1. Introduction
Climate change and carbon targets have evolved from scientific issues to political consensus and have most recently transitioned into a unified global effort [
1]. Buildings are essential in shaping and framing the future society, life, and environment in which people live, work, and interact. In addition, buildings play a dominant role in the transition to carbon-neutral societies and low-carbon energy systems [
2]. In 2022, buildings were responsible for 34% of the global energy demand and 37% of energy and process-related carbon dioxide (CO
2) emissions [
2]. Global building energy demand and emissions are still growing with rapid urbanization in emerging economies. According to International Energy Agency (IEA), to achieve the Paris Agreement goals, the global buildings and construction sector must achieve net-zero emissions, and all new buildings must be net-zero carbon starting in 2030 [
3]. Given the substantial increase in new construction activities in transitioning economies and the large scale of existing building stocks worldwide, policymakers must monitor emissions originating from and directly associated with the building sector. The mitigation of greenhouse gas (GHG) emissions from buildings must be a cornerstone of every national climate change strategy [
4].
In the context of low-carbon and clean energy transitions, increasing connections exist between the building and other sectors. The systematic integration of the building sector with the energy system is emerging in the context of low-carbon and energy transition. Consequently, this necessitates cross-cutting innovations in technology and regulatory mechanisms across sectors [
[5],
[6],
[7]]. For example, buildings are closely related to the industrial sector, especially in countries undergoing urbanization and rapid infrastructure development. During the construction phase, building materials produced by the industrial sector form the material inputs. Energy consumption and emissions from steel and cement production are conventionally calculated as part of those from the industrial sector [
8]. However, the primary catalyst for expansion in construction stems from the building sector, which should bear the responsibility for carbon emissions [
[9],
[10],
[11]]. Building construction has also increased the demand for transportation of building materials, resulting in higher energy consumption and emissions in the transportation sector. Collaboratively reducing carbon emissions in the building sector requires reasonable construction demand and processes, and efficient construction methods, in conjunction with efforts in the industry and transportation sectors [
12,
13]. Furthermore, electricity is the predominant energy source during the operational stages of buildings. However, with the transition to low-carbon energy systems, wind and solar power are expected to become the primary sources of electricity generation. The total amount, time of use, and flexibility of building demand, as well as power production from building-integrated photovoltaics (BIPVs) or building-attached photovoltaics (BAPVs), provide a strong and interconnected relationship between the building and power sectors [
14]. The substantial heating demand from urban buildings in northern China represents a challenge for the building sector in the country, especially considering the decreasing availability of combustion units in a future carbon-neutral society [
15]. The appropriate design of the power energy balance and utilization of waste heat from either combined heat and power (CHP) plants or nuclear plants in the power sector, or waste heat from industrial processes, will become increasingly critical in the future because of the limited availability of low-carbon heating sources [
16]. The complex integration of the building sector with other sectors presents major challenges for the future pathway design of carbon neutrality, both for top policymakers and research experts in various fields [
17,
18].
Moreover, the decarbonization of the building sector will yield numerous benefits to both the economy and society [
19]. The construction, renovation, and maintenance of buildings and their energy consumption systems, such as heating, ventilation, and air-conditioning (HVAC) systems, contribute significantly to a country’s gross domestic product (GDP) [
20,
21]. In addition, these processes represent a global average of 10% of country-level employment [
4]. The increasing installation of photovoltaic (PV) systems, integrated or attached to buildings, can stimulate the development of new businesses and job opportunities. Moreover, it can contribute to achieving other sustainable development goals, such as reducing inequalities and promoting sustainable cities and communities [
22].
Under the Paris Agreement, countries are required to volunteer nationally determined contributions (NDCs), which are subject to a five-yearly assessment process [
23]. The importance of decarbonizing the building sector is widely recognized, with 120 countries citing building energy improvements as a way to tackle emissions in their NDCs. As the world’s largest energy consumer, China accounts for 22% of the global energy consumption and 29% of total CO
2 emissions from fuel combustion [
24]. China’s evolving emission governance frameworks and decarbonization trajectory are positioned to exert transformative influence on global climate governance and emission reduction pace [
25,
26]. In 2020, China unveiled its new 2030 climate targets, aiming to achieve peak carbon emissions by 2030 and carbon neutrality by 2060. This is not only a strategic decision regarding sustainable development and global climate change mitigation but also an overarching action cluster encompassing all sectors of energy, resource conservation, and environmental protection [
27]. China has operationalized its carbon peaking and neutrality commitments through sector-specific action plans, including the building sector. This requires China’s building sector to achieve a carbon peak by 2030 and net-zero operational emissions by 2060 [
28].
Despite China’s ambitious policy declarations, critical gaps persist in the carbon neutrality pathways and step-by-step action planning [
29]. Hence, the main objective of this study was to investigate critical drivers and decarbonization levers in China’s building sector through integrated analyses and dynamic scenario modeling, proposing technological pathways and adaptive policy frameworks to achieve the carbon neutrality targets. Several studies have analyzed the emission reduction potentials and decarbonization pathways in the building sector at the national level. Langevin et al. [
27] used Scout, a reproducible and granular model of the United States (US) building energy consumption, to investigate the potential of the US building sector to reduce CO
2 emissions by 80% by 2050. Anandarajah et al. [
30] focused on scenario analyses of pathways leading to a low-carbon economy in the United Kingdom (UK) by 2050. Gambhir et al. [
31] analyzed the CO
2 emission pathways in India up to 2050 using the TIMES integrated assessment model. Zhou et al. [
32] investigated building energy consumption in China up to 2050, but did not discuss the technical demand from a carbon emission reduction perspective. Zhang et al.
[13] and Hu et al. [
33,
34] examined carbon emission reduction potentials in certain subsectors of China’s building sector, such as building construction-embodied energy and emissions, space heating, and space cooling, but did not provide a comprehensive decarbonization pathway.
Thus far, prevailing methodologies in this domain predominantly employ national-scale building energy and emission models coupled with scenario analysis frameworks to assess technological and policy interventions. A common approach is to establish a baseline scenario and then assess the energy savings and emission reductions achieved by various technologies relative to this baseline. However, three fundamental shortcomings in existing research limit their applicability to China’s building decarbonization pathways planning:
(1) The binary classification framework (residential vs non-residential buildings) inadequately captures China’s complex building energy landscape characterized by socioeconomic heterogeneity (rural–urban dichotomy), regional disparities (five climate zones), and diversified energy portfolios (different heating systems in southern and northern regions). This methodological oversight may lead to suboptimal prioritization of cost–effective carbon abatement technologies. A case in point is China’s urban–rural divergence, wherein electrification remains the highest-priority decarbonization lever for rural residential buildings, whereas urban residential buildings with relatively high electrification rates may require more focus on energy efficiency.
(2) Simplified demand-side assumptions and using carbon emission reductions to evaluate potential may underestimate the effect of demand-side non-technical measures and overestimate the contribution of technical measures. From the demand side, most research on developed regions adopts almost static demand projections, in which building service demand is almost saturated and does not change significantly. This assumption is not suitable for transition economies in which building energy demand would still increase greatly with well-being improvement. Regarding the evaluation of emission reduction potentials for technology solutions, setting a high service demand could lead to results indicating huge carbon emission reduction potentials, while maintaining relatively low energy demand would dramatically reduce the potential value. However, previous studies do not pay too much attention to this phenomenon and explore the development paradigm, driving force, and effect of building service demand.
