Summer Energy Use and Comfort Analysis in Rural Chinese Dwellings: A Case Study of Low-Income Older Populations in Shandong ^†

Abstract

This paper aims to investigate the indoor environmental conditions and energy use behaviours of older individuals in rural cold climates of China, with a specific focus on cooling practices during the summer months in the Shandong region. This study employs a mixed-method approach, combining quantitative indoor environmental monitoring with qualitative interviews and observations, to explore the relationship between environmental factors, household living conditions, and energy use patterns across five types of elderly households: three generations living together, older people living with grandchildren, older people living with children, older couples living together, and older people living alone. Data collection was conducted over five weeks during the summer of 2023 using HOBO UX100-003 data loggers, while external weather conditions were monitored by the China Meteorological Administration. Face-to-face interviews were conducted to gain deeper insights into daily cooling behaviours and energy use. The results reveal that cooling practices and indoor environmental conditions vary significantly among the different household types. Multigenerational households showed more complex energy use dynamics, with younger family members frequently operating high-energy appliances like air conditioners, while older individuals tended to rely on natural ventilation and electric fans to reduce energy costs. In contrast, older couples and solitary older individuals demonstrated more conservative cooling behaviours, often enduring higher indoor temperatures due to limited financial resources and a desire to minimize energy expenditures. Despite the high energy use intensity in some households, many homes failed to achieve comfortable indoor environments, particularly in dwellings with minimal insulation and older building materials. This study concludes that economic status, household structure, and building characteristics play crucial roles in shaping cooling behaviours and indoor comfort during the summer.

1. Introduction

In China, substantial national ongoing rural-to-urban migration leads to an escalating ageing population concentration in rural areas. In 2021, people over 60 years old comprised 23.8% of the Chinese rural population, compared with 15.8% in cities [1]. This 8.0% gap has almost doubled when compared with the 4.3% recorded in 2015 [2].

The majority of older rural residents in China are characterized by below-average to low levels of per capita income [3]. Houses occupied by older rural people are poorly designed and maintained, with poor internal air quality and high heating energy consumption, leading to major problems with thermal comfort [4,5]. Heavily relying on biomass and other solid fuels, these households have limited access to clean and efficient domestic heating systems [6].

Rural residential buildings consume 23.76% of China’s total energy, with relatively low energy efficiency, particularly in the northern regions of China, known for their extreme seasonal temperature fluctuations between 41.1 °C in summer and plummeting to as low as −53 °C in winter [7]. Yang et al. [8] recognize that northern rural houses are normally built without sufficient insulation. Wang et al. [9] indicate that the thermal environment quality of traditional houses in cold climate zones is inferior. Given the unique demographic structure of rural areas in China, where more than 60% of the older population and children often remain in villages, while the young, working-age population migrates to urban centres for employment, creating a phenomena of “elderly villages”, it is particularly important to understand thermal comfort behaviours and implications for energy use [10].

In China, the caregiving system has long been dominated by the concept of “familialism”, where approximately three-quarters of the rural ageing population rely entirely on family support. Both legal frameworks and societal norms emphasize the responsibility of children to care for their parents. However, with the large-scale migration of rural labourers to urban areas, many older adults are left separated from their children for extended periods, disrupting the traditional family-based care model [11]. The intensification of rural depopulation has led to a situation where older individuals are compelled to live independently or rely on remittances from family members for their livelihood. Combined with the long-term effects of the one-child policy, this has posed significant challenges to the future of family-based care for the ageing population in rural China [12]. These shifts in social structure have not only impacted the financial circumstances of older adults but have also altered their patterns of energy consumption.

Studies on energy usage patterns in rural households reveal that residents’ electricity usage behaviour is influenced by income level, educational background, household size, and the number of electrical appliances owned [13]. When rural household members exceed the age of 60, electricity consumption significantly declines. Even during extreme weather conditions in summer and winter, they tend to rely on natural ventilation and traditional heating methods for comfort [14,15]. Nonetheless, the findings of Cui et al. [16] present a contrasting scenario, revealing that rural residents in China’s hot summer and cold winter climate regions tend to use air conditioning systems for heating without realizing that their behavioural patterns may lead to high energy consumption. The survey by Wu et al. [17] found that up to 79% of rural households in northern China continue to use traditional low-efficiency self-constructed stoves. A total of 17.1% and 58.6% of rural residents use coal and solid biomass as their main cooking fuel, respectively, while areas with lower per capita household incomes use more solid fuels [18].

