The construction sector is the core area for energy consumption and carbon dioxide emissions, and its low-carbon transition is a key lever for China to achieve "carbon peaking and carbon neutrality" (hereinafter referred to as the "dual carbon" goals). Low-carbon buildings emphasize controlling energy consumption throughout the entire building lifecycle, mainly through reasonable planning and circular design, integrating ecological building concepts, green and environmentally friendly building materials, and advanced energy-saving technologies to achieve full-process carbon reduction throughout the building. In recent years, under the guidance of national policies, technological advances, and market demand, low-carbon buildings in China have begun to develop. The pilot scope for ultra-low energy buildings and near-zero energy buildings has continuously expanded, and related industries such as prefabricated buildings and green building materials have gradually emerged.

Energy consumption and carbon emissions in China's construction industry account for a prominent proportion. According to research by organizations such as the China Building Energy Efficiency Association, in 2022, the total energy consumption and carbon emissions of the construction industry accounted for about 45% and 48% of the national total, respectively. From a development trend perspective, from 2005 to 2022, the national total energy consumption throughout the building process rose from 950 million tons of standard coal to 2.42 billion tons of standard coal, with carbon emissions rising from 2.23 billion tons of carbon dioxide to 5.12 billion tons of carbon dioxide. It is worth noting that although carbon emissions in the construction industry are on the rise, the growth rate of carbon emissions is slowing down. Taking the building materials production stage as an example, carbon emissions are generally on an upward trend, but during the 13th Five-Year Plan period, the annual growth rate was slow. Among them, steel and cement account for more than 90% of the carbon emissions from building materials production. During the construction phase of the construction industry, the growth rate of carbon emissions also slowed down, and the total growth space was limited. Although carbon emissions continue to increase during the operational phase, the overall carbon emission factor dropped from 2.3 tons of CO2/ton standard coal in 2005 to 1.94 tons in 2022. ^[1-3]

China's per capita carbon emissions and carbon emissions per unit area of building operations are lower than those of most developed ^{countries [4]}, and large-scale incremental urban construction has basically ended, entering a stable development stage that balances quality improvement of existing assets and structural adjustment of incremental areas, with urban renewal becoming a key development focus. Meanwhile, the core requirements of urban renewal for low-carbon construction, green building materials, and energy-saving retrofits of existing buildings are also driving the construction sector toward low-carbon carbon emissions, accelerating the pace of green transformation in the construction industry.

In recent years, China's attention to green and low-carbon buildings has continued to rise. The development of low-carbon buildings has gradually shifted from single buildings to concentrated contiguous areas, from traditional construction to prefabricated buildings, and from the north to the south. Building energy conservation initiatives are gradually extending from new buildings to energy-saving retrofits of existing ones, and are progressively advancing toward large-scale implementation based on the accumulated pilot experience. At the same time, the low-carbon building-related industrial chain is taking shape rapidly, attracting more market players to participate; A batch of low-carbon new technologies has been implemented, and the proportion of ultra-low and near-zero energy buildings continues to rise. However, the development of low-carbon buildings in China still faces many practical challenges and has yet to form a large-scale, high-quality development pattern. From an industry perspective, there are still a large number of non-energy-efficient buildings among the existing buildings nationwide. Old buildings suffer from poor envelope structures and outdated energy supply equipment, resulting in high energy consumption; New low-carbon buildings generally face the problem of high technical application costs. Overall, the development of low-carbon buildings faces prominent issues such as lagging mechanisms, high costs, and insufficient technology promotion. Moreover, project investment costs are high and payback cycles are long, and the implementation and promotion of distributed energy face multiple obstacles. However, existing related research mostly focuses on a single dimension, sometimes emphasizing technological applications or policy analysis, with insufficient systematic review of the current development status of low-carbon buildings and insufficient in-depth analysis of the root causes of development bottlenecks. Against this backdrop, systematically reviewing the current development status of low-carbon buildings in China, accurately identifying bottlenecks and deep-rooted causes during development, and proposing scientific, feasible, and industry-specific development suggestions have become urgent issues to be solved for low-carbon transformation in the construction sector.

Low-carbon transformation in urban buildings is a core link in low-carbon governance and a key measure for energy conservation and emission reduction. Its development results directly affect the progress of implementing the "dual carbon" goals, thus attracting sustained and widespread attention from academia. Existing research mainly covers three categories: low-carbon technologies, carbon emission assessments of low-carbon buildings, and development pathways for low-carbon buildings. These studies support each other and jointly promote the development of urban low-carbon building theory and practice ^[5].

Low-carbon technology is the core support for achieving carbon reduction in urban construction. Current research on technology mainly focuses on two core directions: the application of low-carbon technologies from a full lifecycle perspective and the empowerment of cutting-edge digital technologies.

Carbon reduction technologies covering the entire lifecycle of building design and operation, their low-carbon technologies have attracted academic attention and have produced systematic research results. At the design and structural level, scholars explore emission reduction paths focusing on low-carbon building design logic and enclosure structure optimization ^[6-7]; On the energy supply side, automatic control technology for HVAC systems has become a research hotspot, providing technical support for improving building energy efficiency ^[8]; At the operational level, research on low-carbon strategies based on full lifecycle management theory has increased, with some studies using specific projects as case studies to verify the carbon reduction effectiveness of technical optimization during the operation ^{phase [9].} At the same time, improvements in technologies such as carbon emission factor identification and carbon reduction calculation provide quantitative support for the implementation of full lifecycle technologies ^[10-11]. This part of the study also involves two branches: green building materials and clean energy. In terms of green building material emission reduction, the focus is mainly on carbon emissions from cement, steel, glass, and other building materials, with an emphasis on optimizing carbon reduction technologies in the production ^{process [12]} and the research and application of alternative raw materials ^[13-14], providing a feasible path for low-carbon building materials. Research on clean heating technology provides differentiated solutions for low-carbon heating in different regions ^[15].

