with the highest resistance observed in the 80–89 age group at 2.3 clo. This suggests that the elderly in traditional dwellings have adapted to the colder indoor environment by wearing thicker clothing. The clothing thermal resistance was also found to increase with age; this finding is aligned with Yu et al. [73]. Compared with the elderly in other regions [24,43], it can be seen that the clothing thermal resistance of the elderly in the Guanzhong region was higher than that of other areas.

Studies examining the relationship between psychological adaptation and thermal comfort have indicated that thermal comfort has a synergistic effect on subjective human evaluation [74,75]. When the indoor thermal environment cannot meet thermal comfort requirements, rural residents tend to make behavioral adjustments to adapt to their surroundings. The most common adaptive behavior for the elderly living in traditional dwellings was sunbathing (33%), followed by changing clothes (21%). The most common adaptive behavior for the elderly in self-built dwellings was added fuel (35%), higher than that in traditional dwellings (16%). Through the analysis of the relationship between clothing thermal resistance and indoor operative temperature in two dwellings, the regression curve of clothing thermal resistance and operative temperature is shown in Figure 9. A strong correlation was found between clothing thermal resistance and operative temperature, indicating that residents adjust their clothing to achieve thermal comfort in response to indoor temperature variations. At the same time, there is a strong correlation between clothing thermal resistance and operative temperature in self-built dwellings (R² = 0.9384), indicating that residents adjust their clothing in response to temperature changes to achieve thermal comfort. However, in traditional dwellings, the correlation is weaker (R² = 0.6228), with a higher degree of data dispersion. This suggests that elderly residents in traditional dwellings, having lived in lower indoor temperatures for an extended period, rely on high-thermal-resistance clothing to maintain thermal comfort regardless of temperature changes. This is consistent with the adaptive behavior survey results, showing that adding clothes is a primary method for coping with winter temperatures in traditional dwellings.

4.3. Thermal Sensation Vote

A commonly employed method for assessing respondents’ thermal comfort levels is the Thermal Sensation Vote (TSV). Thermal sensation is an indicator of feeling warm or cold in a thermal environment and is assessed using the ASHRAE 7-point scale (from −3 to +3), where −3 and +3 represent the extremes of cold and hot, respectively. As illustrated in Figure 10, the most frequently reported thermal sensation in traditional dwellings was “cool,” while in self-built dwellings, it was “slightly cool”. The calculation of the Thermal Acceptance Range, defined within the range of −1 to 1, revealed an acceptable zone comprising 45% of traditional dwellings and 68% of self-built dwellings. Within the −3 to −1 voting range, traditional dwellings exhibited the highest voting proportion (80%). The average thermal sensation score was −0.83 for self-built dwellings, which is higher than the −1.48 observed for traditional dwellings, suggesting greater satisfaction among residents of self-built dwellings.

Noteworthy was the fact that the voting rate for the elderly aged 60–69 fell within the acceptable range of 62%. This proportion diminished with increasing age, possibly indicating an elevated sensitivity to lower temperatures among the elderly, who might want a warmer indoor environment. In the −3 to −1 voting range, the elderly aged 60–69 exhibited the lowest voting rate at 62%, potentially attributed to their generally stronger self-regulation abilities compared to older age groups, and also had a relatively higher acceptance of lower temperature.

4.4. Thermal Comfort Evaluation Model

4.4.1. Neutral Temperature and Accept Temperature Range of Two Types of Dwellings

Thermal neutrality is defined as a state in which occupants experience a sensation that is neither too cold nor too hot. In other words, it refers to the operational temperature at which thermal sensation ratings converge to zero, commonly referred to as the neutral temperature or comfort temperature. The collected data were subjected to rigorous statistical analysis to determine the relationship between environmental parameters and perceived thermal comfort. According to the steady-state evaluation model invented by Fanger [76], the measured thermal comfort evaluation model was established based on field measurement and questionary survey data. Origin 2018 software was used to carry out unary linear regression analysis on the variables to obtain the fitting straight lines between the MTS and operating temperature of the two types of dwellings in winter, as shown in Figure 11. The linear equation obtained by regressing traditional dwellings is shown in Equation (3). By assigning the MTS value to 0, respectively, the measured thermal neutral temperature can be calculated as 8.46 °C. By assigning the MTS value as −0.5 to 0.5, respectively, the measured 90% acceptable indoor thermal comfort temperature range based on the behavioral habits, physiological, and psychological characteristics of the residents can be calculated as [7.58–9.33 °C].