(3) Technical measures remain narrowly confined to the building itself, fundamentally overlooking the transformative mitigation potential of cross-sectoral innovations enabled by system-wide energy transitions. For instance, building–grid interoperability through vehicle-to-building (V2B) technologies and industrial waste heat recovery for building space heating could contribute significantly to carbon emissions reduction, as mentioned above. These system-level decarbonization synergies are critical for carbon neutrality goals and should be considered in future technology perspectives.
These limitations motivated our research, which addresses these gaps as follows:
(1) A four-category approach has been adopted to characterize building energy use and emissions in China. In contrast to most building stock models that divide the building sector into residential and non-residential building energy use, this study categorized China’s building energy use into four major categories based on long-term research into the operational energy consumption of civil buildings in China [
[35],
[36],
[37],
[38]]. This categorization accounted for the differences in winter heating methods between northern and southern regions, the disparities in building forms and lifestyles between urban and rural areas, as well as variations in occupant behaviors and energy-using equipment between residential and non-residential buildings. The four categories were as follows:
• orthern urban heating (NUH) energy use: This category included the energy use of various provinces, autonomous regions, and municipalities, and included all urban areas in northern China that use district heating methods during winter.
• Urban residential (UR) building energy use excluding NUH: This category included residential building energy use in urban areas, excluding the NUH. It included energy use for household appliances, air conditioners, lighting, cooking, domestic hot water, and winter heating in provinces, autonomous regions, and municipalities, where it is hot in the summer and cold in the winter.
• Rural residential (RR) building energy use: This category included the energy consumed by rural households, encompassing cooking, heating, temperature drop, lighting, domestic hot water, and household appliances.
•Public and commercial (P&C) buildings excluding NUH: This category accounted for the energy used by buildings for public and commercial purposes, including offices, commercial buildings, tourism buildings, buildings for educational purposes, buildings for communication, and buildings for transportation in urban and rural areas.
These differences can lead to significant differences in the energy efficiency and emission reduction technology paths adopted by the four building energy use subcomponents. This classification methodology has been widely recognized by policymakers, researchers, and engineers in China’s building energy field, incorporated into the national standard [
39,
40], and extensively cited and acknowledged by international energy researchers [
41].
(2) A comprehensive analysis of China’s building energy demand development paradigm was conducted, and the carbon neutrality pathways planning was conducted following our proposed concept of ecological civilization development. Specifically, we prioritized demand-side measures by defining total final energy use and intensity as primary targets, rather than emphasizing energy efficiency improvements, energy savings ratios, or emissions reduction ratios. Likewise, in planning the carbon-neutral pathway, we began by setting periodic energy and carbon emissions targets to better synergize with China’s dual carbon policy needs. Then, we established phased priorities and technology promotion objectives that consider both the technological maturity and development stage of the building sector.
(3) Cross-sectoral technological synergies were systematically evaluated and planned from a whole-system decarbonization perspective. Specifically, this study established an integrated analysis model, namely the China building energy and emission model (CBEEM), to capture the trend of energy and emissions in the Chinese building sector. Then, three distinct narratives were set to explore the building energy demand growth under different development paradigms, which were the intensive, moderate, and ecological modes. Finally, a detailed pathway for the ecological development mode was planned to outline the technological roadmap for the transition process of China’s building sector toward the carbon neutrality goal.
The remainder of this paper is organized as follows. Section 2 outlines the categories of building energy consumption and emissions in China and describes the modeling methodology and scenario settings used in the study. Section 3 provides a comprehensive analysis of the modeling results and presents the scenario results for different emission trajectories. Section 4 provides insights and conclusions, including key technological advancements and policy implications for attaining zero-emission pathways.
2. Methodology
The lifecycle of a building encompasses several stages, including ① building material production, ② building material transportation, ③ on-site building construction, ④ building operation, ⑤ retrofitting and maintenance, and ⑥ demolition and material recycling [
3,
4]. Moreover, according to the Intergovernmental Panel on Climate Change (IPCC) [
42], building-related carbon emissions are categorized into three types: ① direct carbon emissions from building operations (Stage ④), which refer to emissions from the direct combustion of fuels such as coal and natural gas within buildings; ② indirect carbon emissions from building operations (Stage ④), which refer to the carbon emissions caused by electricity and heat consumption for building operations; and ③ embodied carbon emissions from building construction, which refer to energy and emissions during stages ①, ②, ③, ⑤, and ⑥.
According to our previous studies, China’s embodied carbon emissions from buildings reached 1.5 billion tonnes of CO
2 (tCO
2) in 2022 [
43], primarily driven by the carbon emissions from the production of construction materials such as steel and cement, which account for over 80% of the total. Under China’s policy framework, these emissions are classified under the industrial sector’s carbon peaking and carbon neutrality efforts [
44]. Previous studies by the Building Energy Research Center (BERC) of Tsinghua University have analyzed the historical trends [
13] and future scenarios [
12] of the building construction-related embodied carbon emissions. The building sector also has non-CO
2 emissions caused by refrigerant leakage [
45]. We analyzed the fluorinated gas (F-gas) emissions from China’s building sector [
45], specifically from room air-conditioners [
46]. Therefore, in this study targeting achieving carbon neutrality in China’s building sector, we focused solely on operational CO
2 emissions from buildings in China.
The present study is grounded in the extant CBEEM modeling platform and concentrates on the ensuing aspects to facilitate scenario analysis and path planning for the realization of China’s building sector carbon neutrality target, illustrated in
Fig. 1. First, the output data of CBEEM was updated from 2020 to 2022 and calibrated, thus reflecting the recent trend and status of China’s building energy use and emissions. Moreover, this study utilized a novel methodology to compare global building energy use and carbon emissions to exclude structural and efficiency differences in the supply side, focusing on discrepancies in the building demand side. This enabled a better understanding of building energy demand growth patterns and thus identified China’s future path. Second, this study used the CBEEM model to conduct scenario analyses of future energy demands for buildings in China, and combined it with aggregate results derived from models for the whole society and other sectors to analyze the feasibility of different demand growth scenarios for buildings. Finally, this study implemented ecological development pathway planning with the CBEEM model. The pathways are designed to mitigate energy demand increase with sufficiency measures first, followed by measures to enhance energy efficiency and the use of renewable energy sources to reduce energy consumption and carbon emissions.
2.1. The China building energy and emission model
In this study, we collected all the data sources required for the model based mainly on the CBEEM platform developed by BERC, updated the model output to 2022, and also calibrated the model results to ensure that the results were harmonized with the energy and carbon emission data of various sectors in China. BERC began researching China’s building energy consumption data from 2005 and developed the first version of the China building energy model to track and analyze China’s building operational energy use data [
47,
48]. Building upon the China building energy model, we expanded its output from energy to carbon emissions, incorporated a module for building construction energy consumption and carbon emissions, and added a module for non-CO
2 greenhouse gases in buildings. Additionally, we enriched the data sources and optimized the model validation methods, ultimately developing the CBEEM, to analyze the trajectory of energy consumption and emissions associated with buildings in China, and to highlight advancements in key sectors and emerging technologies related to building energy efficiency and emission reduction.
The CBEEM integrates two core components: the China building construction energy model and China building operation energy model. It is driven by key input data modules, which include demographic, household, building stock, appliance ownership, technology penetration rate, efficiency, and climatic data. The outputs from the China building construction energy model and China building operation energy model are subsequently fed into GHG emission models to estimate carbon and F-gas emissions, as depicted in
Fig. 1. Notably, the heat consumed in northern urban heating systems is considered as building energy consumption, and accounted for by the primary energy (natural gas or coal) used by the heat source.