With the rapid development of digital technology, the integration of cutting-edge technologies such as digital twins, artificial intelligence, and machine learning with low-carbon buildings has become a new research trend. Some scholars have designed green and low-carbon building management platforms based on digital twin technology to achieve precise control of building energy consumption and carbon emissions ^[16]; Artificial intelligence technology is widely applied in the evolution and game analysis of the construction supply chain, providing scientific decision-making support for the low-carbon transformation of the construction supply ^{chain [17]}; Machine learning models are applied to the technical, economic, and environmental impact prediction of mid-rise office building enclosure renovation schemes, enhancing the scientific validity of the renovation plan ^[18]. The integration and application of these cutting-edge digital technologies comprehensively promote the transformation of low-carbon buildings from traditional "passive emission reduction" models to precise and intelligent "precise emission reduction" models, providing a brand-new technological path for low-carbon governance of urban buildings.

Carbon emission assessment for low-carbon buildings mainly includes two main types: setting indicator systems and full lifecycle accounting. In terms of constructing indicator systems, academia has implemented multidimensional indicator systems to achieve scientific carbon emission assessment: Zhu Wenxiang et al^{. [19]} established a three-level evaluation indicator system to provide a framework for identifying and evaluating low-carbon building features; Long Weiding et al^{. [20]} proposed "per capita carbon emission indicators" and "carbon reduction efficiency indicators," enriching the evaluation dimensions for low-carbon buildings; The mathematical model constructed by Zhang Taoxin et al^{. [21}] can effectively estimate the current status of urban building carbon emissions; Wang Cheng^[22] sorted out the similarities and differences between the evaluation systems for green and low-carbon buildings, pointed out the current issues of "high popularity but low effectiveness," and proposed optimization suggestions such as unified goal orientation to promote the improvement of the evaluation system. In terms of full lifecycle accounting, scholars have used this method to conduct multi-dimensional, multi-scenario research: Chen Lin et al^{. [23]} confirmed that building activities account for more than one-third of global energy consumption, highlighting the importance of building emission reduction; Some studies have calculated the carbon footprint of building materials such as concrete and rebar, finding that high-rise office buildings have the highest carbon intensity ^[24]; Sun Heng et al. [25] took specific engineering projects as research subjects, proposing carbon emission optimization paths and practical recommendations from the dual perspectives of carbon reduction and carbon replacement. In addition, academia actively uses new technologies to optimize carbon emission assessment methods, enhancing the accuracy and foresight of assessments: Ding Chao et al^{. [26]} constructed a quantitative carbon emission analysis model for ultra-high-performance concrete (UHPC), verifying that the steel-UHPC bridge panel scheme has better carbon reduction effects; Tang Xiaoling et al^{. [27]} used the PSO-LSTM network model to predict peak building carbon emissions, enhancing the foresight of assessment.

Currently, academia has conducted carbon emission estimation at multiple levels, including industry, region, and project. At the industry level, some studies point out that under the baseline scenario, China's construction sector will peak carbon emissions between 6.98 million tons and 7.69 million tons by 2035, requiring the achievement of the "dual carbon" goals under technological breakthroughs ^[28]; At the regional level, existing studies have used system dynamics models to analyze the evolution trends of carbon emissions in residential buildings in ^{Chongqing [29]} and predict the changes in carbon emissions during the operation phase of urban and rural buildings in Shaanxi ^[30]; At the project level, related studies have confirmed that low-carbon renovation of old public buildings has significant carbon reduction effects, and clearly define the production, construction, and demolition stages of building materials as key stages for emission reduction throughout the entire building ^{lifecycle [31].}

Based on the assessment and accounting of carbon emissions in low-carbon buildings, scholars have conducted optimization research on countermeasures for the development of low-carbon buildings. At the micro level, Wei Changqi et al^{. [32]} explored on-site consumption of building photovoltaics and integrated energy system scheduling at the community level; Diana D'Agostino et al^{. [33]} designed automated workflows to solve cost optimization challenges in building energy management, providing solutions for micro-scale low-carbon scenarios. At the macro level, researchers focus on core issues such as policy, market, and incentive mechanisms to break through. For example, Jiang Hong et al^{. [34]} pointed out that low-carbon buildings face insufficient incentives and insufficient investment, and suggested improving the carbon emission evaluation system and promoting industry structural adjustment; Zhang Shilian et al^{. [35]} pointed out that the low-carbon building market lacks multidimensional support and requires the construction of new market operation models; Chen Yajun et al^{. [36]} conducted quantitative analysis of policy texts and found issues such as overflow of environmental policy tools, imperfect full lifecycle policies, and low participation from multiple stakeholders. It is worth noting that carbon trading, as a market-based means of carbon reduction, has become a hot topic in current carbon reduction research in the construction sector. Wei Haimin et al^{. [37]} confirmed that carbon trading can influence developers and consumers through low reward and penalty costs, and that consumers are more sensitive to economic incentives and carbon trading; Wang Daiwei et al^{. [38],} in conjunction with China's carbon trading mechanism, proposed new low-carbon building concepts, evaluation systems, and market-oriented management schemes; Other studies have confirmed that carbon trading systems can promote carbon emission reductions in public buildings ^[39], providing a basis for policy optimization.

Research on low-carbon building development strategies is quite extensive. Some scholars have explored the driving factors and systematic pathways for low-carbon buildings. For example, Xu Pengpeng et al^{. [40]} believe that low-carbon legal regulation is the core driving force, while Teng Jiaying et al^{. [41]} argue that market development and environmental and ecological value are key to the sustainable development of green buildings. Some research has established systematic development paths, proposing ecological development paths covering multiple tasks such as stock management, electrification transformation, and flexible building construction for photovoltaic energy storage DC ^[42]; There is also research to derive embodied carbon limits for urban residential buildings in China from 2026 to 2060, providing quantitative standards for the five-year planning ^{phase [43].} Additionally, research has confirmed that policy incentives, policy responsiveness, and digital twin facility management functions are key to enhancing the carbon reduction capacity of green office buildings ^[44], providing empirical support for the coordination between policy design and technology implementation.