Studies have shown that decision-making processes within households also significantly impact energy consumption. Research by Lin et al. [19], based on interviews with multigenerational families, highlighted generational differences in consumption patterns. Younger members tend to use high-energy appliances more frequently, while older individuals often reduce their use of such devices to save costs [20]. This finding is further corroborated by my research, demonstrating that generational differences in energy consumption decisions are prevalent across low-income rural household structures. In resource-limited situations, these generational differences can easily lead to internal conflicts over energy use. Such conflicts are often resolved through negotiation and compromise among family members.

The existing literature reveals a significant gap in understanding the energy use behaviour of older individuals in rural China, particularly in relation to the influence of family structures and member dynamics on their energy consumption habits. While some research has explored energy consumption in rural areas, there is a notable lack of qualitative studies that delve into the lived experiences and energy habits of rural older residents. This study addresses this gap by providing both qualitative insights and quantitative data on how household dynamics, individual habits, and architectural characteristics influence energy use and thermal comfort. At the policy level, the Chinese government has introduced several initiatives in recent years aimed at improving living conditions in rural areas, such as the “Rural Revitalization Strategy”, which includes measures to enhance rural infrastructure, housing conditions, and promote the use of clean energy [21,22]. However, during policy implementation, it has been observed that low-income households often struggle to afford the high costs of clean energy, and the sustainability and targeting of subsidy programs remain insufficient, which has limited the overall effectiveness of these policies [23].

This paper aims to understand the occupant energy use behaviour of the older population in China’s cold climate zone and the impact of household characteristics and socio-economic variables on energy consumption in the home. The objectives of this study are as follows:

• To understand indoor environmental conditions and occupant daily behaviour in the homes of older people in rural China.
• To establish quantitative relationships between specific environmental factors and the energy use behaviour of older occupants to achieve summer thermal comfort.
• To qualitatively study the impact of key socio-economic variables (like income levels, and educational background) on building energy consumption and the daily living needs of the older population.

2. Materials and Methods

This case study focuses on a representative village in the cold climate zone of southwestern Linyi City, Shandong Province. The village has 306 houses, of which 278 are occupied, indicating about 90% occupancy. Older residents live in 118 houses, while the remaining 160 are occupied by other demographic groups. Older couples make up 58% of the households, individuals living alone account for 25%, and three-generation households are relatively rare at 10%. These living arrangements provide a basis for selecting five types of older households: three generations living together, older people living with grandchildren, older people living with children, older couples, and individuals living alone. Each type represents a portion of the village’s demographic structure and offers a sample of the rural older population’s varied living conditions and energy use patterns.

This study uses a mixed-method approach to explore energy consumption and fuel poverty among older adults of low socio-economic status in rural areas. Data collection included indoor environmental monitoring and questionnaire surveys, with interviews conducted on the last day of the week-long monitoring period to minimize any conscious behaviour changes that might affect the results. This timing also helped build trust and familiarity between the researcher and participants. To gain deeper insights, face-to-face interviews were conducted to observe non-verbal cues, with each session recorded, transcribed verbatim, and translated into English. Given the high illiteracy rate among older rural residents, the researcher assisted in completing the questionnaires. Quantitative indoor monitoring was conducted using HOBO UX100-003 data loggers for their high accuracy (±0.21 °C for temperature, ±3.5% for humidity) and cost-effectiveness (

Table 1. Instrumentation and data collection parameters for on-site monitoring.

Parameter	Data Logger	Accuracy	Interval
Indoor temperature	HOBO UX100-003	±0.21 °C	5 min
Indoor relative humidity	HOBO UX100-003	±3.5%	5 min
Outdoor environmental conditions	China Meteorological Administration		1 h

). Together, the quantitative and qualitative data provide a detailed understanding of indoor environmental conditions and energy use behaviours across diverse household types.