$$MTS=0.5691t_{op}-4.8125(R^2=0.9453)$$

(3)

The linear equation obtained by regression of self-built dwellings is shown in Equation (4), and the measured neutral temperature was calculated as 10.53 °C, and 90% acceptable temperature range was calculated as [9.88–11.18 °C].

$$MTS=0.769t_{op}-8.0954(R^2=0.9571)$$

(4)

There was a significant difference between the measured neutral temperature of traditional and self-built dwellings. The measured neutral temperature of self-built dwellings was higher than that of traditional dwellings. The slope of the thermal comfort evaluation model can also reflect the sensitivity of residents’ thermal sensation to changes in indoor operative temperatures [43]. The thermal sensitivity of the elderly in self-built dwellings was higher than that in traditional dwellings. According to GB/T 50785-2012 [57], the measured acceptable temperature by 90% of the population was obtained. This indicates that the elderly in this temperature range will experience comfort. It can be seen that the elderly in traditional dwellings demonstrated greater adaptability to low temperatures and indoor air temperature variations. Additionally, 30% of the elderly who live in traditional dwellings chose “no change” in temperature preference, with an average neutral temperature of 8.8 °C. In contrast, 40% of the elderly who live in self-built dwellings chose “no change” with an average neutral temperature of 10.55 °C. The thermal neutral temperatures were closely aligned with the temperatures supported by the “no change” response in the thermal acceptability votes. Previous studies [77] have also validated this result.

Comparing two types of dwellings’ indoor air temperatures with the thermal neutral temperature showed that both air temperatures were below the thermal neutral temperature, indicating that the current indoor thermal environment could not meet the thermal needs of the elderly residents. This also suggested that when the thermal sensation vote was 0, it did not necessarily imply residents’ satisfaction with the current thermal environment. This observation was in line with the concept of the “semantic artifact” proposed by de Dear et al. [78].

4.4.2. Thermal Expectation Temperature of Two Types of Dwellings

The thermal expectation temperature refers to the temperature that residents statistically wish to achieve. The respondents’ thermal temperature preference voting result showed that 30% of the elderly respondents chose “no change”, 65% of the respondents chose “warmer”, and 5% of respondents chose “cooler” in traditional dwellings. And 40% of respondents chose “no change”, 57.5% of respondents chose “warmer”, and 2.5% of respondents chose “cooler” in self-built dwellings. Therefore, probabilistic statistical methods were used to calculate the percentage of respondents who preferred warmer or cooler in each temperature interval, using the operative temperature as the independent variable. Then all the data were fitted separately and displayed in Figure 12. The temperature at the intersection of these two fitted curves represents the expected temperature. The fitted equations of traditional dwellings are shown in Equations (5) and (6).

$$y_{warmer}=0.711x^3-15.007x^2+95.005x-152.54(R^2=0.8448)$$

(5)

$$y_{cooler}=0.0932x^3-1.5245x^2+8.1277x-14.153(R^2=0.5043)$$

(6)

The fitted equations of self-built dwellings as shown in Equations (7) and (8).

$$y_{warmer}=-8.9394x^3+239.93x^2-2116.3x+6154.3(R^2=0.599)$$

(7)

$$y_{cooler}=1.25x^2-22.231x+97.83(R^2=0.6667)$$

(8)

The calculations determined that the expected winter temperature of traditional dwellings was 9.45 °C, and it was 11.08 °C for self-built dwellings, both exceeding the thermal neutral temperature. The expected temperature of traditional dwellings exceeded the higher limit of the 90% acceptable temperature interval, and that of self-built dwellings was close to the higher limit of the 90% acceptable temperature interval.