Overall, existing urban low-carbon building research has preliminarily formed an emission reduction system characterized by "technology as the core, management as the guarantee." However, existing research still has some shortcomings, such as insufficient relevance of regional differentiation studies, incomplete long-term mechanisms for multi-stakeholder collaboration, application scenarios for integrating digital technology and low-carbon buildings needing further expansion, and the suitability of policy tools and technical paths still needing optimization. In the future, the core trend for low-carbon urban construction will focus on technological empowerment and diverse collaboration. On the technical front, digital technology is expected to be deeply integrated into the entire lifecycle of low-carbon buildings, enabling real-time monitoring, precise forecasting, and intelligent regulation of carbon emissions, promoting the transformation of low-carbon buildings from "passive emission reduction" to "active emission reduction," becoming the core driving force for emission reduction; The deepening application of the full lifecycle management model enables precise full-process tracking of building carbon footprints, providing scientific evidence for emission reduction optimization; A reasonable combination of various policy tools can effectively connect the key chain of "technology R&D—policy guidance—market implementation," supporting the large-scale development of low-carbon technologies. At the entity and regional levels, it is necessary to strengthen the participation enthusiasm of non-governmental actors, while exploring more targeted low-carbon building development paths based on the resource endowments and climate conditions of different regions, promoting differentiated and high-quality development of urban low-carbon buildings.

This study differs from existing results by integrating technical analysis, policy review, international experience, and management recommendations. On one hand, the study approaches the current status and issues of low-carbon transformation in buildings from two perspectives: the pressure of the "dual carbon" goals and the demand for urban renewal, providing corresponding suggestions; On the other hand, this study accurately identifies industry issues and proposes recommendations that combine the timeliness of carbon reduction with the efficiency of urban renewal promotion, providing actionable solutions for local governments and market entities.

Figure 1: Carbon emissions throughout the building's entire lifecycle

Image source: Drawn by the author

Figure 2: Scope and content of carbon emissions in buildings

Image source: Drawn by the author

Looking at the distribution of carbon emissions throughout the entire building lifecycle, the carbon emissions from building material production, building operation, and construction stages account for approximately 55%, 43%, and 2% respectively. Energy consumption is also highly concentrated in the production and operation stages, accounting for 50% and 46% respectively. Among them, carbon emissions during the building materials production stage are mainly sourced from industries such as steel and cement; During the operation phase, direct carbon emissions account for about 19%, while indirect emissions mainly come from electricity and heat consumption, accounting for 62% and 18% ^{respectively [46].}

China's building carbon emission accounting has the following characteristics: First, the foundation for accounting is weak, with most cities having not established a complete building energy usage statistical system and lacking systematic data support; Second, there are significant differences in building energy consumption structures, with residential buildings having low energy consumption levels and heating buildings and public buildings maintaining high energy consumption; Third, the industry's development model urgently needs optimization. The phenomenon of large-scale demolition and construction of buildings has caused significant resource waste and increased carbon emissions. At the same time, there are issues such as low industrialization of construction production and short building lifespans, further exacerbating the difficulty of carbon emission control ^[47-48].

The application of low-carbon technologies is key to controlling building carbon emissions. Table 1 summarizes the main measures and key technologies currently used in planning, design, construction, operation, and management of low-carbon buildings.

Table 1 Key technologies and measures for low-carbon buildings

Countries began paying attention to low-carbon buildings as early as green buildings. The core concept of green buildings began in the 1960s, and in 1992, the United Nations Conference on Environment and Development incorporated it into the framework of sustainable development, promoting global consensus and widespread dissemination of this concept. Green buildings refer to high-quality buildings that, throughout their entire lifespan, conserve resources (energy, land, water, materials, etc.), protect the environment, and reduce pollution, providing people with healthy, practical, and efficient spaces to maximize harmonious coexistence between humans and nature ^[49].。 Although there are differences in green building evaluation standards among countries and regions, low-carbon related indicators all hold the highest weight. China started promoting the standardization of green buildings early. The Ministry of Housing and Urban-Rural Development (hereinafter referred to as "MOSR") formulated the "Green Building Assessment Standards" in 2006, issued the "Technical Rules for Green Building Evaluation (Trial)" and the "Green Building Evaluation Label Management Measures" in 2007, and in 2008 introduced measures such as the recognition of green building evaluation labels and demonstration project construction; The "Green Building Action Plan" issued in 2013 further clarified quantitative targets, requiring 1 billion square meters of new green buildings to be built during the 12th Five-Year Plan period, and for 20% of new urban buildings to meet green building standards by the end of the 12th Five-Year Plan.

After the "dual carbon" goals were proposed in 2020, policies and standards related to low-carbon buildings have been introduced intensively. In 2020, the Ministry of Housing and Urban-Rural Development, the National Development and Reform Commission, and other departments jointly issued the "Green Building Creation Action Plan," clearly setting a quantitative target for green building area to account for 70% of new urban buildings in 2022 ^[50]. In 2022, the Ministry of Housing and Urban-Rural Development issued the "14th Five-Year Plan for Building Energy Conservation and Green Building Development," proposing that by 2025, the area of energy-saving renovation of existing buildings should exceed 350 million square meters, and the scope was expanded to include rural buildings ^[51].。 In October 2021, the "Notice of the State Council on Issuing the Action Plan for Carbon Peak Before 2030" clarified the requirements and main measures for green and low-carbon development in urban and rural construction (Table 2). The "Work Plan for Accelerating Energy Conservation and Carbon Reduction in the Construction Sector," issued in March 2024, sets phased development goals for low-carbon buildings, focusing on twelve major tasks including improving the energy conservation and carbon reduction level of newly built urban buildings, advancing the renovation and upgrading of existing urban buildings, and strengthening energy-saving and carbon-reduction management in building operation, while enhancing technology research and development and policy support ^[52]. It can be said that the policy system for low-carbon transformation in buildings has already taken shape.