Compared with similar models, the CBEEM uniquely integrates bottom–up data from multiple sources by diverse end-users and climates, and validates outputs through top–down comparisons with national energy balances and sectoral models. This integration ensures that the CBEEM’s results align with national and sectoral totals, enabling China’s building sector to effectively coordinate its pathway toward national low-carbon transitions.
Second, the CBEEM explicitly captures variations in building energy use intensity (EUI) arising from occupant behaviors coupled with technology selections across climate zones and building typologies. For example, public buildings in China demonstrate two distinct EUI profiles: small-to-medium-sized buildings with decentralized HVAC systems generally exhibit lower EUI, while large-scale complexes with centralized HVAC systems typically show significantly higher EUIs [
12,
43,
44]. In residential buildings, the impact of occupant behaviors is even more pronounced, causing EUI differences ranging from three to tenfold depending on space heating/cooling system types and occupant usage patterns [
[46],
[47],
[48]]. These patterns were quantitatively reflected in the CBEEM model during historical analysis and future scenario settings. More detailed descriptions of the CBEEM and its underlying data sources can be found in a previous study [
11].
2.2. Comparison of global building energy use and emissions
A comparative analysis of building energy consumption and carbon emissions across different countries, along with an examination of their underlying causes, is essential for understanding China’s current status. Due to differences in fuel types (electricity, heat, coal, and natural gas) and the substantial variations in national energy supply structures, no unified conversion method for calculating building energy use currently exists. This issue leads to significant inconsistencies and affects technology adoption and policymaking.
The two commonly used methods are the final energy method and the primary energy method. The final energy method (also known as the electrical and thermal equivalence method) converts all energy types based on equivalent calorific values, thus ignoring conversion losses [
49,
50]. This simplification can result in misleading comparisons such as directly equating 1 kW·h of electricity with 1 kW·h of heat. The primary energy method adopted by China (coal equivalent method for electricity) aggregates all energy at the primary level [
51]. However, the growth of renewable electricity complicates appropriate primary-energy conversion factors. Considering this study’s focus on building energy demand, we proposed an electricity equivalence method, converting all energy sources into electricity based on global average power generation efficiencies. Using global mean efficiency rates derived from our previous study [
52], we adopted conversion factors of 3.21 kW·h per kilogram of coal equivalent (kW·h·kgce
−1), 4.09 kW·h per kilogram of oil equivalent (kW·h·kgoe
−1), 4.74 kW·h per normal cubic meter of gas (kW·h·Nm
−3), 133 kW·h·GJ
−1 (boiler heat), and 70 kW·h·GJ
−1 (CHP heat). Building energy use data was collected from the IEA database [
50], and population and income data were obtained from the World Bank (WB) database [
53]. The equivalent electricity consumption calculated with this method allowed comparisons of building energy demand and carbon emissions without the confounding effects of national energy structures or conversion efficiencies.
We comparatively analyzed total building operational carbon emissions, per capita energy use, and carbon emission factors per unit of electricity consumption. By analyzing these metrics and digging deeper into the reasons for discrepancies, we aimed to identify different development patterns of building energy demand and their key drivers, so as to rationally plan and navigate the future direction of China’s building sector.
2.3. Future scenario analyses and pathway design
In this study, the carbon neutrality goal for China’s building sector was set to zero-carbon emissions without considering carbon capture and storage (CCS) or carbon sinks. Therefore, the priority for achieving zero emissions was to completely eliminate direct fossil fuel emissions, a no-regret strategy. Based on this, the end-use energy types in buildings must be carbon-free electricity and heating. Therefore, future scenario analyses were conducted individually for heat and electricity demand from other building types and end-users and analyzed using the CBEEM platform (
Fig. 1).
For heating demand in northern urban areas, two main pathways were analyzed and compared: ① full electrification through heat pumps powered by zero-carbon electricity, and ② utilization of waste heat resources to replace coal and natural gas.
For electricity demand (excluding northern urban heating), three development scenarios toward carbon neutrality were considered: an intensive scenario (matching current US levels), a moderate scenario (similar to European standards), and an ecological scenario (slightly above current Chinese demand). Guided by the sufficiency principle and targeting per-capita floor-area levels comparable to those of Europe and developed Asia countries, we set development goals for the per-capita floor area of each building type. Applying the China building stock turn-over model, we then calculated the annual trajectories of China’s building floor area. The total building floor area in China was projected to increase to 75.0 billion m
2, including 37.8 billion m
2 of urban residential buildings (90 m
2·household
−1), 16.2 billion m
2 of rural residential buildings (143 m
2·household
−1), and 21.0 billion m
2 of public and commercial buildings (15.5 m
2·capita
−1). Annual carbon emission factors for electricity were set as a boundary condition based on zero-carbon transition scenarios from the Chinese Academy of Engineering’s research on the strategies and paths for carbon peak and carbon neutrality, detailed setting could be found in Fig. S1 in Appendix A [
54] . Subsequently, one feasible scenario was selected, and an in-depth pathway design was conducted based on this narrative, outlining key technologies, their implementation processes, and the required policy mechanisms.
3. Results and analyses
3.1. China’s building energy and emissions
In this research, we updated the input driving parameters of the CBEEM model to obtain the latest data on China’s building energy use and emissions, and calibrated our results. According to our estimation based on CBEEM, over the past two decades, China’s total building stock has more than doubled, with an annual growth rate of 3.8%. Recently, construction activity has gradually stabilized, maintaining an annual new construction area of approximately 3.4 billion m
2 and demolition area of approximately 1.4 billion m
2, indicating a trend toward slower growth post-2020. By 2022, China’s total building stock reached 69.6 billion m
2, including 31.8 billion m
2 of urban residential buildings, 22.4 billion m
2 of rural residential buildings, and 15.4 billion m
2 of public and commercial buildings (
Fig. 2(a)). Consequently, the per capita residential floor area reached 38 m
2, while public and commercial floor area was 11 m
2.
In 2022, China’s total operational building energy use reached 1.17 billion tonnes of coal equivalent (tce), accounting for 21% of the total energy consumption in China. This included 2.3 PW·h of electricity, and 0.4 billion tce of fossil fuels (coal and natural gas). Further, another 0.05 billion tce of non-commercialized biomass was consumed in rural China during that year. From 2000 to 2021, China’s building EUI grew 2.2-fold, while carbon emission intensity increased by only 1.3-fold. This disparity reflects the mitigating effects of increased electrification and energy decarbonization in China’s building sector, offsetting increasing emissions from rising demand. In 2022, the total carbon emissions from building operations in China were 2.2 billion tCO
2, accounting for 21% of China’s energy-related carbon emissions. This study then analyzed the characteristics from two dimensions. First, we analyzed the direct and indirect emissions according to the IPCC classification (
Fig. 2(b)). Then, we adopted a four-classification approach considering the specificity of building energy consumption in China (
Fig. 2(c))
The proportions of direct carbon emissions, indirect carbon emissions from electricity use, and indirect carbon emissions from heating in China’s building sector were 21%, 58%, and 21%, respectively (
Fig. 2(b)). The direct carbon emissions of buildings were 450 million tCO
2, encompassing urban and rural cooking (approximately 150 million tCO
2), household gas- and coal-fired heating boilers (approximately 210 million tCO
2), and natural gas consumption for hot water, steam boilers, and absorption refrigeration (90 million tCO
2). Rural areas were the largest emitters, accounting for more than 50% of the total direct carbon emissions. These emissions have declined steadily since peaking around 2015, driven by policies promoting clean heating, coal substitution, and electrification in rural areas. Electricity consumption by building operations in China was 2.3 PW·h, resulting in 1.26 billion tCO
2 of indirect carbon emissions. Electricity accounted for 65% of the total energy use in urban residential buildings and public and commercial buildings. Moreover, the share of electricity gradually increased with the progress in electrification. Despite reductions in electricity emission factors (541 gCO
2·(kW·h)
−1 in 2022), rapid growth in electricity demand caused overall indirect emissions from electricity to continue rising. Indirect emissions from heating, primarily district heating in northern urban regions, accounted for 440 million tCO
2 and have peaked in recent years.