This study focuses on older participants, defined as individuals aged 60 and above, in accordance with the Chinese government’s legal definition of old age as stipulated in the Law of the People’s Republic of China on the Protection of the Rights and Interests of Older Adults. As previously mentioned, many rural areas in China are experiencing significant ageing due to younger generations migrating to urban centres, leaving a large proportion of older adults behind in these regions. Given the demographic shift and the unique challenges faced by older residents in these regions, focusing on this age group provides valuable insights into their living conditions and energy use behaviours. It is important to note that in rural China, older adults are not typically considered retirees, as formal retirement is a concept more relevant to industrialized urban societies. Instead, many older residents continue working out of necessity, while some voluntarily participate in the New Rural Social Pension Insurance (NRSPI) system. These participants are capable of living independently and healthily, ensuring that the data collected are representative of the active older population residing in the village. Two households of each type from five different types of older households, for a total of ten households, were selected as the research sample. The personal characteristics and housing details of respondents across these five types of households are comprehensively presented in Table 1, where each of the ten surveyed households is assigned a unique identifier for detailed analysis in the Conclusions Section.

Data collection was conducted in the summer of 2023, from 1 August to 5 September. Given the limited availability of data loggers, two devices were placed in the living rooms of two houses of the same type. Each week, the data loggers were moved to a different household type, continuing for five weeks to cover all five types of older households. Although this approach meant that different household types were monitored at different times, it was necessary due to the limited number of sensors.

As shown in

Table 2. Household types and corresponding floor plans with data logger locations.

Household Type	Monitoring Location 1	Monitoring Location 2
Three generations living together	TGL-01	TGL-02
Older people living with grandchildren	OLG-03	OLG-04
Older people living with children	OLC-05	OLC-06
Older couple living together	OCL-07	OCL-08
Older people living alone	OLA-09	OLA-10

and the household floor plans, the data loggers were mounted at a height of 1.8 m on specific walls within the living rooms or bed–living rooms, marked with orange circles. This placement was carefully chosen to avoid direct sunlight and proximity to windows to minimize the effects of external influences. This study focused on monitoring living rooms, as they are typically the most communal indoor spaces where household activities are concentrated. In some northern rural homes, multifunctional spaces combine the living room and bedroom, referred to as bed–living rooms, such as in households TGL-01, OCL-07, OLA-09, and OLA-10. These households are expected to show more complex environmental fluctuations due to the extended use of the space for nighttime rest. The primary focus of this study is to compare the indoor living conditions of each household type with the actual outdoor climate during the measurement periods, rather than comparing the fabric response of homes under identical climate conditions. Therefore, measuring at different times is acceptable for capturing the living conditions of older adults in different familial settings.

Qualitative insights from interview responses support the quantitative data obtained from measurements and surveys. This combined analysis helps in identifying energy use behaviour and influencing factors specific to different types of older households. The intent is to draw correlations between the lived experiences of older people, as captured in interviews, and the empirical data from environmental monitoring and surveys.

3. Results and Discussion

Table 3. Information of 5 types of older respondents.

Household Type	House ID	Personal Characteristic				House Information
		Gender	Age	Income (CNY Per Month)	Education	Building Type
Three generations living together	TGL-01	F	80+	Less than 1000	Illiterate	Brick–concrete structure
	TGL-02	F + M	60–65	Over 5000	Junior high school	Brick–concrete structure
Older people living with grandchildren	OLG-03	M + F	60–65	4000–5000	Junior high school	Brick–concrete structure
	OLG-04	F + M	60–65	2000–3000	Junior high school	Brick–concrete structure
Older people living with children	OLC-05	M + F	60–65	Over 5000	Illiterate	Brick–concrete structure
	OLC-06	F + M	60–65	3000–4000	Primary school	Brick–concrete structure
Older couple living together	OCL-07	M + F	71–75	Less than 1000	Junior high school	Brick–concrete structure
	OCL-08	F + M	71–75	2000–3000	High school	Masonry structure
Older people living alone	OLA-09	M	71–75	1000–2000	Primary school	Brick–concrete structure
	OLA-10	F	71–75	Less than 1000	Illiterate	Brick–concrete structure

delineates the personal characteristics, architectural information, and locations monitored by data loggers for the five types of respondents.

Upon analysing the environmental factors of both residences over a week in summer, as depicted in Figure 1, the households TGL-01 and TGL-02 with three generations living together exhibited daily temperature and relative humidity patterns that fluctuated in tandem with the external environment. However, the two households showed distinct differences in thermal performance, reflecting how household dynamics, building characteristics, and energy use behaviours influence indoor comfort.