Table 2 Main measures and specific contents of low-carbon building policies

Source: Compiled by the author based on the content of the "Action Plan for Carbon Peak Before 2030."

In the formulation of low-carbon building standards and technical specifications, China has successively issued standards such as the "Technical Standard for Nearly Zero Energy Buildings" (GB/T 51350), "Testing and Evaluation Standard for Nearly Zero Energy Buildings" (T/CECS 740), "Technical Specification for Ultra-Low Energy Rural Housing" (T/CECS 739), as well as special technical guidance documents like the "Technical Guidelines for Application of Household Air Source Heat Pump Heating (Trial)," covering green industrial buildings, green office buildings, green rural housing, green affordable housing, green stores, Passive ultra-low energy consumption green buildings, green hospitals, green hotels, green warehouses, and various other building scenarios. Local governments are also actively carrying out practical explorations. Take Shanghai as an example: the "Shanghai Carbon Peak Implementation Plan" issued in 2022 proposed establishing a full-lifecycle energy consumption and carbon emission constraint mechanism for buildings, promoting large-scale development of ultra-low energy consumption buildings and large-scale energy-saving renovations of existing buildings; The 2023 "Shanghai 'Zero-Waste City' Construction Work Plan" further clarifies the promotion of prefabricated buildings. To ensure the implementation of related policies, Shanghai has also formulated targeted incentive measures, offering subsidies of 300 yuan per square meter to projects meeting ultra-low energy building standards.

Germany has always emphasized building energy efficiency, and its low-carbon technology system, represented by passive houses, is already quite mature and has gained widespread international recognition. A passive house refers to a type of building that does not rely on active heating equipment, but relies solely on passive technologies such as efficient insulation, solar energy utilization, and internal waste heat recovery, combined with fresh air devices with heat recovery functions, to achieve the thermal comfort requirements set by the ISO 7730 standard. The development of passive houses in Germany benefits not only from the local suitable climate but also from the continuous advancement of energy-saving technologies in buildings, the popularization of low-carbon and environmental protection concepts, and the support from economic development for industrial upgrading. Additionally, Germany leads the world in low-carbon building standards and legislation. As early as 1977, Germany issued its first building energy efficiency regulation, the "Building Insulation Regulation"; In 2020, Germany, referring to EU standards, proposed standards for heating, cooling, ventilation, hot water, and lighting in near-zero energy consumption buildings in the Building Energy Act, requiring that the energy consumption of the benchmark building must not exceed 75%; The Energy Conservation Law further requires that starting from 2021, new buildings must achieve near-zero energy consumption, and by 2050, all existing buildings must undergo near-zero energy renovations. In terms of supporting systems and incentives, Germany has established a building energy certificate system to evaluate green buildings, encourage stakeholders to independently promote energy conservation and carbon reduction, and guide social participation through voluntary evaluations, introducing voluntary sustainable building evaluation standards. Banks also provide corresponding subsidies and loans for building energy conservation. If the old house renovation project meets energy-saving standards after acceptance, a 20% reduction on low-interest loans for the renovation project can be waived. ^[53-54] In addition, in recent years, the German government has launched a series of "zero-energy buildings" demonstration projects and is supporting the exploration of zero-energy park projects, such as the EUREF-Campus in Berlin. All newly constructed buildings in the park have received green building assessment certification and are equipped with automated energy management systems. All new buildings are centrally managed and controlled through smart energy systems; The building uses energy-saving insulation materials and is equipped with an integrated facade system that can automatically adjust according to personnel activities and the natural environment; The entire construction process of the project is carbon neutral, all construction electricity comes from renewable energy, all construction equipment is energy-efficient, and the remaining carbon footprint is offset through certified carbon trading ^[55].

Japan has called 2012 the Year of Zero Energy, and since then, the government has provided financial subsidies to zero-energy buildings that meet standards, including design fees, equipment costs, and construction costs. Other measures include encouraging the use of passive building technologies, increasing the use of renewable energy, establishing zero-energy building standards, promoting full lifecycle energy management, building energy-saving labeling systems, household energy management systems, and intelligent disaster energy systems. Japan has also established supporting incentives, such as financial subsidies, loan incentives, and tax reductions. For example, in 2015, buildings with existing building energy-saving projects that reduced energy consumption by more than 15% could receive 50 million yen (about 2.23 million RMB) in subsidies, while applications of green advanced demonstration technologies could receive 50% of the subsidy ^[56].。 For low-carbon housing, the government directly exempts them from real estate registration tax and income tax. Additionally, Japan has designed a building energy efficiency labeling system that classifies energy efficiency into five levels based on the building's primary energy consumption, covering all new and existing buildings. For different types of buildings, labels such as Net Zero Energy Building, Net Zero Energy House, and Near Zero Energy Building can be affixed when requirements ^{are met[57].}。 In 2014, Japan proposed in its Fourth Basic Energy Plan to achieve zero energy consumption in newly built public buildings by 2020 and zero energy consumption in all new buildings by 2030. In 2015, Japan's Ministry of Economy, Trade and Industry established the "Zero Energy Building Roadmap Research Committee," which proposed a zero energy building roadmap based on the broad concept of zero energy. Before 2020, the promotion phase focused mainly on schools and suburban office buildings, and by 2030, it will expand to urban office buildings, commercial buildings, and more. Among these, a particularly important aspect is the use of information and communication technology facilities for energy management, such as using big data technology to improve energy utilization. The 2016 "Energy Innovation Strategy" requires all new buildings to implement mandatory energy-saving standards. In 2018, the government issued the "ZEB Design Guidelines," requiring the implementation of zero-energy buildings based on "ensuring a comfortable indoor environment" and "energy saving." Since then, Japan has continuously revised the "Building Energy Conservation Standards" in line with domestic and international development trends. In recent years, to ensure energy-saving measures for housing and buildings by 2030, Japan has increased the proportion of net-zero energy buildings and net-zero houses by improving guidance standards and building certification systems. On this basis, the Japanese government is also committed to promoting full-lifecycle decarbonized housing, enabling buildings to achieve carbon neutrality during construction, operation, and disposal. For existing housing, energy-saving renovation projects are being promoted, such as replacing glass and curtains, and partially renovating areas used daily. ^[58]

