Evaluating the Nexus between Housing and Energy Sectors: The Comparison of Urban, Peri-Urban and Rural Housing Areas in Zhuhai, China

China has developed several housing policy reforms and has, in recent years, progressed further on developing policies to promote green strategies and energy-saving plans. The urban housing has much benefited from such reforms and plans, while rural housing has experienced minimal change in the past few decades. As a result, this study aims to identify and explore these differences, challenges, and implications that exist between three areas of urban, peri-urban, and rural in a particular case study in China. For this study, selected residential areas in the City of Zhuhai and its peri-urban and rural areas are selected as case studies. A questionnaire survey is conducted to analyze energy and housing conditions across the more prosperous urban, the dynamic and transitory peri-urban, and the less prosperous rural areas. The case studies are analyzed as comparative examples in a hot and humid sub-tropical area of Southern China. The study compares energy and housing conditions and argues potential possibilities and challenges for the future development of housing policy reforms that are the result of current housing development patterns and green strategy situation in China.


Introduction to Housing Sector in China
Housing is a significant part of the built environment. In the past three to four decades, the Chinese housing system has drastically changed from one dominant Energy and Power Engineering type of public housing to private house ownership [1]. This includes new development of mid-rise housing, high rise apartments, gated residential communities, and a cluster of low-rise luxury housing (locally known as villa housing) [2].
In regard to this process, Logan et al. [3] argue two new ways of housing reform; 1) "privatization of public housing"; and 2) "development of new private housing sector". Since 1949, both ways are new to the context of China but have grown immensely at different times and throughout different housing reforms.
Additionally, the change in the Chinese housing pattern system and development patterns has a major impact on the overall change of household energy consumption, change of living lifestyle, and change of well-being and quality of life in the living environments [4] [5] [6] [7]. The impact on the geography of space determines the way residents' living and consumption patterns are shaping. This is, in particular, important to China due to its pace and scale of development and growth. More specifically, there are impacts on non-urban areas that should be taken into consideration. We could refer to these as possible challenges on urbanization and urban development that require careful planning in the next reforms, urbanization plans, and development modes [8].
While in recent years most research on Chinese housing has been on price increase [9]- [15], issues of affordability [16] [17] [18], sustainability [6] [7] [19] [20] [21] and structure of housing development [22] [23] have become critical matters to China's current conditions and the future phase of development. Some of these studies are developed from earlier critical analysis of China's housing issues, such as inequality in Urban China [24] [25], multiple stakeholder analysis of benefits [3], housing quality differences [26], market transitions [27], etc. In recent transitions, there are clearly issues of housing inequalities not only between different Chinese cities [28], but also between different areas of the city environments, such as urban, peri-urban, and rural areas of municipalities. This reflects on real estate market supply and demand function [29] [30] as well as efficiency of market [31] [32] [33], development mode in different locals, market-driven mechanisms, and pro-developer approaches to growing urbanisation [34]. Also, the differences between cities of different sizes and their markets are highlighted in China's recent urbanization plan, called New-Type Urbanization Plan (NUP) [35]. Hence, there are certain transitions that could be taken into consideration for the housing sectors. These transitions are studied through various possibilities, such as housing differentiation issues [36], economic policy uncertainties [37], housing market dynamics [38], dynamics and inequalities in energy efficiency [39] [40] [41], green housing transition [42], the impact of housing price on non-housing matters [43], etc. Some of these could be verified through different structural transitions [44], changes in institutional arrangements or structure [22], socio-economic development and land-use change [45], as well as issues of urbanisation [34] [35], and different scales [46] or spatial levels [47]. For instance, China's "transition of the housing model from an administrative system to a market-oriented system" [48] has changed the social structure in many new developments and is continuously having a major impact on

China's Energy Issues and Housing
The steady rise of urbanization has a direct impact on housing development in the urban, peri-urban, and rural areas. This has been developed even further in the latest urbanization plan introduced in 2014 [34] [35]. In comparison with the Western standards, energy use in housing has been insignificant [51]- [57] but the substantial increase in the past few decades has become one of China's major energy issues [35]. This challenge adds to China's energy load, increasing cooling and heating demand [58] [59], as well as issues of energy supply. The Energy Conservation Law (ECL) in 1997 and then the following policies on the green building since 2000 can be considered as the starting points in recognizing the position of household energy consumption in housing construction. Since then, the policy reform on housing energy efficiency has been insignificant but has now become part of China's 12th five-year plan (the previous FYP), the recent 13th five-year-plan, and highly likely in the forthcoming ones. The three pillars of "energy efficiency", "low carbon", and "green development" in China's 12th and 13th FYP are considered as a direct prescription to the current energy issues in China's construction sector. With the progress on context-specific building code and life-cycle data, the gap in current research on China's housing and energy remain valid and important. As a result, context-specific studies are essential to identify energy-related attributes that are part of future design specification, household energy demand, and consumption. More importantly, a multi-scalar comparison as studied in this research paper could highlight gaps, issues, and implications in different locales and at different spatial patterns [60] A areas of urban, peri-urban, and rural of a selective city. This is conducted through on-site surveys rather than the usual methods of statistics-based analysis. This approach is believed to be less generic and more representative of the case study areas.