4.4.3. Neutral Temperature and Accept Temperature Range of Different Age Groups

In addition to the thermal environmental factors affecting human thermal sensation, individual qualities such as age also affect how comfortable individuals feel in their environment. This section explored the relationship between age groups and operative temperature to better understand the differences in comfort requirements of the elderly among different age groups. The relationships between different age groups and operative temperature are shown in Figure 13. The linear equation obtained by regression analysis of the TSV and operative temperature of people in the 60–69 age group is shown in Equation (9), and the predicted neutral temperature was 10.07 °C, 90% acceptable temperature range was [8.89–11.25 °C].

$$TSV=0.4235t_{op}-4.2663(R^2=\begin{array}{c}0.5139\end{array})$$

(9)

The linear equation obtained by regression analysis of the TSV and operative temperature of people in the 70–79 age group is shown in Equation (10), and the predicted neutral temperature was 10.60 °C, 90% acceptable temperature range was [9.43–11.77 °C].

$$\begin{array}{c}TSV=0.4271t_{op}-4.5261\end{array}(R^2=0.7357)$$

(10)

The linear equation obtained by regression analysis of the TSV and operative temperature of people in the 80–89 age group as shown in Equation (11), and the predicted neutral temperature was 11.52 °C, 90% acceptable temperature range was [10.35–12.68 °C].

$$\begin{array}{c}TSV=0.4311t_{op}-4.9643\end{array}(R^2=\begin{array}{c}0.9195\end{array})$$

(11)

In summary, the highest neutral temperature was found in the 80–89 age group. The neutral temperatures of the elderly decreased with age, with a discrepancy of 1.45 °C between the 80–89 age group and the 60–69 age group. In contrast, the 80–89 age group had the highest sensitivity to indoor temperature changes due to the deterioration of their body functions and had correspondingly higher minimum acceptable temperatures and clothing thermal resistances. In addition, the average thermal preference also reflects this trend, with the average thermal preference values of −0.93, −1.25, and −2 for the age groups of 60–69, 70–79, and 80–89, respectively. The previous analysis also indicated that the elderly in the Guanzhong rural area have been living in relatively poor indoor environments for a long period of time and already have a strong adaptation to them. However, as the age increased and the living standards improved, the demands of elderly indoor thermal comfort needs also increased. Current indoor environments cannot satisfy their needs, and warmer indoor environments are needed for them to obtain comfort levels, especially for the elderly aged 80 and above.

4.4.4. Thermal Comfort Evaluation Models and High Accuracy Fitting Equations

To accurately evaluate the thermal comfort of the elderly in different age groups, various types of models were comparatively analyzed. The five highest-accuracy fitting equations for each age group have been found and developed. These equations are designed to accurately assess the thermal comfort perception of the elderly across different age groups. The five highest-accuracy fitting equations for 60–69 were developed as shown in Equations (12)–(16). All the corresponding coefficients of the model are shown in Appendix B.

$$TSV=a+b{t}_{op}+c/t_{op}+d{t}_{op}{ }^2+e/t_{op}{ }^2+f{t}_{op}{ }^3+g/t_{op}{ }^3$$

(12)

$$TSV=a+b{t}_{op}+c{t}_{op}{ }^{1.5}+d{t}_{op}{ }^{2.5}+e\ln t_{op}2$$

(13)

$$TSV=a+b{t}_{op}{ }^{0.5}+c{t}_{op}+d{t}_{op}{ }^{1.5}+e{t}_{op}{ }^2+f{t}_{op}{ }^{2.5}$$

(14)

$$TSV=a+b{t}_{op}+c{t}_{op}{ }^{2.5}+d/t_{op}+e\ln t_{op}/t_{op}{ }^2$$

(15)

$$TSV=a+b{t}_{op}+c{t}_{op}{ }^3+d/t_{op}+e\ln t_{op}/t_{op}{ }^2$$

(16)

The five highest accuracy fitting equations for 70–79 were developed as shown in Equations (17)–(21):

$$TSV=a+b{t}_{op}+c{t}_{op}{ }^{2.5}+d{t}_{op}{ }^3+e/t_{op}{ }^{0.5}$$

(17)

$$TSV=a+b{t}_{op}+c{t}_{op}{ }^{2.5}+d/t_{op}{ }^{0.5}+e\ln t_{op}/t_{op}{ }^2$$

(18)

$$TSV=a+b{t}_{op}\ln t_{op}+c{t}_{op}{ }^{1.5}+d{t}_{op}{ }^2$$

(19)

$$TSV=a+b{t}_{op}+c{t}_{op}{ }^2+d{t}_{op}{ }^{2.5}+e/t_{op}{ }^{0.5}$$

(20)

$$TSV=a+b{t}_{op}+c{t}_{op}/\ln t_{op}+d/t_{op}{ }^{0.5}+e/t_{op}$$

(21)