The United States is one of the earliest countries in the world to develop zero-energy buildings, achieving full coverage of zero-energy building technology systems across different climate zones, with over 800 zero-energy and near-zero-energy building projects implemented domestically ^[59].。 As early as 1990, the American Institute of Architects' Environmental Committee was established; In 1993, the U.S. Green Building Council was established. These two major organizations have led the development of green building in the United States. Among them, the Leadership in Energy and Environmental Design (LEED) certification launched by the U.S. Green Building Council has achieved widespread adoption worldwide. Key measures for low-carbon buildings in the U.S. include setting mandatory energy-saving targets, benchmarking and monitoring building energy consumption and data disclosure, building energy audits, low-carbon building retrofit programs targeting low-income groups and small and micro enterprises, providing preferential loans and other financial instruments for "Energy Efficiency Star" certified residences, implementing green building assessment and LEED certification systems, deepening the integration of business models such as public building energy-saving retrofits and energy contract management, and establishing comprehensive project tracking management mechanisms and target responsibility systems. Additionally, some U.S. states have more attention and policy measures for low-carbon buildings, with more aggressive national-level targets. Take California as an example: the state has explicitly required all newly built homes to achieve net-zero energy consumption by 2020, and to complete net-zero retrofits of 50% of existing commercial buildings by 2030, with all new commercial buildings meeting net-zero energy standards^[60]. In June 2024, the U.S. Department of Energy released the definition of "zero-emission buildings," stating that zero-carbon buildings must meet requirements for high energy efficiency, no direct greenhouse gas emissions, and all energy used in buildings coming from clean ^{energy [61].}。 Although this definition is only a voluntary guidance framework rather than a regulation, it was repealed in December 2025. Afterwards, the requirements for low-carbon buildings in the U.S. will return to being "local and market-driven," with related requirements mainly implemented through state-level energy efficiency regulations, city-level carbon emission regulations, and voluntary evaluation systems such as LEED.

The UK has long focused on a low-carbon economy, with building decarbonization levels among the world's leaders. A notable example is the Beddington Zero Energy Development Project (BedZED) in 2002. In 2006, the UK launched the Low Carbon Building Programme to fully support the development of low-carbon buildings, and later switched to a renewable energy program in 2011. The UK's laws and regulations are also very comprehensive, with the Greater London Plan 2021 being a representative example. The plan sets out three fundamental principles for planning and development projects: the Whole Life-Cycle Carbon Assessment Guidance, the Be Seen Energy Monitoring Guidance, and the Circular Economy Statement Guidance), all mainly applied in the low-carbon building sector. Among them, the "Guidelines for Carbon Assessment of the Full Lifecycle" require assessing the carbon emissions generated throughout the entire lifecycle of buildings and clarifying carbon reduction pathways. Assessment reports must be submitted at three stages: pre-application, planning application submission, and post-construction (before building handover). Unlike typical building lifecycle carbon emissions, UK buildings also focus on benefits beyond system boundaries, considering potential for reuse, restoration, and recycling. The "Visible" Energy Monitoring Guidelines specify that different responsible parties must provide visible data at appropriate stages, such as background data, building energy consumption data, renewable energy data, energy storage equipment data, equipment parameter data, and carbon emission data. To reduce waste and support circular economy policies, the UK requires major development projects to submit circular economy declarations. Based on this, the Circular Economy Declaration Guidelines are issued to clarify the specific requirements for incorporating circular economy measures into the design, construction, and operation of all development and construction projects, urging stakeholders to adopt strategies that "close" material cycles within the built environment, conserve resources, improve efficiency, design and manage sustainably, and apply circular economy concepts to the construction sector. To ensure the implementation of these principles, Greater London Plan 2021 has also specially designed a series of key performance indicators and published an annual monitoring report for public oversight ^[62].。 In September 2024, the pilot version of the UK Net Zero Carbon Building Standard was released. This document includes definitions of building types and related terms, as well as specifies assessment processes, indicator systems, and evidence submission standards, covering embodied carbon, operational energy consumption, how to avoid fossil fuels, renewable energy use, operational water use, carbon offsets, and many other areas ^[63] 。 This represents new scientific standards and guidelines for zero-carbon buildings in the UK.

The construction industry has developed rapidly with urbanization, but it is characterized by multiple industry links and long industrial chains. Compared with developed countries, China's construction industry has a relatively low level of industrialization, and precision management also faces significant challenges. Overall, the development of low-carbon buildings in China currently faces several prominent issues.

Only a few national-level low-carbon pilot cities in China, such as Shenzhen and Qingdao, have incorporated building carbon reduction into top-level urban low-carbon development designs and clarified specific carbon reduction targets. The vast majority of cities have yet to set quantitative constraints on total building energy consumption or carbon emission intensity, and the path to building carbon reduction is unclear, especially for large-scale buildings, with no mandatory controls on carbon emissions. Supporting carbon reduction policies throughout the building lifecycle still need improvement. Policies in planning and design, application of energy-saving materials, promotion of low-carbon technologies, and carbon emission monitoring lack continuity and coordination, making it difficult to form policy synergy. Currently, most low-carbon building measures are promoted through pilot programs. Successful pilot experiences often rely on local special policy support and do not follow market-oriented rules for institutional design, making nationwide promotion and replication of experience quite difficult. A particularly prominent issue is the lack and inconsistency of standards related to low-carbon buildings. For example, in energy-saving renovations, specific plans are often prepared by energy-saving service companies, but due to the lack of national or industry standards, monitoring and evaluation are mixed and mixed. Without third-party reviews, it is difficult to guarantee project quality and increases investment risks. In addition, the problem of imperfect building energy consumption statistics and data management systems is also prominent, with difficulties in obtaining building energy consumption data across regions. Finally, administrative departments related to low-carbon buildings lack coordination mechanisms, making cross-departmental and cross-entity coordination difficult. For example, the monitoring and accounting of building carbon emission data is the responsibility of the ecological environment department, the specific implementation and supervision of building energy conservation and emission reduction are led by the housing and urban-rural development department, the supply management of energy-saving building materials products falls under the responsibility of the industry and information technology department, and the supply data of water, electricity, gas, and heat are coordinated by the municipal department.