Objectives of the Survey Study
This is a context-specific housing study for a sub-tropical hot and humid condition in Southern China. Based on existing conditions and patterns of development in three spatial categories of urban, peri-urban, and rural, this study firstly explores the conditions of residential units and then provides a set of data for primary household energy uses during warm and cold seasons. The collected data are then analyzed for further cross-analysis. The questionnaire survey covers several aspects of housing conditions and energy consumption patterns. The survey study is essential for such a study as it includes an observational method to the conditions of housing and living environments. A cross-comparison between housing models of urban, peri-urban, and rural regions promotes a comprehensive understanding of the living conditions and energy-related issues across different social classes of one context. The questionnaire survey includes three attributes of "housing occupancy", "housing typology", and "seasonal household energy consumption".
The objectives of the study are: 1) to develop a cross-analysis between urban,

Methodology
This survey study was conducted in eight consecutive days in multiple spatial areas of the city of Zhuhai, south of China. This example is selected based on its hot and humid climatic conditions, growing urbanization, and increasing energy demand (mainly for cooling). The methodological approach includes both questionnaire and observational study of selected residential areas. The participants of the study are residents of three spatial categories in one region, i.e. urban, pe- The study intentionally does not use statistical data on the consumption of energy resources and sampling as such data often are generic across all social groups of different backgrounds. In existing studies, the statistical data suggest general results that may not be truly representational of different social groups.
In light of this matter, the depth of demographic differences could not be simply highlighted through statistical data and analysis. Hence, the study's data collection is based on multiple case studies initially taken from 16 locations across one city example and in three different study areas of urban, peri-urban, and rural.
In this study, to reduce the risk of generating bias, the representative case study areas were then selected. From the initial eight urban areas, four representative study areas are selected to ensure consistency and accuracy across collected data.
Similarly, from the initial four peri-urban areas, two representative study areas are selected to ensure selection is made based on accurate and unbiased collected data. This is also repeated for rural areas, where four case examples were studied, and two representative study areas are then selected. In this regard, the data is assessed across all cases in each category (i.e. urban, peri-urban, and rural) to ensure only selecting the ones unbiased and consistent. This selection is made by voiding half of the case studies, ensuring that each case study example is consis- per case study example. This has taken into consideration a 10% potential inaccuracy, which is already voided from the data analysis.
The schematic diagram below ( Figure 1) represents the study's methodology in four stages. In stage 1, the study starts with a general case study selection based on three specific context areas and demographic categories, which is then assessed through a general survey study. The on-site survey was conducted during eight consecutive days (2 case study per day), through which three main factors were assessed, namely 1) demographic characteristics, 2) general survey of Figure 1. Schematic diagram of flow chart for the research study stages from general case study selection to on-site survey, sampling of case study selection, and detailed analysis. which is a selection of half of the originally studied cases. Finally at stage 4, a detailed analysis of the data is conducted to provide a representative sampling of the case study areas across three studied areas of urban, peri-urban, and rural.

Case Study Overview: Zhuhai's Urban, Peri-Urban and Rural Study Areas
The The city's steady economic growth and attraction for tourism activities in recent years, has helped to promote the city's restructuring as a major urban hub.
In return, the population for the city's temporary residents is increasing faster than before, which is studied for the period between 1979 and 2010 [64]. This indicates growing service-based and industry-based employment opportunities, including the job market in both the urban and the peri-urban areas of the city.
This demographic change is important to housing demand and construction of mass housing in some parts of the city.   For this study, the survey areas comprise: 1) four urban residential areas in Xiangzhou District; 2) two distinct peri-urban communities in between the city core and Jinwan District; and 3) two rural communities in the Western part of the city. These areas are shown in Figure 3, distributed in fringe areas of urban core zones where urban migration is booming and the housing market is increasing, peri-urban transitory areas between urban and outskirt areas, and rural areas outside the city's main areas and on the edge of the main city districts. The analysis is comparative between the three survey areas but is divided into three parts of "household occupancy", "residential conditions", and "seasonal household energy consumption". In doing so, the research findings provide a holistic overview of housing conditions, energy-related factors, and household demands in multiple scales of the city at three specific and different regions. In each part, the study provides a thorough evaluation of housing across three study areas, which are shown in the following sub-sections. The survey study includes 143 urban participants, 132 peri-urban participants, and 138 rural participants; who are all temporary and permanent residents in the selected study areas of Zhuhai.
This study is recognised as a sample-based study to represent housing conditions of specific parts of the city, and approach that could be utilised for future research or different locales.