The five highest accuracy fitting equations for 80–89 were developed as shown in Equations (22)–(26):

$$TSV=a+b{t}_{op}+c{e}^{t_{op}}+d/t_{op}{ }^{0.5}+e\ln t_{op}/t_{op}$$

(22)

$$TSV=a+b{t}_{op}+c{e}^{t_{op}}+d{t}_{op}{ }^{0.5}+e{e}^{-t_{op}}$$

(23)

$$TSV=a+b{t}_{op}+c{e}^{t_{op}}+d{t}_{op}{ }^{0.5}\ln t_{op}+e{e}^{-t_{op}}$$

(24)

$$TSV=a+b{t}_{op}+c{e}^{t_{op}}+d{t}_{op}/\ln t_{op}+e/t_{op}$$

(25)

$$TSV=a+b{t}_{op}+c{t}_{op}\ln t_{op}+d{e}^{t_{op}}+e{t}_{op}/\ln t_{op}$$

(26)

4.4.5. Strategies and Recommendations for Improving the Indoor Thermal Environment

Through the above analysis, we can further observe that residents of both types of dwellings have a certain degree of adaptability and tolerance to low winter temperatures. However, compared to the elderly in self-built dwellings, those living in traditional dwellings exhibit higher tolerance, a broader acceptable range, and stronger adaptive capacity to winter conditions. The primary reasons include the longer construction period of traditional dwellings, the deterioration of raw soil walls over time, poor maintenance structures, and economic factors. As a result, residents who have lived in such environments for a long time have developed strong behavioral, physiological, and psychological adaptations to low-temperature conditions. However, with increasing age and improving living standards, the demand for indoor thermal comfort among the elderly also rises. The existing indoor environment can no longer meet their needs, and a warmer indoor environment is required to achieve comfort, especially for elderly individuals over 80 years old, who are most sensitive to temperature changes. Based on the findings, several strategies and recommendations are proposed to enhance the thermal comfort of the elderly in the Guanzhong region, adhering to the principles of protecting local culture, optimizing comfort for the elderly, and ensuring economic viability. Implementing the findings of this study will help improve the quality of life for the elderly in their dwellings, thereby enhancing their well-being and productivity.

(1) For the elderly in different age groups, current research shows that the expected temperature among elderly residents in traditional dwellings is 9.45 °C, while in newly built dwellings, it is 11.08 °C. At the same time, the demand for indoor temperatures among elderly people aged 60–80 shows an increasing trend. The results of adaptive behavior studies also indicated that elderly individuals take various measures to improve their thermal comfort, such as adjusting clothing, sunbathing, adding fuel, and ventilating by opening windows. Therefore, indoor spaces should be designed to provide an adjustable thermal environment, such as with adjustable curtains, fans, and heating equipment, to cater to the personalized needs of elderly individuals across different age groups [79]. Additionally, the primary activity areas for the elderly should maximize the use of natural lighting and ventilation to accommodate their preference for sunlight and sunbathing habits [80]. The functional setup of the main space should be as flexible and adjustable as possible to meet the varying thermal comfort needs of the elderly at different stages of life.

(2) For traditional dwellings, improving the thermal insulation performance of the building envelope during the winter is a key focus of renovation. Based on the measurements and analysis in Section 4.1, traditional dwellings have been constructed for a long time, and the earthen walls have developed severe cracks and damage over time. Research by the International Centre for Earthen Architecture (CRATerre-ENSAG) has shown that a low sand content is one of the main reasons for the susceptibility of traditional earthen walls to cracking [81]. Therefore, it is recommended to modify the traditional earthen walls by adding materials such as setaria viridis [82], fine sand, gravel [83], or 5–20% stabilizers [84] to enhance the compressive strength and durability of the earthen walls. Additionally, adding insulation layers can improve the thermal performance of the walls, preserving the cultural texture of the original exterior walls while taking full advantage of the hygroscopic properties of rammed earth to maintain indoor humidity, thereby enhancing the thermal comfort of the elderly. Furthermore, the envelope structures of traditional dwellings, such as doors and windows, are often made of wood with single-pane glass, which provides poor sealing and leads to significant indoor heat loss, making it difficult to maintain a comfortable indoor temperature. Measures such as changing the door and window materials, increasing the number of glass layers, and using glass with high light transmittance, low radiation, and strong thermal resistance can reduce the thermal exchange between cold and warm air, thereby ensuring the health and comfort of the residents.