Fig. 2(c) illustrates the floor area (
X-axis), carbon emission intensity (
Y-axis), and total carbon emission (size of square) of the four sub-sectors. The P&C buildings sub-sector has the highest electricity intensity (83 kW·h·m
−2) and carbon intensity (47.4 kgCO
2·m
−2). With the steady increase in the stock and EUI, the total amount of carbon emissions from P&C is still rising and becoming the largest component. Following P&C buildings sub-sector is NUH, covering northern urban residential and commercial buildings, which has a carbon intensity of 29.3 kgCO
2·m
−2. Its emissions have already peaked, stabilized by improved heating efficiency and cleaner energy sources. Residential buildings have a larger floor area but lower carbon intensities. Due to coal substitution policies in rural areas (coal-to-electricity and coal-to-gas), emissions from rural residential buildings have peaked and begun declining. Conversely, carbon emissions from urban residential buildings continue rising with urbanization and improved living standards.
3.2. Global comparative analysis
To analyze trends in China’s building energy demand and emissions, we conducted a global comparative and historical trajectory analysis, focusing on demand-side differences while excluding energy supply variations.
Fig. 3(a) presents the historical evolution (2000–2021) of building carbon emissions across select countries. The
x-axis represents building EUI (kW·h electricity equivalent per capita), the
y-axis shows carbon emission intensity (tCO
2·capita
−1), and sphere size denotes total building emissions per country. By 2021, China had surpassed the US as the largest global building sector emitter, though its EUI remained far lower than in developed countries—about one-fifth of the US and Canada, and one-third of Sweden. Developed countries, having reached saturation in building services, focus on energy efficiency and renewable energy, reducing emission intensities (e.g., the US from 8.0 to 5.4 tCO
2·capita
−1 and Canada from 4.6 to 3.2 tCO
2·capita
−1). Sweden and France, benefiting from high shares of zero-carbon power, maintain lower per capita carbon intensities than China despite higher energy use. In contrast, China and India continue to rise sharply in both EUI and emissions, driven by growing building service demand. Unlike developing countries, which must balance improving building environments with energy and carbon goals, developed nations have reached service saturation. Their mitigation strategies now focus on energy efficiency and renewable adoption. In contrast, China and India continue rapid growth in both, highlighting the urgency of managing building energy demand in developing economies. This highlights the significant uncertainty in building energy demand growth in developing countries. Guiding building service levels and implementing demand-side sufficiency measures are crucial to preventing dramatic EUI increases, as in developed countries. These efforts are essential for easing the energy and carbon reduction burden in developing economies while ensuring national energy security.
Analyzing global building energy demand against per capita GDP over the long term (
Fig. 3(b)) highlights a clear pattern: with economic growth, building energy use in developed countries initially increased sharply but eventually stabilized (6000–8000 kW·h·capita
−1 in Europe; 6000–8000 kW·h·capita
−1 in Japan; and 10 000–14 000 kW·h·capita
−1 in the US and Canada). In contrast, developing countries are facing a dual challenge—meeting rising demands for improved building services and living standards, while simultaneously achieving stringent energy and carbon emission targets. This tension underscores the critical need for strategic, sustainable management of energy demand growth in developing regions.
The historical growth of building energy use and carbon emissions across various countries highlights how differing civilizational development models exert distinct economic, social, and environmental impacts. Under industrial civilization, nature is continually exploited to meet ever-increasing human demands, with built environments treated as standardized, mechanized products. Historically, building energy and emission trajectories in developed countries have followed an industrial civilization paradigm, priortizing increased energy efficiency while continuously expanding building services. The building indoor environment served as an industrial product; that is, to specify a quantitative building indoor service standard and use it as a binding indicator (as primary/hard constraint), and then to reduce energy demand as much as possible through energy efficiency measures (as secondary/soft constraint) (
Fig. 4(a)). Under this development philosophy, the end result is an unlimited increase in the required service volume and a simultaneous increase in energy efficiency and energy consumption [
55]. However, the increase in service volume does not imply an increase in satisfaction with the indoor environment and an improvement in the comfort of the occupants. This phenomenon is often referred to as the rebound effect and has been extensively studied in economic and engineering literature, underscoring the limitations of pursuing efficiency alone [
56,
57]. Dependent on fossil fuels and driven by intensive capital investment, this model has led to global crises, including environmental pollution, ecological degradation, and resource depletion, ultimately rendering the traditional industrial paradigm unsustainable and necessitating a shift toward a sustainable framework grounded in ecological civilization [
58,
59].
As planetary boundaries have become increasingly evident, demand-side measures, particularly sufficiency, have been emphasized by the IPCC’s Sixth Assessment Report as essential for climate mitigation in the building sector [
42]. This concept aligns closely with the ecological civilization development paradigm, where sustainable development occurs strictly within ecological limits [
60,
61]. China’s concept of “ecological civilization” places human–nature harmony at its core, exemplified by the principle that “lucid waters and lush mountains are invaluable assets” [
61]. This philosophy aims to strike a dynamic balance among economic development, social equity, and environmental protection, while emphasizing social justice and lasting well-being [
58,
59,
62]. In this view, buildings serve as spaces for harmonious coexistence between humans and nature, integrating indoor and outdoor environments through thoughtful design and prudent use of natural resources [
63]. Crucially, these efforts remain constrained by the upper limits of environmental capacity, reinforcing a more holistic and sustainable approach to building and urban development [
64,
65]. Under this paradigm (
Fig. 4(b)), building total energy demand and EUI are set as a primary/hard constraint, while building service amounts are set as secondary/soft constraints [
66]. This approach prioritizes sufficiency measures, nature-based solutions (e.g., natural lighting and ventilation), and defines comfort in broader, flexible ranges rather than precise, fixed standards. Empirical studies show that it is precisely this philosophy of creating the built environment (fully enclosed and mechanically controlled vs nature-based and mechanically supported), the type and operation of energy systems (centralized controlled system vs decentralized system with flexible terminals), and lifestyle and occupant behavior (full-time–full-space vs part-time–part-space) that cause differences in the building EUI between countries to vary by several-fold or orders of magnitude [
67].
Under different development paradigms (industrial vs ecological), building energy policies differ significantly (
Table 1). Under the industrial paradigm, building service levels are fixed boundary conditions, and policy emphasizes efficiency through prescriptive standards and incentives targeting adoption of high-efficiency technologies, typically benefiting higher-income groups. In contrast, the ecological paradigm prioritizes sufficiency first, followed by efficiency improvements. Incentives here encourage both technology adoption (higher-income groups) and reward behavioral changes, which could guarantee justice transition and provide subsidies to alleviate energy poverty (lower-income groups). However, due to late-stage development and resource constraints, developing countries such as China cannot replicate the building development patterns of developed nations. The ecological footprint of developed countries, such as the US, indicates unsustainable resource consumption. According to previous research on ecological footprint, we would need 5.1 Earths if everyone lived like Americans [
36]. Therefore, proactively adopting an ecological civilization approach is essential for China and could provide valuable lessons for developing regions.