The Analysis of Household Occupancy Conditions across Three Study Areas
The key factor to any housing survey is the analysis of its conditions, one of which is the occupancy analysis. In this part, all participants were asked about the number of residents in their properties. This is specifically important as the collected data indicates a clear overview of demographics in the three regions.
The study of housing occupancy is relevant and important to changes in patterns of demographics and energy consumption that are later discussed in the study.
The figure below demonstrates the overall data from the questionnaire survey on the topic of household occupancy (Figure 4).
In the studied urban residential areas, more than half of the participants live

The Analysis of Residential Conditions across Three Study Areas
Based on the survey studies, it is identified that there are significant differences in residential conditions of the three studied areas. Each of the three areas has distinct housing development patterns that are subject to detailed study and analysis. The relationship between living conditions and household occupancy can help us to better understand the patterns and demands that are emerging in each area. In this part of the study, the survey covers two aspects of residential conditions: the first is the analysis of the number of bedrooms in the residential units/houses, and the second is the number of stories for the surveyed residential units. These two aspects are both important to a better understanding of potential development patterns and living conditions across three study areas of urban, peri-urban, and rural. While there is a perceptible growth of China's urban housing stock, which is having a severe impact on shrinkage of rural housing [61], urban housing is significantly smaller than the ones in the peri-urban and rural areas. In the urban areas, most housing development projects for low to middle-class populations are comparatively smaller than in suburban and peri-urban areas ( Figure 5). This is due to the increasing rental and purchase prices in recent years. Similarly, Wang and Xu [66] have studied the case of China's housing prices and have analyzed the relationship between urban development and housing prices. In their study, the authors question the requirement for affordable housing as part of the sustainable development of China. This has become a more popular research trend in housing studies, some that touch on the issues of energy from the demand and supply perspectives.
Also in this study, it is evident that a trend in urban housing is towards 2 to 3 bedroom dwellings that are suitable for smaller and younger families. In the past two decades, the shift from a "socialist welfare system to a marketized system" Figure 5. Number of bedrooms for residential units in the studied areas of Zhuhai's urban, peri-urban and rural (Source: author's own data from the survey study). Similarly for the peri-urban, apart from the extended family housing, the majority of larger households that were studied were occupied by industrial labour groups and temporary workers. Yet, in the rural areas houses remain significantly larger due to the traditional family structure and living patterns. Although from the empirical data of the study, rural and peri-urban houses are relatively larger than urban housing, the trend in which the marketized housing system is developing in the urban areas is considerably better than the previous socialist welfare system. This is due to better maintenance and a more reasonable spatial configuration of living environments. Furthermore, the demand for smaller housing in the urban areas is deriving the urban housing market towards smaller housing units and compact development patterns.
Also as part of the housing analysis, the heights of residential units were observed and recorded ( Figure 6). In this respect, we can analyze an overall over-