(3) For self-built dwellings, the focus should be on improving low indoor humidity in winter and the maintenance structure of doors and windows. Humidifying devices can be used timely to increase the indoor relative humidity, which is suitable for the elderly. Additionally, adding a sunroom as a buffer space can reduce the indoor heat loss in the main living areas, thereby reducing the use of heating fuel and lowering the building’s energy consumption, cost, and carbon emissions.

This study revealed the winter thermal environment characteristics and comfort levels of elderly residents in two types of dwellings in the Guanzhong region. It proposed a thermal comfort evaluation model tailored to elderly individuals of different age groups in this region, explored the desired comfort temperature for the elderly, and provided relevant improvement recommendations and strategies. The renovation measures adopted in this study are well-established; however, future research should further explore the application of new materials and technologies.

4.5. Discussion

4.5.1. Comparison of the Current Study with Other Studies in Different Regions

By comparing different climate zones, the average clothing thermal resistance in this study was found to be 1.83 clo, exceeding the observed average of 1.29 clo in severely cold rural areas [43] and 1.60 clo for the elderly in hot summer and cold winter rural areas [45]. On the contrary, the clothing thermal resistance seemed to be lower compared with a previous study in the same Guanzhong region, which was found to be 1.95 clo [54]. It can be seen that clothing thermal resistance has exhibited a decreasing trend in the Guanzhong region from 2011 to 2018, and the requirement for an indoor thermal environment might increase. The adoption of higher clothing thermal resistance might indicate a certain adaptability to cold indoor environments. And the courtyard layout of rural Guanzhong dwellings dictated that residents needed to enter and exit frequently; higher clothing thermal resistances were conducive to ease of movement. Moreover, it may reflect an economic consideration by residents in the Guanzhong region, reducing the demand for energy sources like heating by choosing thicker clothes.

The thermal neutral temperature and acceptable temperature range for rural elderly residents across different climate zones were compared (

Table 8. Summary of neutral temperature and acceptable temperature range across different climate zones.

Article	Climate Zone	Age	Dwelling Type	Neutral Temperature/°C	Acceptable Temperature Range/°C
[45]	CZ	-	Traditional and new	18.1; 19.8	15.8–20.3; 16.8–22.8
[54]	CZ	-	Traditional	11.7	>8.0
[85]	CZ	-	Traditional	11.9	-
[86]	CZ	-	-	13.7	-
[37]	HSCW	65+	Traditional and new	-	16.7–27.1
[87]	HSCW	-	Urban and rural	14; 11.5	-
[43]	SC	18–77	3 latitudes rural	18.6; 17.8; 17.3	14.6–19.1; 14.4–18.6; 13.9–18.2
This study	CZ	60–89	Traditional and self-built	8.46; 10.53	7.58–9.33 9.88–11.18

). The acceptable thermal temperature ranges of the elderly in this study were lower than those of severe cold regions (14.16–18.9 °C) [43] and hot summer cold winter regions (16.7–27.1 °C) in China. The Guanzhong rural area exhibited a lower thermal neutral temperature, with a correspondingly narrower acceptable temperature range. This suggested that the elderly in this region, accustomed to prolonged exposure to colder environments, exhibited a certain degree of adaptability to cooler thermal conditions. They can tolerate a lower minimum temperature limit, and their expectations for the upper temperature limit were also comparatively lower. Delving into the differences in thermal neutral temperature and acceptable temperature ranges between studies within the same Guanzhong region, the thermal neutral temperature in the previous study was 11.7 °C, with a minimum acceptable temperature of 8 °C. There is a small difference between the findings from the previous study and the current study due to the age difference among the research participants. Comparisons revealed that despite the differences in the ages of the participants, their neutral and acceptable temperatures are lower than those in other regions. This further indicated that the indoor thermal environment in this area during the winter is poor, and therefore, it should receive more attention.