TGL-01 represents an 83-year-old woman’s living space, which serves as a combined living, dining, and sleeping area, separated only by wardrobes. This space exhibited a more stable temperature curve compared to TGL-02, with consistently lower indoor temperatures, averaging 2 °C lower throughout the week. The relative humidity in TGL-01 was higher, likely due to the resident’s daily activities, such as placing water basins in the room and cooking, which contributed to increased humidity levels. The resident’s cooling behaviour was characterized by natural ventilation—doors and windows remained open all day, and she rarely used electric fans, as she described:

“When it’s not too hot, I return to my bedroom to sleep, always keeping the doors and windows open. I also have an electric fan and a cool mat, making for a comfortable living situation.”

The dwelling benefits from a 2 m shaded porch, which reduces solar heat gain, and the architectural insulation is effective. However, no curtains are installed to manage sunlight directly. During times of excessive indoor heat, she relocates to an air-conditioned bedroom for cohabitation with her children. This relocation helps her manage thermal discomfort:

“In recent days, I’ve been spending my daytime in my son and daughter-in-law’s bedroom. Their room is much cooler with the air conditioning on.”

During the interview, the resident emphasized her conservative approach to energy use and reliance on her family for cooler accommodations:

“Ever since my son and daughter-in-law returned from the city to live with me, the air conditioning has been on every day in the summer, costing over 200 yuan in electricity this month. I used to cover the energy costs myself, and even though my son has started to pay the electricity bill, I still cringe every time the fan or air conditioner is turned on.”

In contrast, TGL-02 represents a 60-year-old woman’s living room, which exhibits a longer thermal lag—slower to reach peak indoor temperatures following the peak outdoor temperatures—compared to TGL-01. Despite both households employing a combination of natural ventilation and electric fans, TGL-02 consistently showed more volatile temperature curves and lower relative humidity, with indoor temperatures remaining approximately 2 °C higher than TGL-01.

Several factors contributed to TGL-02’s thermal profile. The 7.5 m by 3 m conservatory in the household reduces direct solar gains but retains more heat. Additionally, the living room experiences greater internal heat gains from family activities and appliance use—the TV, computer, air conditioning, and other electronic devices frequently generate heat, particularly in the evening when the family gathers:

“Around 7 o’clock, our family gathers in the living room for dinner, and my grandchildren spend several hours watching TV in the living room during their summer holidays.”

The larger window area in TGL-02 also results in more solar radiation entering the room, increasing the overall thermal load. The room’s larger space and window size leads to TGL-02 taking longer to cool down after outdoor temperatures drop.

The resident of TGL-02 detailed a more comfortable financial situation, which allows for the use of air conditioning when deemed necessary:

“When I feel hot, I go back to my bedroom and turn on the air conditioning. If it’s not too hot, I just use the fan. Compared to other villagers, my living conditions are better in many aspects.” She acknowledged that her better financial status affords her greater comfort in energy use, and she expressed disbelief at how other villagers manage without such amenities: “I don’t know how others tolerate the heat. I can’t bear it.”

The quantitative data support these qualitative insights, illustrating how energy behaviours, family dynamics, and building design affect thermal comfort. TGL-01 shows lower indoor temperatures and higher humidity, a result of consistent natural ventilation and household activities that introduce moisture. This cooler indoor environment, despite the summer heat, can be attributed to the shading provided by a 2 m porch and the smaller, less complex layout, which minimizes internal heat gains. Additionally, TGL-01 has fewer electrical appliances and less occupancy-related heat, which helps maintain a lower temperature.

In contrast, TGL-02 experiences greater temperature fluctuations and lower humidity due to its larger space, more appliances, and increased internal gains from family activity. TGL-02 takes longer to reach peak indoor temperatures compared to outdoor peaks. This is likely due to the conservatory, which retains heat, and the greater thermal inertia of the larger room size. The internal heat gains in TGL-02 from family members, electronics, and evening gatherings are reflected in the higher and more volatile indoor temperatures. By contrast, TGL-01’s reliance on natural cooling methods and occasional relocation to air-conditioned rooms result in a more stable indoor environment.

These findings underscore how energy behaviours, building features, and socio-economic status shape the thermal environment in rural households. TGL-01’s lower energy consumption reflects the resident’s thrifty energy use approach, while TGL-02’s more active use of electrical appliances and family activities contribute to higher temperatures and internal gains.