The Analysis of Seasonal Household Energy Consumption across Three Study Areas
A major part of the survey study focuses on the analysis of seasonal household energy consumption that fits well with the previous analysis of household occupancy and residential conditions. Based on the questionnaire survey, four key primary sources of household energy consumption were identified in the region of Zhuhai, Southern Guangdong. Unlike many parts of China, gas usage is still cheap (due to subsidized prices) and popular for households. Apart from gas, electricity, combined electricity and renewable energies [69], Coal (also sometimes firewood) are some of the main sources of household energy consumption.
Nevertheless, consumption is different between urban, peri-urban, and rural areas. It is also significantly different between the two seasons of winter and summer.
During winter, the household energy consumption for gas is significantly higher in urban areas (Figure 7). On the other hand, in rural areas, gas consumption is minimal and is mainly replaced by coal (and firewood). Since heating is not required or is less required in the region of Southern Guangdong Province, the majority of household energy consumption during winter is for the purpose of cooking and lighting. Hence, gas usage is high for cooking and water heating. Figure 7 above indicates that electricity usage is similar between the three areas of urban, peri-urban, and rural. However, if to take into consideration the amount of usage based on energy consumption measurement, urban areas would have a higher percentage of electricity use in comparison with peri-urban and rural areas. One indicator and perhaps a major difference between rural and urban is the use of coal in cooking that is still very common in rural areas. Also during the study survey, it was observed that in the rural areas more solar panels are used for water heating. This is mainly related to the height of dwellings and the importance that the solar panels are more effective in low-rise housing. In the urban areas, only a few apartments in the higher floors of mid-rise and high-rise residential units can benefit from the use of solar panels. In general, the overall patterns between the three areas are very similar apart from differences in gas and coal usage. Rural energy development is still one of the crucial energy-related studies in the context of China. Previous studies [70] [71] [72] have discussed the topic of rural energy as part of China's policy reforms and development plans. As part of the seasonal analysis of energy consumption, the questionnaire survey also covers the energy usage of the summer period. This is studied predominantly because, during the summer period, household cooling is a major matter for the indoor thermal comfort of the residents. In general, household cooling becomes a major demand throughout the region, particularly that relative humidity is high during the summer period and the effectiveness of natural cooling is minimized. This increased demand for cooling changes the energy consumption patterns of all three contexts (Figure 8). The electricity usage uplifts substantially as the majority of households use either air conditioning or electric fans for the purpose of indoor cooling. In the compact areas, such as compact urban residential areas, this is expected to be higher. In summer, gas usage is no longer the primary source of energy consumption as it is mainly used for cooking and water heating. In rural areas, coal (also firewood) is mainly used for cooking purposes. While the gas usage in urban households is dropped during summer, peri-urban households have a slight rise in gas consumption. Electricity, however, remains the main source of household energy consumption. Renewable energies are not effectively operative for the purpose of cooling, and as a result, are mainly used for water heating purposes (i.e. solar panels). Overall, the comparison between seasonal energy consumption signifies the increasing demand for cooling during the warmer period of the year.

Results and Discussions
This study has touched on a few relative aspects of change in lifestyle patterns, demands and requirements, seasonal sources of energy consumption, and etc. In this study, the focus is on both "energy" and "housing conditions" in the context of Zhuhai. The comparison between the three areas of urban, peri-urban, and rural is necessary to identify the gaps and analyze the trends of housing development and requirements. In Chinese urban-rural studies, energy issues, including policy reforms, development, affordability, access, and security, identify   [20], which is proposed to improve China's current practices and technologies in building design and development [8] [35]. Yet, the current proposals are mainly focused on urban areas than rural. Therefore, there remains a substantial gap in housing reforms, strategy plans, and implementation mainly between the urban and the rural areas.

Complications and Challenges of Housing in China
This study provides a better comparative understanding of housing in three areas of urban, peri-urban, and rural. This is rarely done in research studies of cities, especially from the perspective of energy source and consumption analysis. This is done through a non-statistical analysis to reflect the realities of growing areas in city environments of developing contexts, particularly from the low-to-middle social classes. The collected data from the questionnaire survey covers the basic knowledge of housing conditions in these studied areas. The cross-analysis of data is aimed to identify the needs, demands, and trends that are subject to further detailed analysis. It is important to note these differences and take into consideration the transitions and potential gaps and opportunities in between housing developments in three specified areas of urban, peri-urban, and rural. Future research studies could learn from such differences and not generalize the results based on singular spatial levels, regions, or social classes.

Conclusions
This study identified key elements for housing conditions in the region of Southern Guangdong Province, in various areas in the region of the City of Zhuhai. As part of the specific survey study, the collected empirical data represent trends of development and housing conditions in various cases. The housing conditions between the urban, the peri-urban, and the rural are not only related to the visual dimension of the built environment but related to their occupancy, living styles/structures, energy source, and consumption. The study also pointed out the directions for current development patterns and the essential need for housing reforms. This study is also a suitable platform for energy-specific studies in the region of Zhuhai, where the focus is on measuring energy consumption, development of energy-saving plans, and improvement of housing's energy efficiency.
Furthermore, we can conclude how the current housing conditions can help policymakers to come up with strategies and energy saving plans that are comprehensive, detailed, and context-specific. Therefore, we can argue that the next housing reform in China needs to incorporate conditions of housing in all areas of urban, peri-urban, and rural, where various parameters and approaches are necessary for better implementation and development that are aimed for a more sustainable future. Based on the study survey and analysis of the collected data, it is important to consider three pillars of "affordability", "sustainability" and "design specifications" and develop them into a holistic framework of housing reform strategies that include various elements of living quality, energy-saving plans, and efficient design or even planning. Finally, it is important to consider the cross-contextual analysis of both energy and housing conditions in order to respond effectively to future housing and development strategies that are expected to include major elements of energy consumption plans, energy resource analysis, and low-carbon considerations. Energy and Power Engineering