The promotion of low-carbon buildings involves multiple stakeholders, including not only the government but also owners (residents or enterprises), energy-saving service companies, third-party audit agencies, etc. (Table 3), but currently, these participants are scattered and it is difficult to form a joint force for advancement.

Table 3 Main stakeholders involved in low-carbon buildings

First, low-carbon values among residents have not yet become widespread; some wealthy individuals still tend to pursue non-low-carbon consumption models such as large apartments and frequent use of private cars; For enterprises, commercial enterprises often create low-carbon buildings with the concept of "low carbon," with the core goal of raising property prices and enhancing market competitiveness, without truly implementing full lifecycle carbon reduction requirements; Most buildings in manufacturing enterprises are factories, and their low-carbon transformation has a relatively limited impact on overall enterprise carbon emissions, resulting in low enthusiasm for enterprise promotion. At the same time, most green buildings can only meet the low-carbon targets set in the planning and design stage. Once in operation, not only is it difficult to collect carbon emission data, but there is also a lack of effective supervision and control methods, greatly reducing the effectiveness of low-carbon emissions. The root cause of these phenomena is that investing in low-carbon buildings brings short-term additional costs to residents and businesses. In the absence of mandatory constraints, most residents and businesses are reluctant to increase additional investment in the low-carbon building sector.

Secondly, relevant professionals have limited understanding of low-carbon emissions. Most architectural designers, property management practitioners, and energy-saving material suppliers have not mastered methods for integrating low-carbon concepts and technologies into their specific business operations, making it difficult to implement low-carbon requirements throughout the entire process of building design, construction, operation, and material supply. At the same time, energy-saving service companies generally have weak capabilities and face development difficulties, making it difficult to provide professional and standardized full-process services; There are few third-party agencies responsible for low-carbon building supervision, with varying professional capabilities, making scientific supervision of building carbon emissions difficult to implement. One important reason is the large fluctuations and insufficient stability of carbon prices, the immature development of the building energy conservation market, and the ineffective mechanism for market resource allocation, making it difficult to cultivate a large-scale and standardized building energy conservation industry. For example, relevant industry entities are not fully developed, lacking overall coordination and standardized guidance from industry associations; Banks and other financial institutions have not widely developed financial products such as credit and insurance suitable for low-carbon buildings, resulting in insufficient financial support and further restricting industrial development. Ultimately, a comprehensive low-carbon building market system has yet to be formed, and relevant participants lack sufficient participation capacity and enthusiasm, resulting in the value of low-carbon investment in the construction sector not being fully realized.

In addition, the perceived value bias of low-carbon buildings and insufficient market demand incentives are also major obstacles to their promotion. For example, consumers who should bear the costs related to low-carbon buildings find it difficult to intuitively perceive the long-term environmental benefits and energy-saving gains brought by low-carbon buildings. Even if they are willing to pay for related products or services, it is usually driven by the need to improve insulation performance and comfort rather than recognizing the intrinsic value of low carbon, making it difficult to effectively stimulate market demand for low-carbon buildings.

Currently, funding for low-carbon buildings is relatively limited and mainly relies on fiscal subsidies. Against the backdrop of current fiscal tightening, direct subsidies for low-carbon buildings are insufficient to support the actual funding needs for low-carbon building development. Coupled with the sluggish real estate industry, social capital participation in the low-carbon building sector is low and insufficient, further widening the funding gap.

Both new low-carbon buildings and low-carbon retrofits of existing buildings require substantial capital investment, and owners lack sufficient understanding of low-carbon energy-saving technologies. Low-carbon investments are difficult to recover in the short term and unclear long-term returns, resulting in poor promotion and application of most low-carbon technologies, and related projects also struggle to receive effective green finance support. In practice, the first to plan low-carbon buildings are mostly public buildings, with renovation funding mainly coming from fiscal funds. The proportion of self-directed emission reduction projects is relatively low, especially due to a lack of social capital participation. This is mainly because the foundation for investment gains in low-carbon buildings is weak and mature experience is lacking. Coupled with incomplete energy consumption data statistics, inadequate energy audit and consumption disclosure systems, social capital finds it difficult to predict investment risks and adopts a wait-and-see attitude. In addition, technology research and development, achievement transformation, and promotion of new low-carbon materials in low-carbon buildings all require massive funding. However, energy-saving service companies are generally small in scale and have low credit ratings. The variety of financial products related to low-carbon buildings is limited and insufficiently adaptable. Coupled with a shortage of professional financial talent in the field, these have raised the financing threshold and increased the difficulty of financing. The gap between funding supply and actual investment demand continues to widen, severely restricting the large-scale development of low-carbon buildings.

First, the boundaries of building carbon emissions have not yet been unified, and specific standards for energy consumption statistics and measurement are still in the exploratory stage. A widely recognized standard system for low-carbon building carbon emission accounting has not yet been established. For example, some building carbon accounting only covers the operational phase, while others emphasize the construction and operation phase.

Second, implementing building energy consumption monitoring is challenging, resulting in the integrity and accuracy of energy consumption data. During building operations, only the grid company's billing meters can achieve standardized energy metering; most other sectional energy consumption meters use ammeters, which is difficult to meet the precise metering needs for low-carbon building sectional energy consumption. Meanwhile, data on building heat, oil, and other types of energy lacks systematic and standardized statistics, resulting in significant data gaps.