Figure 2 presents the environmental conditions within two residences of older couples living with their grandchildren, OLG-03 and OLG-04. Both households exhibited daily temperature patterns that correlated with outdoor temperature fluctuations, with some inherent thermal lag between indoor and outdoor peaks. OLG-03, home to a 65-year-old man and his wife who share their space with their teenage grandchildren, displayed a more volatile temperature curve compared to OLG-04, likely due to the dynamic space usage and the presence of multiple generations within the household. The multifunctional nature of the space—used for living, dining, and sleeping—along with activities such as cooking and door usage, contributed to indoor temperature and humidity fluctuations. The home’s reliance on an open iron door for ventilation and sunlight, combined with the lack of south-facing windows, results in an appropriate level of cross-indoor natural ventilation that reduces the perception of heat.

The interviews reveal how economic conditions influence older people’s choices in forgoing their own thermal comfort to provide for thermal comfort for their grandchildren:

“On exceptionally hot days when we go out to do farm work, the kids turn on the energy-saving air conditioner, which has a lower electricity cost. But if they are at school, we don’t use the air conditioner; just a fan is sufficient for us.”

The resident’s quote highlights a pattern of adjusting energy consumption based on family members’ needs, contributing to more significant internal temperature fluctuations during the day. The descriptive statistical analysis generated from Figure 2, particularly the blue curve representing OLG-03 from 10 August to 14 August, supports the interview responses regarding energy use behaviour. The fluctuating daytime temperature curve confirms that OLG-03’s temperature is generally higher when the family is active, occasionally even exceeding outdoor temperatures, but shows brief and noticeable drops due to the use of air conditioning.

In addition to the challenges of the need for cooling, the couple faces energy poverty when it comes to cooking, relying on free firewood and straw instead of using a gas stove. Their frugal lifestyle is reflected in the daily temperature profile, which shows a more pronounced increase in indoor temperature during periods of direct sunlight and activity within the home.

OLG-04, monitored in the living room of a 61-year-old woman, reveals a more consistent internal environment with no significant temperature fluctuations, which is supported with the resident’s admission that she frequently uses air conditioning:

“When it’s above 30 °C in the summer, whether during the day or night, I will turn on the air conditioning in the living room or bedroom.”

The stable indoor temperatures suggest that air conditioning is indeed used frequently, as supported by the resident’s lifestyle, despite the fact that she does not pay the energy bills herself. The financial support from her children, who have moved to the city, allows her to use cooling appliances liberally:

“The energy bills are certainly not minor, but all the expenses are paid by my children, and I’m not aware of the exact amount.”

This contrasts sharply with OLG-03, where financial necessity dictates a more frugal use of energy for cooling.

In both households, the presence of grandchildren and the varying levels of financial freedom play a significant role in shaping energy use patterns and indoor environmental conditions. OLG-03 shows greater variability in indoor temperature and humidity, driven by the need to economize on energy and the dynamic use of space by multiple generations. Meanwhile, OLG-04 enjoys a more stable thermal environment, enabled by financial support from the resident’s children, allowing for a more liberal use of air conditioning without concern for the cost.

These narratives illustrate the heterogeneity of energy awareness and financial limitations that shape the living conditions and thermal comfort strategies in rural older households. The temperature profiles in both OLG-03 and OLG-04 provide a clear picture of how household dynamics, socio-economic factors, and energy behaviours influence the thermal environment in rural settings. In OLG-03, the emphasis on energy-saving measures leads to more noticeable fluctuations in indoor temperature, while in OLG-04, financial comfort allows for a more stable and controlled thermal environment.

Figure 3 displays the environmental conditions within two cohabitation residences, OLC-05 and OLC-06, where older individuals reside with children. OLC-05 is the abode of a 62-year-old male and his spouse, who share this newly constructed modern edifice, completed in 2022, with their second son. It is a three-storey building featuring large double-glazed fenestrations without draperies, which account for the observed minimal fluctuations in indoor temperature and humidity, with an interior temperature peak at 33.08 °C. The consistent indoor temperature of OLC-05, as shown in the blue curve in Figure 3, reflects the building’s efficient thermal performance. This stability can be attributed to several architectural and material choices: the structure is built with load-bearing porous concrete bricks that provide effective insulation, while the doors and windows are constructed from titanium alloy with double-glazed glass, significantly reducing heat transfer. The tiled flooring adds thermal mass, and the large eaves provide shading, helping to block direct sunlight during peak daytime hours. Additionally, the larger room sizes contribute to a more even distribution of heat, reducing sudden temperature spikes. These design elements collectively create a thermally efficient envelope that minimizes heat gains during the day, allowing for a comfortable indoor climate without frequent reliance on active cooling. The stability of the temperature curve further suggests that natural ventilation and the thermal mass of the structure effectively buffer against outdoor temperature fluctuations. This is reinforced by the resident’s comments:

“I find it quite comfortable and have never felt it to be excessively hot. On particularly sweltering days, we use an electric fan in the living room.”

The resident’s perception of comfort aligns with the quantitative data, which show only minor fluctuations in indoor temperature despite the variations in outdoor temperature.

In contrast, OLC-06, a conventional single-storey construction, shows more pronounced temperature variations, as depicted by the orange curve in Figure 3. The dips in the curve indicate the use of air conditioning to manage indoor heat, especially during the periods of peak outdoor temperatures on 17 and 18 August. The occupant confirmed this reliance on active cooling:

“Summers are certainly hot. We switch on the air conditioner in the living room.”

The quantitative data support this claim, as there are clear drops in temperature corresponding to the activation of the air conditioning unit during the hottest periods of the day. The fluctuations in the OLC-06 temperature curve, compared to the stability of OLC-05, highlight the influence of older construction and less effective insulation on the need for cooling appliances to maintain indoor comfort.

Despite the temperature variations, the resident of OLC-06 does not perceive energy costs as burdensome, noting that while the air conditioning is used frequently, the cost is acceptable. Additionally, the resident occasionally uses a traditional stove, which further reduces their overall energy expenditure for cooking:

“Ordinary life doesn’t make me perceive energy costs as excessive; these are essential energies that must be used. Even though I possess a gas stove, there are times I opt to use the traditional stove to burn firewood and straw for cooking.”

The modern infrastructure of OLC-05, on the other hand, allows the family to maintain comfortable indoor conditions without the frequent use of air conditioning, as evidenced by the consistently low and stable indoor temperatures. The quantitative data reinforce this, showing how the efficient building design of OLC-05 reduces reliance on active cooling, resulting in a more passive approach to temperature regulation. In contrast, OLC-06 requires active cooling measures, such as air conditioning, to mitigate the effects of less efficient insulation and construction materials, which are reflected in the more volatile indoor temperature patterns.

Figure 4 presents the environmental conditions within and outside two residences, OC-07 and OC-08, inhabited by older couples. In this village, older couples living together represent the most common household type, as their children have migrated to cities, leaving the older couples to continue living in the village. Residence OC-07, home to a 75-year-old male and his spouse, is a modest living space of only 33 square meters, the smallest among the interviewees. The space is divided into a bedroom, living, and dining area, partitioned only by wardrobes, and lacks modern sun-shading devices such as curtains or blinds. The metal doors and windows provide minimal insulation, contributing to the consistently higher indoor temperatures seen in the data. Throughout the week, as shown in the temperature chart, the indoor temperatures remained above the outdoor levels, with peaks reaching as high as 34.1 °C, particularly on 24 August. This significant heat retention suggests that the structure of the home, combined with the absence of air conditioning, results in poor thermal performance.

The resident of OC-07, who does not use air conditioning, relies on basic natural ventilation to manage indoor heat, as described in the interview:

“When it gets extremely hot, I turn on the electric fan and strip down to the waist. Although I have a handheld fan, I seldom use it due to laziness.”

This aligns with the quantitative data; even with external temperature dips during the night, the indoor temperature remains relatively high, as the fan alone is insufficient to effectively dissipate heat. The lack of advanced cooling devices and modern insulation in OC-07 leads to persistent discomfort, as evidenced by the resident’s minimalist approach to thermal management.

Furthermore, the economic limitations of OC-07’s residents are reflected in their energy use patterns. With no financial support from their children who have migrated to the city, the couple remains highly aware of their energy expenses, facing energy poverty. Although they own a gas stove, they primarily use a traditional biomass-fuelled stove, burning straw and firewood to cook. This is confirmed in their statement:

“My energy expenditure is quite modest. For cooking gas, I use only three canisters a year, as I predominantly cook with a traditional stove using free straw or firewood. Electricity costs me less than 20 yuan per month, and water is about 130 yuan annually.”