This study follows the ecological development paradigm, which sets building energy demand targets by considering China’s energy resource endowment and carbon emission constraint targets. In the CBEEM, we tracked the behavior diversity across climate zones, building types, and technology systems. In scenario analyses, we set building energy demand targets by integrating top–down energy supply constraints with bottom–up assessments of achievable sufficiency and efficiency improvements. This dual approach ensures energy demand scenarios remain realistic and aligned with ecological limits. Future pathway planning further emphasizes this ecological approach, guiding sustainable transitions in China’s building sector.
3.3. Future scenarios analysis
Phasing out fossil fuel combustion is China’s choice and a global consensus toward achieving the carbon neutrality goal of China’s building sector. Due to China’s coal-dominated energy structure, the transition from coal to gas has been promoted as a major policy cluster to achieve a low-carbon and clean energy transition. For instance, since 2017, the “coal-to-gas” and “clean heating” policies in northern China have effectively reduced both air pollutants and carbon emissions. However, in the long term, natural gas still produces carbon emissions, and phasing out its use in buildings will be an inevitable choice. A number of countries, including the US [
68], Canada [
69], some European countries [
70], and the UK [
71], are accelerating the implementation of national, state, and city bans on heating systems with natural gas. On the other hand, although hydrogen utilization in buildings is under discussion, the safety risks associated with blending hydrogen into gas pipelines have not been addressed. Additionally, natural gas is currently the primary source of hydrogen production, accounting for around three-quarters of the annual global dedicated hydrogen production [
72]. Therefore, hydrogen use in buildings is excluded from this study, leaving electricity and heat as the only energy sources.
3.3.1. Heating demand scenarios
The NUH constitutes the largest thermal demand in the Chinese building sector, primarily served by a centralized district heating network. Currently, the thermal demand is primarily met by CHP units fueled by coal and natural gas. Other regions with lower space heat intensities and no centralized networks (e.g., hot summer and cold winter climate zones and rural areas) should rely on electric-driven heat pumps, so the estimations are attributed to electricity demand scenarios. These heating demand scenarios only cover the NUH.
In the business-as-usual (BAU) scenario, maintaining the 2022 heating intensity with the NUH building stock increasing to 22 billion m
2 would raise total heating demand to 7.4 billion GJ (
Fig. 5). In an efficiency-improvement scenario (energy retrofits, stringent efficiency codes, and optimized system regulation), heating intensity could be reduced to 0.25 GJ∙m
−2, lowering total demand by 27% (to 5.4 billion GJ). Approximately 6 billion m
2 of older buildings (pre-2000 construction) [
38] with poor envelope performance require renovations at a rate of 100–150 million m
2 annually to meet this target.
Transitioning entirely to electric heating would demand an additional 0.7–2.0 PW·h of electricity, nearly doubling China’s current building electricity consumption. This would not only necessitate significant investments in end-user equipment and power capacity, but also exacerbate the power shortage in the winter. Leveraging existing district heating networks to utilize abundant waste heat resources offers a more cost–effective path to zero-carbon heating. China’s future waste heat availability is estimated at 22.9 billion GJ annually [
73], including nuclear power (7.0 billion GJ), thermal power plants (7.0 billion GJ), industry (5.0 billion GJ), and other heat sources (3.9 billion GJ). Notably, aside from buildings, industries in China (primarily non-process industries such as food processing, textiles, and chemicals) also have heat demands. Recovering 70% of this waste heat could fulfill the NUH and industrial low-temperature heat demands. However, this requires developing a comprehensive waste-heat-sharing infrastructure (seasonal thermal storage, efficient long-distance transport, and heat-grade conversion) to overcome temporal, spatial, and parameter mismatches. Detailed pathway planning is discussed in Section 3.4.5.
3.3.2. Electricity demand scenarios
Assuming that all building end-uses, excluding NUH, are electrified, three scenarios were analyzed (
Fig. 6).
• Intensive scenario: Following US building usage patterns, electricity intensity reaches ∼8500 kW·h·capita
−1 (13 000 kW·h·household
−1 for residential buildings and 200 kW·h·m
−2 for public buildings), peaking at 12.0 PW·h, which is clearly unsustainable relative to China’s estimated total future electricity capacity (16.0–18.0 PW·h). According to estimates by the Chinese Academy of Engineering, the total electricity consumption of society is expected to reach 16.0–18.0 PW·h by 2060 [
74,
75]. In this intensive development scenario, buildings could consume between two-thirds and three-quarters of the total electricity usage of society, highlighting its unsustainability.
• Moderate scenario: Following European Union building usage patterns, electricity intensity is ∼4500 kW·h·capita−1 (6000 kW·h·household−1 for residential buildings and 130 kW·h·m−2 for public and commercial buildings), totaling ∼6.2 PW·h. This would double the current demand, aligning with developed country averages. The total building electricity demand (6.1–6.3 PW·h) would exceed 6.0 PW·h, representing a nearly two-fold increase over the current level. In this scenario, the energy consumption of buildings accounted for approximately one-third of the total electricity usage in society, which aligned with the current average ratio observed in developed countries.
• Ecological scenario: Here, the narrative was to maintain the current lifestyle and building usage patterns in China while leveraging technological innovations to achieve a modest increase in building energy intensity and a considerable improvement in building service levels. This EUI will increase to 3000 kW·h·capita−1 (4000 kW·h·household−1 for residential buildings and 90 kW·h·m−2 for public and commercial buildings), bringing a doubling of total growth to 4.2 PW·h.
Although building-related electricity emissions will eventually decline to zero in all scenarios due to full electrification and power sector decarbonization, the total electricity demand under different development pathways significantly affects the complexity and cost of achieving a zero-carbon power system. Exceeding China’s renewable energy resource capacity would cause electricity costs to rise nonlinearly, threatening energy security and environmental sustainability. Previous studies [
74,
76,
77] conducted by several authorities on carbon neutrality in China indicate China’s sustainable electricity demand is limited to 15.0–20.0 PW·h, of which buildings should ideally account for no more than 5.0–7.0 PW·h based on developed-country benchmarks (approximately one-third of total electricity). Therefore, applying an ecological civilization perspective, China’s building electricity demand should be capped between 4.0–5.0 PW·h. The decarbonization pathways presented below are designed within this energy and carbon constraint to achieve improved building services.
3.4. Decarbonization roadmap
The above analysis indicates that the decarbonization of the Chinese building sector cannot solely rely on zero-carbon energy supply, but must also emphasize demand-side measures within clearly defined energy limits. This approach aligns with the ecological development concept, which aims to achieve sustainable development within planetary boundaries, constrained by total energy consumption rather than focusing exclusively on efficiency. It mirrors the IPCC’s sufficiency principle as a critical strategy for climate mitigation in the building sector [
42]. Accordingly, we developed an ecological scenario outlining five key pathways to ensure China’s building sector achieves zero emissions within these energy boundaries. These measures include the following:
• Building stock sufficiency: shift focus from new construction to renovation and maintenance of existing buildings, limiting growth within sustainable resource constraints.
• Building energy sufficiency and efficiency: achieve full electrification with priority on energy sufficiency and efficiency technologies, balancing occupant comfort within defined ecological boundaries for energy use and emissions.
• Renewable electricity: installation of building distributed PVs to generate electricity and make full use of the building’s flexible load and storage resources to consume as much green electricity as possible.
• Zero-carbon heat: promote decentralized heat pumps in southern and rural China and utilize district heating networks with zero-carbon waste heat resources in northern urban areas.