4.5.2. Limitations and Future Challenges

Although this research analyzed the current state of thermal comfort among the elderly in different types of dwellings in cold climate zones and across various age stratifications, there are still some limitations. Firstly, the relatively small sample size imposed certain limitations. While the proportions of respondents in each age group were similar to the population distribution in the surveyed village, the relatively small sample size might not fully capture the variability present in a more extensive population, thus presenting certain constraints. In future studies, prioritizing the expansion of the sample size to improve result representativeness and fortify the validity of the conclusions is essential. Secondly, when discussing the thermal needs of the elderly in different age stratifications, this study did not consider the elderly in specific health conditions or above age 90. Incorporating respondents with significant illnesses, physical disabilities, and those aged over 90 will be involved in future research plans to discern the impact of health conditions on age-related thermal adaptation. Thirdly, the selection of dwellings in this study was primarily based on construction materials and heating methods, overlooking the impact of factors such as orientation and human activities. Future research will address this by conducting more extensive surveys and making more detailed comparisons across different types of dwellings. Fourthly, this study primarily focused on winter, while summer and transitional seasons are crucial for investigating the thermal comfort of the elderly. Future work will encompass additional research on climate samples to thoroughly investigate indoor thermal environments and the preferences of the elderly throughout the entire year.

The research findings can be utilized to provide design support for new rural construction and the renovation of old residential dwellings. The paper underscores the importance of focusing on the thermal comfort status of the elderly, particularly the impact of their physiological and psychological needs on the thermal environment. Although the study’s sample size is small, it pioneers a new area of research concerning the thermal environment for the elderly, especially in rural areas with cold climates. Building on this study’s methodology and findings, future research will extend this analysis to include the summer and transitional seasons. It will also investigate the impact of thermal comfort on the elderly with varying health conditions. These endeavors aim to enhance the applicability of the findings and provide a more comprehensive framework for addressing the thermal comfort challenges faced by the aging population in rural areas.

5. Conclusions

The present study delves into the intricacies of indoor thermal comfort within rural dwellings in China’s cold climate zone, with a spotlight on the Guanzhong region. Through meticulous field measurements and comprehensive questionnaire surveys, this research has shed light on the thermal comfort experienced by the elderly across two predominant types of dwellings and various age brackets. The findings can be summarized as follows:

(1) The self-built dwellings registered a notably higher thermal sensation score of −0.83 compared to the traditional dwellings’ score of −1.48. This indicates that the elderly in traditional dwellings experience greater discomfort than those in self-built dwellings. Within the thermal acceptance range (−1 < TSV < 1), the highest voting rate was among elderly people aged 60–69 (62%), and the acceptance rate decreases with age. This suggests that dissatisfaction with the overall thermal environment increases with age among the elderly.

(2) The average winter clothing thermal resistance for the elderly in the Guanzhong region was measured at 1.83 clo, with traditional dwelling residents exhibiting a higher resistance (2.06 clo) than those in self-built dwellings (1.75 clo). This increase with age emphasizes the necessity for adaptive thermal strategies, particularly in traditional dwellings.

(3) The study determined that the neutral temperature for traditional dwellings was 8.46 °C, with an expected temperature of 9.45 °C and a 90% acceptable range between 7.58 °C and 9.33 °C. For self-built dwellings, the neutral temperature stood at 10.53 °C, with an expected temperature of 11.08 °C and an acceptable range of 9.88–11.18 °C. These findings indicate a remarkable adaptability of residents to the cold climate, with traditional dwelling residents showing a higher tolerance. The obtained comfort temperature range is narrower than in other areas.

(4) The neutral temperature for the 60–69 age group was 10.07 °C, with a 90% acceptable range from 8.89 °C to 11.25 °C. For the 70–79 age group, the neutral temperature was 10.60 °C, with an acceptable range of 9.43–11.77 °C. The oldest age group, 80–89, had a neutral temperature of 11.52 °C and an acceptable range from 10.35 °C to 12.68 °C. These results reveal a correlation between age and preferred thermal neutrality, with older residents favoring warmer environments.

This study’s findings provide actionable insights for policymakers and architects, advocating for the incorporation of thermal comfort considerations in the design and renovation of rural dwellings. The research also paves the way for further studies to explore the thermal comfort of the elderly across different seasons and varying health conditions, ultimately contributing to a more inclusive and comfortable living environment for the aging rural population.