Third, there is a lack of a unified and comprehensive system for disclosing energy consumption and energy efficiency. Although some current policy documents have preliminary requirements for disclosure of public building energy consumption and energy efficiency information, in practice, the disclosed data lacks accuracy and completeness, failing to meet the needs of carbon accounting and emission reduction assessments. Moreover, government departments have insufficient supervision over data disclosure, making it difficult to ensure the quality of disclosed data.

Finally, data related to low-carbon buildings is difficult to share. Generally speaking, data related to low-carbon buildings includes four categories: energy data included in the carbon emission statistics system, measurement data from water, electricity, gas, and heating metering instruments linked to bills by energy suppliers, instrument measurement data from units or energy-saving service companies during building operation, and dynamic monitoring data from administrative departments. However, data gaps among stakeholders are prominent, and various types lack effective sharing mechanisms and collaborative applications, resulting in a weak data foundation for energy saving and carbon reduction in low-carbon buildings, making it impossible to provide precise quantitative support for subsequent emission reduction target setting and path optimization.

Currently, China's urbanization is entering a new stage of high-quality development. Urban renewal serves as the core lever, deeply integrating low-carbon energy-saving concepts throughout the entire process. This not only embodies the intrinsic requirements of resource conservation and green development, but is also a key measure in the construction sector to achieve the "dual carbon" goals.

Government-led means the government formulates plans and action plans for low-carbon transformation at the macro level, along with a comprehensive institutional mechanism and policy guarantee system. Relevant measures have been gradually implemented, but some aspects are still in the pilot exploration or planning improvement stage. Specific measures include: combining urban building development plans, assessing total building energy consumption and the current status and trends of carbon emissions, and accurately identifying the "foundation" of carbon reduction in the building sector; Clearly define emission reduction targets in the building sector, ensuring targets are clear, actionable, progressive, and dynamically updated; Formulating a timeline and roadmap for the "dual carbon" goals in the construction sector; Improve laws and regulations related to building energy conservation to enhance applicability and operability, providing assurance for energy conservation in the region; Strengthen top-level design, carry out energy and low-carbon planning that fit urban characteristics and fully consider power decarbonization, and guide building carbon reduction in a classified and phased manner.

The government's main entry points should be public buildings and newly constructed ones, intensifying energy-saving and low-carbon renovations of existing buildings, and establishing supporting full-process systems, mechanisms, and control measures. For example, taking public buildings as entry points and new buildings as key control points, intensifying energy-saving and low-carbon renovations of existing buildings, and establishing supporting systems and control measures throughout the entire process. Clarify the boundaries of authority and responsibility for each department and institution in promoting building carbon reduction, with the housing and urban-rural development department leading the overall coordination, and relevant departments coordinating to form a comprehensive service and promotion system for low-carbon building development. Improve and upgrade existing policy standards, introduce relevant policies, regulations, and standards to promote low-carbon development in the construction sector; Improve regulatory mechanisms to oversee planning, design, acceptance, construction, operation, evaluation, and green labeling; Encourage banks and various financial institutions to participate and provide diversified support for enterprises and residents, including green subsidies, green funds, tax reductions, and low-interest loans, and introduce supporting implementation rules to strengthen protection. Establish a tripartite collaborative cooperation mechanism among government, enterprises, and the public, relying on the multi-faceted forces of administrative promotion, market regulation, and social participation to systematically advance the development of low-carbon buildings.

Building carbon emissions span the entire lifecycle—from planning and design, building material production, construction, operation, and disposal to demolition and disposal. It is necessary to build a comprehensive carbon monitoring, accounting, and systematic carbon reduction system covering all stages. Through intensive land use, selection of green building materials, energy system optimization, and improved energy efficiency, the deep integration of resource conservation and carbon reduction can be achieved, promoting the dual empowerment and coordinated efforts of technological innovation and management optimization.

During the planning and design phase, low-carbon concepts should be adopted as core design principles, fully considering the climate characteristics, sunlight conditions, airflow patterns of the building location, and other regional endowments, predicting the impact of carbon emissions throughout the entire lifecycle, and integrating energy-saving and carbon-reduction measures into the entire construction and operation design process to build a solid foundation for carbon reduction from the source.

During the production and selection stage of building materials, increase the promotion and application of low-energy-consumption materials such as steel and cement, enhance disclosure of carbon emissions from these products, and incorporate embedded carbon emissions into building design standards and construction evaluation systems. Although China has begun emission reduction controls in industries such as steel and cement, there is still significant room for emission reduction improvements in small components such as insulation materials and insulated windows. During the renovation of existing buildings, advanced energy-saving measures should be actively adopted and the energy use structure optimized.

During the construction phase, full-process management is strengthened with low-carbon control as the core. Competent authorities must strictly review the compliance of design plans with low-carbon building standards, clarify the responsibilities of all parties, and fully implement mandatory energy-saving standards; The construction process comprehensively applies diverse low-carbon energy-saving technologies, prioritizing passive energy-saving measures. By optimizing building layouts and maximizing the use of natural lighting and ventilation, this reduces energy-saving renovation costs while lowering energy consumption and carbon emissions during construction.

During the sales and transaction stage, establish a building low-carbon information disclosure system, requiring consumers to provide official certification documents such as nationally recognized energy consumption indicators and energy-saving measures, promote transparency of building low-carbon attributes, and guide the market toward low-carbon consumption orientation.

During the operation and usage phase, while ensuring residents' reasonable energy needs, promote household energy-saving models by guiding residents to choose energy-saving appliances and develop green energy usage habits, thereby reducing carbon emissions from building operations. During demolition and disposal, consideration should be given to the carbon dioxide emissions from the disposal and reuse of construction waste. Resource recovery and recycling can effectively reduce additional carbon losses caused by new material production and waste landfill.

Overall, the entire construction industry chain needs to improve energy efficiency levels comprehensively and encourage the adoption of ultra-low energy consumption building industry chain models.