On the other hand, OC-08, home to a 72-year-old woman and her partner, demonstrates a more controlled thermal environment due to the use of air conditioning. The residence is an over-two-decade-old traditional single-storey masonry structure with a sloping roof and a porch. The temperature chart shows a clear pattern of air conditioning use, with the indoor temperature stabilizing during the day when the air conditioner is active. The chart reflects a notable difference between indoor and outdoor temperatures, particularly between 22 August and 26 August, with the air conditioning mitigating heat. After 24 August, a noticeable cessation of air conditioning use is observed, likely due to the significant drop in outdoor temperatures, which reduced the need for cooling appliances.

The resident of OC-08 corroborates this behaviour, explaining how air conditioning provides comfort even during extreme heat:

“When it’s hot outside, I don’t feel the heat once inside, as the air conditioner is on.”

Despite the perception that electricity is costly, the resident prioritizes maintaining a comfortable living environment, emphasizing the importance of air conditioning for thermal comfort, as she explains:

“Air conditioning is only used for about a month in the summer, with this month’s electricity bill around 200 yuan and around 50 yuan in other months.”

While electricity costs are a concern, the residents of OC-08 are willing to bear these expenses for the sake of comfort, in contrast to OC-07, where energy conservation is prioritized due to financial necessity.

The comparison between OC-07 and OC-08 highlights the stark contrast in thermal comfort strategies and energy consumption behaviours. OC-07’s reliance on passive ventilation, combined with minimal insulation, results in consistently high indoor temperatures, whereas OC-08 benefits from active cooling, leading to more stable indoor conditions. The differences in energy consumption behaviour between these households reflect the broader socio-economic disparities and the varying levels of thermal comfort achieved through different energy strategies. This analysis underscores the role of socio-economic factors in shaping thermal comfort in rural older households. While OC-08 can afford to use air conditioning to manage indoor temperatures, OC-07’s limited financial resources and reliance on traditional, low-cost energy solutions like biomass stoves force them to endure higher temperatures and reduced thermal comfort.

Figure 5 illustrates the internal and external environmental conditions of residences OLA-09 and OLA-10, occupied by solitary older individuals, serving as the base case studies for the five distinct types of elderly dwellings examined in this research. Both homes demonstrate diurnal cycles of temperature closely aligned with external environmental patterns, relying extensively on natural ventilation through open doors and windows, combined with the use of electric fans for cooling.

Quantitatively, the temperature curves for both homes show a close correlation with outdoor temperatures, highlighting their reliance on passive ventilation. OLA-09, represented by the blue curve, experiences larger temperature fluctuations throughout the day, with peaks reaching approximately 33 °C on 4 September. These fluctuations are more pronounced than in OLA-10, indicating a greater exposure to external environmental conditions due to the minimal insulation provided by the oiled paper windows rather than glazing. This lack of thermal buffering leaves the indoor temperature vulnerable to rapid increases during mid-day heat, a common issue in structures with insufficient insulation. The resident confirms his approach to managing this heat:

“During summer, there might be a month that’s quite hot, and I generally keep the doors open all day for good air circulation. I have two fans; when guests come over, I’ll turn on the big ceiling fan. For myself, a standing fan is sufficient.”

This practice, while promoting airflow, leads to more significant swings in temperature throughout the day, reflecting the limitations of natural ventilation in providing consistent indoor comfort. The graph highlights how during peak outdoor heat, OLA-09’s indoor temperatures are almost parallel to the external conditions, demonstrating the minimal thermal resistance of the building structure.

The older individual, having lost his spouse, now shoulders the energy bills alone without financial support from children. To economize, he resorts to traditional free stoves, leaving the residence with minimal electrical appliances:

“I rarely cook with gas. Mostly, I cook with a traditional stove burning free straw and firewood from my own fields.”

On the other hand, OLA-10, represented by the orange curve, shows slightly lower temperature peaks and a more stable indoor temperature profile, particularly during the hottest periods. This stability is due to better insulation in OLA-10, resulting in a longer thermal lag—the time it takes for indoor temperatures to respond to changes in outdoor conditions. The lag is evident during the peaks on 4 September, where OLA-10 maintains a more moderate temperature compared to OLA-09, indicating that the building’s insulation slows the heat transfer, preventing rapid indoor temperature spikes. Despite having financial support from her children, which would allow for more energy use, the resident of OLA-10 still refrains from using air conditioning, adhering to habits of frugality:

“At night, if it’s too hot to sleep, I turn on the electric fan, which my son just bought for me this year. All the energy and communication expenses are paid for by my son.”