Detailed implementation pathways are illustrated in
Fig. 7 and summarized in
Fig. 8, with further sector-specific strategies discussed in subsequent sections.
3.4.1. Building floor area
Managing building energy demand through rational floor area planning is critical for carbon emission reduction, influencing both embodied and operational emissions. Planning total and per capita building floor areas is essential, which ensures reasonable needs for per capita space and living welfare while also considering equality to avoid poverty issues because of insufficient living spaces. According to our estimation results from CBEEM, China’s per capita residential area (35 m2 urban and 45 m2 rural) already approaches that of developed countries (e.g., Japan, France, and Germany). However, public building space (11 m2·capita−1) remains comparatively low (∼15 m2·capita−1 in developed countries). Under an ecological scenario, targets of 40 m2·capita−1 of residential and 15.5 m2·capita−1 of public space would sufficiently support improved living standards, leading to a total building area of 75 billion m2 (37.8 billion of urban residential, 16.2 billion of rural residential, and 21.0 billion of public and commercial). Accordingly, China’s building construction should shift from rapid new development toward renovation and maintenance, similar to post-urbanization patterns in Europe, Japan, and Republic of Korea, to ensure a sustainable building sector. In this scenario, China’s annual urban residential construction should decline from 2.0 billion to 0.6 billion m2, with demolition rates decreasing from 1.5 billion to 0.5 billion m2, stabilizing at approximately 38.0 billion m2. Public and commercial building stock will saturate around 21.0 billion m2 by 2040, while rural building areas will decline to 16.0 billion m2 by 2050 due to population decreases.
3.4.2. Building energy sufficiency and efficiency
The foundation for achieving zero-carbon emission goals lies in implementing sufficient and efficient measures to minimize total energy demand. The Chinese building sector is confronted with the challenges of improving living standards and achieving the dual carbon goals. Implementing energy sufficiency and efficiency policies within the framework of ecological development is crucial to prevent substantial increases in the total amount and intensity of building energy demands [
42]. First, when creating indoor building environments, priority should be given to passive and natural solutions whenever possible. The goal of indoor environmental control should not only be to maintain a constant and unchanging environment, such as a “five constants” environment (i.e., constant temperature, humidity, oxygen levels, pressure, and fresh air), but also to allow fluctuations within a certain comfort range in response to outdoor weather changes [
78].
In addition, green lifestyles and energy-saving behaviors are important for achieving high indoor satisfaction with low energy intensity. For example, for building space heating and cooling, which accounted for the biggest share of building energy demand, a “part time and part space” mode should be adopted instead of the “full time and full space” mode [
65]. Empirical research utilizing surveys [
79,
80] and big data monitoring [
81,
82] has revealed that the typical behavior of Chinese households can be described as “part time and part space.” Therefore, the key is to maintain the current lifestyle and develop building energy systems and terminals that are compatible with this behavior, thereby achieving high energy efficiency and low energy intensity.
Based on the above efforts on behavior and sufficiency, building energy efficiency should be further strengthened. This includes promoting envelope energy efficiency in new and existing buildings and improving the efficiency and flexibility of building energy systems. With the slowdown of new building construction in China, the focus of building envelope performance improvements will shift from new to existing buildings over time. Specifically, reducing the heating demand by deep renovating existing buildings in northern urban areas is the highest priority.
In northern China, approximately 2 billion m2 of urban residential buildings were constructed prior to 1990, and another 3.3 billion m2 were constructed between 1990 and 2000. These buildings have poor envelope performances and heating demands of > 0.3 GJ·m−2. In addition, approximately 1 billion m2 of public and commercial buildings in the northern area require further deep renovation. Increasing the insulation thickness and airtightness levels can substantially reduce the heating demand (i.e., from 0.33–0.37 GJ·m−2 in 2022 to around 0.25 GJ·m−2). These are also prerequisites for achieving the zero-carbon target of the NUH.
By strategically increasing building energy consumption, it is possible to enhance building service levels and indoor environments, thereby satisfying the growing demand for a more pleasant and improved quality of life. In terms of the development approach of ecological civilization, the target for residential building electricity use intensity was set at 4,000 kW·h·household−1, and the target for public building energy intensity was set at 80 kW·h·m−2. This would enable China to double its building sector electricity consumption, reaching a total of 4 PW·h, while simultaneously achieving decent living standards and sufficient indoor building services. In addition, the total heating demand of the NUH would remain almost the same as that in 2022, with increased building stock (i.e., approximately 5.5 billion GJ).
3.4.3. Building electrification
Given the shift toward renewable-based, zero-carbon power systems, the building sector must pursue full electrification of heating, cooking, and domestic hot water production. New technologies, such as electric flame stoves, have made it possible to generate flames that enable electric cooking to better meet the flame requirements favored by traditional Chinese cooking culture. Electric heat pumps (air-, ground-, and water-source) are recommended as primary replacements for fossil-fuel boilers and direct electric heating in hot summer and cold climate zones and rural areas [
16,
83]. Recent advances have addressed several key limitations of conventional heat pump technologies, including low energy efficiency at low temperatures, frosting on the outdoor unit under high-humidity environment, and optimization of indoor unit airflow distribution and enhancement of thermal comfort. Moreover, flexible control strategies and integration renewable energy could further expand applications of heat pumps in heating supply, including space heating, domestic hot water and steam production. Additionally, air-source heat pumps can efficiently provide domestic hot water compared to direct electric heaters. However, natural source heat pumps alone cannot provide the high-density heating demand required in the NUH. This is discussed in Section 3.3.5.
Given that electrification in the building sector represents a no-regrets measure, we recommend revising building design codes to prohibit gas pipe installations in all new buildings. For example, Beijing has already banned gas heating in new buildings as part of its carbon neutrality initiatives. Meanwhile, full electrification in existing buildings should first be piloted on a smaller scale and progressively scaled up once technical solutions and implementation strategies are fully developed. To promote electrification effectively, implementation should prioritize public buildings over rural and urban residential buildings (
Fig. 8). Following this roadmap, China’s building sector can achieve near-total electrification by 2050 and fully eliminate direct carbon emissions by 2060.
3.4.4. PEDF building systems in urban areas
Achieving carbon neutrality in China requires replacing fossil-based systems with renewable electricity, primarily from wind and solar power [
84]. However, large-scale development of wind and solar power faces constraints due to limited installation space and challenges with the integration of intermittent power generation. The building sector possesses key resources to overcome these bottlenecks. First, the rooftops and surrounding spaces of urban and rural buildings in China provide space resources for installing distributed PV systems. High-resolution satellite analyses estimate China’s urban and rural rooftops can accommodate PV installations totaling 2.9 billion kW, generating 3.5 PW·h annually—roughly one-third of China’s total renewable power capacity [
85]. What’s more, by coupling with electric vehicles (EVs), buildings are able to leverage significant energy storage and regulation capabilities, thereby coordinating the grid for peak and valley regulation, as well as consuming more volatile wind and PV power [
86].
In urban buildings, the primary energy storage resource is EVs connected to the building’s power distribution system. Considering EVs as 100 units per 10 000 m2, buildings can achieve a transient charge/discharge capacity between 0 and 1 MW and a daily storage capacity exceeding 5 MW·h. Additionally, distributed electrical and thermal storage solutions (e.g., ice/water storage in public buildings, domestic hot water tanks in residences) and flexible-use appliances (e.g., washers and dryers) further enhance demand flexibility.