There are three main types of low-carbon energy technologies in the building sector: decarbonization of the energy structure, improvement of energy efficiency, and demand-side management. The low-carbon energy structure is mainly achieved through large-scale application of renewable energy and electrification of building end-use energy; Energy efficiency improvements include raising standards for new buildings and procuring and using energy-saving products; Demand-side management relies on digital platforms to achieve intelligent energy control. At the same time, sourcing local materials and promoting carbon-reducing and sequestering building materials is also an important path for building carbon reduction. Nature-based carbon reduction and sequestration methods are also widely applied in low-carbon building renovations, such as rooftop greening, constructed wetland construction, and urban agricultural layout. Each region needs to leverage its own resource endowments and technological advantages to intensify the research and application of such technologies.

Strengthen government-enterprise cooperation, with a focus on supporting research and the transformation of low-carbon technologies. Build a low-carbon building technology innovation platform to promote technology from pilot to large-scale application. Promote the alignment of scientific and technological achievements with the needs of enterprises and industries, issue city-level energy-saving technology recommendation catalogs, and update them promptly. Fully leverage the market-driven mechanism, guide construction enterprises and relevant industry chain entities to carry out joint scientific research and breakthroughs, accelerate the localization and green upgrading of the entire ultra-low energy building industry chain, and continuously reduce industrial application costs. Strengthen the cultivation of professional talent, increase technical training related to the industrial chain, fill technical shortcomings and knowledge gaps among practitioners in the field of ultra-low energy buildings, and provide solid talent support for the low-carbon transformation of the industry.

Promote deep integration of building energy conservation into the carbon market, clarify the value orientation for building carbon reduction, and stimulate market participants' enthusiasm. Build an open, fair, and transparent market system centered on the low-carbon building industry chain, implement unified access standards and market supervision mechanisms, such as low-carbon market supervision mechanisms and low-carbon credit mechanisms. Improve the low-carbon green industrial chain, promote industrial upgrading in the building materials industry, implement green, low-carbon, and energy-saving materials, regulate the market, and form a complete low-carbon building industry system including low-carbon planning and design, low-carbon raw materials, low-carbon construction, low-carbon management, and low-carbon property management, thereby promoting the decisive role of the market in resource allocation. Actively adopt market-oriented approaches to improve building energy conservation and emission reduction, encourage energy-saving renovations and low-carbon transformation through market-oriented mechanisms such as energy contract management, demand-side electricity management, energy management, and government-private partnership (PPP) models, and encourage specialized management. Introduce credible third-party organizations and reward and punishment mechanisms to objectively evaluate energy consumption and efficiency audits. Encourage professional services from energy-saving service companies, helping homeowners recognize the connection between energy saving and living comfort, and encouraging them to pay for energy-saving benefits. Reduce costs through financial subsidies, tax reductions, or achieve added value through green building labels. Explore a platform-based development model for energy-saving service companies, solve the problem of small and scattered energy-saving projects, reduce risks for participants, and enhance the marketization of projects.

Against the backdrop of weakening local fiscal support capabilities, the importance of social capital participation in building energy conservation is becoming increasingly prominent. Local governments should be encouraged to break down market entry barriers through institutional innovation, attract more financial and social capital into the building energy-saving service market, and broaden funding channels. Innovate the green financial product system and improve supporting institutional guarantees to strengthen finance's support for low-carbon construction: First, promote the standardized development of future revenue rights pledge financing services for contract energy management, improve the valuation and realization mechanisms for income rights, and solve bottlenecks of difficult and expensive financing for contract energy management projects; Second, strengthen market supervision of energy contract management, standardize project operation processes, improve the financial support and supporting system, and ensure the safety of financial capital; Third, optimize low-carbon building credit services, formulate green project credit guidelines and supporting implementation details, providing clear standards and references for bank lending and enterprise financing; Fourth, establish a green guarantee fund, flexibly adopt diversified models such as loan issuance, equity investment, and fund investment to provide risk mitigation and protection for financial projects supporting low-carbon construction such as green credit and green bonds, further stimulating market capital participation vitality.

Establish and improve the monitoring and accounting system for building energy consumption and carbon emissions, providing standardized support for building carbon verification work. Clarify the statistical boundaries of building carbon accounting to ensure clear accounting scope, scientific methods, and accurate results. On one hand, it strengthens the standardization and comprehensiveness of manual data collection; On the other hand, relying on technologies such as the Internet of Things and intelligent energy monitoring instruments, multi-level building carbon emission monitoring systems have been developed to achieve full-process data collection, transmission, processing, and storage, meeting the core requirements of "monitoring, tracking, and assessment." Build a building carbon emission data management platform, establish multi-type energy data sharing mechanisms, disclose key energy consumption information in a targeted manner, improve the transparency of building energy consumption and carbon emission data, and provide authoritative raw data support for market activities such as contract energy management and energy-saving retrofits.

To ensure precise early warning and refined management of energy consumption, it is necessary to strengthen big data correlation analysis and the application of artificial intelligence technology, promote the comprehensive development and utilization of energy data, and provide scientific basis for government macro-control and enterprise operational decision-making. Based on energy and carbon emission data as the core and guided by market practical applications, a multi-dimensional linkage mechanism of "government—market—third-party institutions—energy users" is being established. Relying on data management platforms, build an energy-saving credit information network, improve the credit information collection and sharing system, and lay the foundation for comprehensive energy-saving credit evaluations.

To obtain relevant data and information, such as project information, enterprise information, and renovation plans, industry authorities need to establish corresponding databases; Establish an information sharing mechanism between departments to analyze the application scenarios of this data, such as eligible projects receiving green credit incentives; Strengthen full-process monitoring of projects, regularly disclose relevant data to third-party institutions and market entities, further enhancing data transparency and credibility. To ensure data authenticity and effectiveness, accelerate the construction of an integrated, unified, and interconnected energy information supervision platform, rely on internet technology to achieve broader multi-source data collection, specialized statistical analysis, and full-cycle tracking management, and promote the full-domain sharing and efficient utilization of energy consumption and carbon emission information.