This decision reflects a deep-rooted approach to energy conservation, despite the availability of modern cooling technologies and financial resources, further emphasizing the balance between thermal comfort and traditional habits of energy savings.

A notable difference between the two homes is the resident’s level of financial independence and their access to resources. OLA-09’s resident, who lives alone with minimal financial support, resorts to basic methods for cooling and cooking, relying on a traditional stove burning free straw and firewood for daily needs. This lifestyle leads to low energy consumption, as evidenced by the greater indoor temperature variability and lack of reliance on energy-intensive appliances. By contrast, OLA-10, though similar in indoor temperature trends, has better insulation and a more comfortable living environment due to the resident’s children’s financial support. Nevertheless, the resident still limits her use of electrical appliances, reflecting cultural norms and a preference for lower energy usage.

The comparison between OLA-09 and OLA-10 reveals how building materials, ventilation strategies, and personal habits influence the indoor thermal environment. OLA-09’s higher temperature peaks highlight the vulnerabilities of buildings with minimal insulation, while OLA-10’s stability illustrates the benefits of passive cooling strategies combined with adequate building insulation. These findings suggest that improvements in building design, such as installing proper insulation or upgrading windows, could significantly enhance thermal comfort for older residents who rely on natural ventilation. Moreover, the residents’ frugal energy practices—whether by necessity or habit—further contribute to the limited use of modern cooling technologies, showcasing how cultural and financial factors intertwine to shape energy consumption behaviours in these rural households.

4. Conclusions

Research on the occupant behaviour of China’s rural residents shows that although rural buildings have the highest energy use intensity, they still fail to meet the thermal comfort requirements of occupants [24]. Through the implementation of surveys, interviews, and observations, this study evaluated five types of older households to understand their indoor environmental conditions and daily behaviours. Employing a mixed-method approach, both quantitative and qualitative, this research explored the environmental factors and socio-economic variables affecting the daily energy consumption behaviours of different types of older inhabitants in low-income rural areas of Shandong, China. This investigation provides insights for future rural housing designs that should be energy-efficient, cost-effective, and climate-adaptive, thereby improving the living conditions of older people. Additionally, this study emphasizes the importance of considering household dynamics, individual habits, and architectural characteristics in the formulation of strategies for energy usage and thermal comfort. Such an approach has the potential to address the high energy consumption of rural residential buildings.

• Future Research

Future studies should explore similar energy consumption patterns in other regions with different climate conditions to better understand the diverse environmental and socio-economic challenges across rural China. Additionally, future research could expand the scope of indoor data collection by including additional parameters such as indoor air quality, specifically monitoring CO₂ concentrations and NO levels. Employing dynamic behaviour tracking tools would also enable a more accurate recording of residents’ real-life activities. Installing data loggers on energy-consuming appliances could provide precise measurements of the duration and frequency of appliance usage, and monitoring electricity meters could offer more accurate readings of total household energy consumption. These enhancements, along with longer-term monitoring across different seasons, could provide a more holistic view of rural energy challenges, particularly in extreme weather conditions. Exploring households with varying income levels and family compositions would further deepen the understanding of how these factors influence energy use behaviours and inform more targeted interventions.

• Limitations of This Study

This study had several limitations. First, the data collection was conducted over a short period in the summer of 2023, which may not fully capture seasonal variations in energy use and thermal comfort, especially during the winter months when heating requirements are higher. Additionally, this study did not include key factors such as indoor air quality or the energy consumption related to biomass cooking, which limits this study’s full accounting of household energy use. Due to the limited number of data loggers, each household type was monitored at different times, which may have introduced slight variations in environmental conditions. More accurate data on appliance-specific energy consumption would require the installation of device-specific data loggers. Moreover, the focus on a single village in Shandong Province may limit the generalizability of the findings to other rural regions of China with different economic and climatic conditions. Finally, the reliance on face-to-face interviews and questionnaires may have influenced participants’ responses, as they might have provided socially acceptable answers.