China’s vision of building a new type of power system is characterized by synergy between supply and demand and flexibility and intelligence. Integrating flexible building demand with renewable power through the proposed PEDF (PVs, energy storage, direct current, and flexibility) system is essential [
14]. In PEDF, “P” refers to BIPVs; “E” involves distributed energy storage within buildings and utilization of battery resources from EVs in nearby parking lots; “D” indicates the use of a direct current power supply within the building; and “F” represents the objective of achieving flexible power usage, making the building a flexible load or a virtual, flexible power source for the grid. Buildings thus become flexible electricity users, capable of balancing renewable generation fluctuations and enhancing grid stability. The construction of PEDF buildings should align with the expansion of wind and solar power (target: 7000 GW) and EV adoption (target: 7000 GW). The implementation plan involves pilot demonstrations in the first step to refine technologies and mechanisms, followed by accelerated construction; thereafter, ultimately reaching 35 billion m
2 of PEDF-equipped urban buildings (60% of the total urban stock). This capacity would facilitate an annual utilization of 3500 GW of wind and solar power, representing approximately half of China’s projected renewable capacity.
3.4.5. Low-carbon transition of the NUH
Decarbonizing indirect emissions from the NUH requires first energy efficiency improvement and demand intensity reduction. With deep renovation of building envelope systems, total NUH heat demand can remain at ∼5.5 billion GJ while the supplied building floor area will increase. As discussed before, China possesses 22.9 billion GJ of residual heat resources, including waste heat from power plants, waste incineration, nuclear power plants, data centers, and industries such as metallurgy, non-ferrous metals, chemical production, and building materials. Recovering 70% of the total residual heat could simultaneously meet the high-density heating demands of the NUH and industrial production demands [
19]. To achieve this, it is necessary to build a regional residual heat sharing system based on an existing district heating network connecting different heat sources to users. Energy storage is at the core of zero-carbon energy, and this is also true for thermal systems. Seasonal thermal storage is key to achieving a year-round balance between low-carbon waste heat supply and demand. To meet the space heating demand of the NUH and the industrial heat demand, the required total heat storage capacity should reach approximately 1.2 billion GJ. This would necessitate constructing 400–500 thermal storage facilities, each with a capacity exceeding 10 million m
3. This will require not only significant spatial resources and financial investment, but also further research and development. Such large-scale thermal storage facilities will enable the effective use of various waste heat sources, improve the heating supply capacity of the current heat sources, avoid additional peak heat sources, and enhance the safety and reliability. From an implementation timeline perspective, in the first stage, the primary task is to explore the waste heat potential of existing thermal power plants. This involves the recovery and use of waste heat from turbines and boiler flue gases to replace traditional coal boilers, gas boilers, and small-to-medium-sized CHP plants. With this technically feasible and inexpensive approach, the heat demand of additional buildings added to the network can be met without the need for new heat sources. Then in the second stage, the construction of seasonal thermal storage projects should begin in parallel with the closure of thermal power plants or a significant reduction in operating hours. By collecting waste heat from thermal plants throughout the year, the reduction in heat sources due to the shutdown of thermal power plants can be addressed. In the final stage, relying on completed large-scale seasonal thermal storage projects, it will be possible to collect year-round waste heat from nuclear power plants, peaking thermal power plants, wind and solar power curtailments, and various industrial low-grade waste heat. This will enable the NUH to be fully supplied by zero-carbon waste heat sources and achieve carbon neutrality. The step-by-step implementation plan for end users, thermal networks, and heat sources is outlined in
Fig. 8. Ultimately, creating a zero-carbon heat system in northern China requires coordination among building, industrial, and energy sectors, encompassing heat source upgrades, storage deployment, and a multi-regional heat distribution.
3.4.6. Rural PV-based energy systems
Rural areas in China have long faced issues of low indoor environmental comfort, heavy fossil fuel use, and high levels of both air pollutants and carbon emissions. Yet, its extensive rooftop areas and flexible energy demands create favorable conditions for clean energy transitions, particularly solar power, with a potential capacity twice that of total rural energy consumption. Building a new rural energy system based on rooftop PVs can fully meet rural energy requirements, including agricultural production, building services, and daily transportation, thereby displacing coal, oil, and natural gas with electricity. Moreover, PV systems can also support commercial biomass production to boost farmers’ incomes, all while reducing pollutant emissions and advancing rural revitalization.
Since 2020, China has introduced a series of policies to promote rural PV development. However, insufficient grid flexibility and limited distribution capacities in rural grids have led many regions to begin restricting distributed PV installations, or “red zones.” This is because under the current full grid-connection mode, the PV capacity (20 kW·household−1) is greater than the grid distribution capacity (less than 5 kW·household−1). This saturates or overloads the transformers in the back-end area of the PV installations in 20% of the rural households. This results in PV installations reaching at most 20% of their potential. Relying solely on passive grid upgrades to build rural PV systems is not feasible, since this approach involves high costs, long construction times, and harms the economic benefits of PVs. Therefore, new technical approaches and deployment models are urgently needed.
From a technical perspective, systems should follow a “self-consumption with surplus feed-in” principle to fully develop and utilize local energy storage and flexible electricity resources, substantially reducing the required distribution capacity. An integrated “production–storage–regulation–consumption” rooftop PV system is recommended, wherein production refers to 10–20 kW of PV installation; storage refers to more than 60 kW·h of electricity storage capacity, such as batteries of EVs (50–70 kW·h·unit−1) and electric agricultural machinery; regulation refers to storing excess power during peak solar generation and discharging it to the grid in an orderly manner and at evening or peak demand; and consumption refers to the full electrification of rural energy use and self-consumption priority to cover all energy use with PV power. Through an appropriate time-of-use feed-in tariff mechanism, it can realize the orderly connection of rural PV power generation to the grid.
From a deployment model perspective, farmers who own the rooftop should own the property rights of PV systems while enjoying the economic benefits of feeding electricity into the grid. These are crucial for motivating rural household behavior and leveraging the flexibility of rural energy use. It is recommended to implement the construction program at the village level, with local governments coordinating low-interest loans, product procurement, installation, commissioning, and training for operation and maintenance. Under this model, farmers serve as the primary investors of rooftop PV systems, while third-party agencies provide technical installation and maintenance services. The village-level microgrid should be invested in by the government to facilitate energy sharing among households and transfer surplus electricity to the grid after coordinating during peak consumption hours. Based on this framework, the combined promotion of household- and village-level systems should be implemented at the scale of individual villages or transformer substations, each encompassing approximately 100–150 households. The step-by-step implementation pathways are listed in
Fig. 8. As the ultimate goal, rural China will be fully electrified and mainly supplied by rooftop PV systems, supplying an additional 1.5 PW·h of electricity and 0.2 billion commodified biomass fuels to urban areas.
4. Discussion and policy implications
4.1. Conceptual innovations to achieve building neutrality
The transition from industrial to ecological civilization represents a fundamental shift in how humans and nature coexist. While industrial civilization relies on extensive extraction of nonrenewable resources to meet insatiable human demands, driving immense social progress since the industrial revolution, this approach also triggers ecological crises. In contrast, ecological civilization redefines the human–nature relationship to seek harmony and balance, rather than fulfilling infinite demands. This principle applies in several areas:
(1) Building stock: In terms of per capita building area, the aim should be to achieve an appropriate living area, adhering to the principle that “housing is for living, not for speculation,” rather than “the bigger, the better.”
(2) Building indoor environment: Priority should be given to integrating with the natural environment instead of maintaining constant temperature, humidity, oxygen, pressure, and fresh air (“five constants”). Mechanical solutions should intervene only when environmental parameters deviate substantially from comfort ranges. Moreover, environmental control should target occupied spaces and specific times, rather than all spaces continuously.
(3) Building energy system: In low-carbon energy systems driven by renewable electricity, buildings should shift from rigid to flexible power loads. This entails adjusting indoor conditions (e.g., temperature setpoints and ventilation rates) to match real-time supply and demand, rather than aiming to continuously fixed loads. In other words, building services should no longer aim to maximize the immediate and fixed demands of users, but allow for a certain range of demand fluctuation. Such flexibility allows building energy systems to strike a dynamic balance between user comfort and carbon reduction.
Furthermore, achieving a low-carbon transition in the electricity and heating sectors requires deep coupling and coordinated transformation of buildings with other sectors:
(1) Building transport synergy: Establishing a new power system necessitates simultaneous upgrades of buildings and EVs. Their distribution systems and operational modes should be unified to optimize storage, demand response, and flexible electricity use. Comprehensive planning, construction, management, and operation of charging infrastructure and building distribution networks can enhance security and responsiveness. Incentive mechanisms are also needed to reward demand responsiveness among buildings, as demonstrated by pilot PEDF projects [
87].
(2) Building–industry synergy: Creating a zero-carbon heating system requires accelerating infrastructure to collect, regulate, store, and distribute waste heat. Such large-scale projects demand significant investment and coordination across regions and institutions, including network planning and site selection for thermal storage. National-level oversight should guide these phases. Mechanisms to monitor, calculate, and assess different heat grades will also promote effective waste heat recovery and use.
4.2. Policy and financial support for transformation
Innovative policy mechanisms must be established to align with the proposed roadmap and ensure the timely completion of scheduled targets.
First, scientific carbon accounting and clarity on the economic benefits of reduced emissions are urgently needed. This entails improving methods to quantitatively manage building emissions, including setting accounting boundaries, establishing standards for emissions from power generation and different heat grades, and creating data management systems for monitoring, reporting, and public disclosure. Subsequently, low-carbon and zero-carbon building evaluation standards should be established based on actual emissions, and market-based mechanisms (pricing scheme, reward) should be introduced to incentivize real emission reduction efforts.
Second, high-level policy design (e.g., national action plans) is vital for advancing emerging technologies. Formulating comprehensive technical roadmaps and policy frameworks for new power systems and low-carbon heat systems in both urban and rural areas is strongly recommended. Core infrastructure for zero-carbon electricity and heat should be incorporated into China’s new infrastructure planning initiative, ensuring strategic coordination.
Third, further research and development is essential, particularly for PEDF buildings, rural energy systems, and low-carbon heating. It is also crucial to strengthen regulatory tools, such as building design codes, to promote electrification, set higher goals, and improve efficiency, sufficiency, and flexibility. Additionally, information campaigns should educate the public on the benefits of low-carbon energy technologies and behaviors.
Finally, financing for low-carbon infrastructure is paramount, with over 22 trillion CNY needed for PEDF buildings, smart charging networks, rural PV deployment, and low-carbon heating solutions (Table S1 in Appendix A). Under integrated planning, public infrastructure (e.g., heat networks, rural microgrids) should be jointly funded by government subsidies and local utilities, while building owners and rural residents would invest in distributed PVs and charging facilities.
Green financing instruments and low-interest loans can help front these costs; returns are then recouped from emission reductions, energy savings, and electricity sales. With adequate pricing mechanisms for carbon, electricity, and heat, investors can expect payback periods of 10–20 years. This further emphasizes the critical role of carbon emissions accounting and trading, along with energy use accounting and trading mechanisms, in optimizing the economic benefits of energy infrastructure projects and promoting financial investment in these areas. Further analyses on key challenges across categories are in Table S2 in Appendix A.
5. Conclusions
China, the world’s largest developing country and second-largest economy, faces the dual challenge of enhancing building services while curbing energy use and carbon emissions—an issue also confronting many developing nations. Utilizing the integrated CBEEM model, we analyzed the current energy consumption and emission status in China’s building sector and highlighted the critical challenges and opportunities. Through a global comparison, this study innovatively proposed the concept of ecological development pathway, in contrast to the industrial civilization development pathway, to address the conflict between improving human well-being and environmental protection. This concept was further applied to the pathway planning for achieving carbon neutrality of China’s building sector. The main conclusions and findings obtained from this study are as follows.
According to CBEEM’s estimation results, in 2022, China’s building operations account for 21% of its primary energy consumption and 21% of its energy-related carbon emissions. In 2022, total building emissions reached 2.2 billion tCO2, reflecting extensive urbanization, increasing building areas, higher living standards, greater use of electricity, and progressive improvements in energy efficiency. While direct emissions and indirect emissions from heat have peaked, overall building emissions continue to rise due to the steady growth of electricity-driven emissions. The decline in electricity carbon emission factors due to the low-carbon transition of the power system has not offset the increased electricity demand due to electrification and rising living standards.
Many developed countries have all experienced a significant increase in building EUI alongside economic growth. In comparison, China’s EUI remains notably lower, driven by different lifestyles and usage patterns. The ecological pathway emphasizes demand-side strategies and nature-based measures, coupled with proactive energy-saving behaviors that meet energy and emission targets, while maintaining adequate service levels. Under China’s current resource constraints and overall emission limits, a “sufficient demand” scenario posits 4.2 PW·h of electricity and 5.4 billion GJ of heat (for NUH). Attaining carbon neutrality requires rationally managing new construction and shifting focus toward retrofitting existing buildings, preserving moderate lifestyles and green practices to avoid skyrocketing EUI, fully electrifying buildings (apart from northern urban heating), deploying PEDF building systems in urban areas, transitioning northern heating from fossil fuels to waste heat, and building rural energy systems based on rooftop PV.
These findings underscore the importance of demand-side initiatives and leveraging new technologies for sustainable building development in alignment with climate objectives. The efforts of China in achieving decarbonization not only provide valuable lessons for demand-side growth in the building sectors of other developing countries but also offer technological pathways for transitioning to low-carbon building energy systems in other developed and developing countries with similar resource endowments. Future studies should address regional disparities in achieving peak building emissions, evaluate technology suitability across varied climates and building types, and examine cost, supply-chain, and policy factors influencing technology uptake. In addition, research on the socioeconomic impacts of such technologies will be crucial to inform equitable and effective strategies for carbon-neutral buildings worldwide.
CRediT authorship contribution statement
Shan Hu: Writing – original draft, Visualization, Software, Methodology, Formal analysis, Data curation, Conceptualization. Yi Jiang: Writing – review & editing, Project administration, Methodology, Funding acquisition, Formal analysis, Conceptualization. Xudong Yang: Writing – review & editing, Formal analysis, Conceptualization. Yungang Pan: Writing – review & editing, Resources, Conceptualization. Xiangyang Rong: Writing – review & editing, Resources. Bin Hao: Writing – review & editing, Resources, Conceptualization. Ziyi Yang: Visualization, Software, Investigation, Formal analysis. Yang Zhang: Software, Investigation. Da Yan: Writing – review & editing, Resources.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
This work was supported by the National Natural Science Foundation of China (52478095 and 72261147760), the Chinese Academy of Engineering Project “Low-Carbon Transition Strategy and Pathways for Urban and Rural Energy Supply Systems in China” (2023-XBZD-07), and the China Postdoctoral Science Foundation (GZC20240874).
Appendix A. Supplementary data
Supplementary data to this article can be found online at
https://doi.org/10.1016/j.eng.2025.07.006.
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