Academician Jiang Yi: New Changes in Energy Efficiency and Low-Carbon Emission of Urban Residential Buildings

Academician Jiang Yi, a member of the Chinese Academy of Engineering and director of the Tsinghua University Building Energy Efficiency Research Center, systematically elaborated on the new changes in energy efficiency and low-carbon emission of urban residential buildings in recent years in a keynote report at the 21st Tsinghua University Building Energy Efficiency Academic Week Open Forum. Against the backdrop of energy revolution and a large proportion of renewable energy, the power system's supply-demand balance faces new challenges. The transformation of buildings from consumers to a four-in-one architecture of production, storage, consumption, and regulation, achieving comprehensive electrification, is of great significance. This requires technological innovation and system synergy to promote low-carbon transformation and help achieve the ambitious goal of carbon neutrality by 2060.

Report Manuscript

Distinguished guests, and fans who have supported this event for the past twenty-one years:

Good morning, everyone!

This year's Energy Efficiency Week theme: Energy efficiency and low-carbon emission in urban residential buildings. This is the fourth time that this theme has been adopted for the Energy Efficiency Week activities, in 2013, 2017, 2021, and this year, 2025. Domestic and international situations have changed significantly over the past two decades.

In particular, since the beginning of this year, the international situation has undergone dramatic changes. On the day of Trump's inauguration, he withdrew from the Paris Agreement, and climate change and carbon reduction suddenly became untouchable political taboos in the United States. Following this, some other countries such as Argentina also withdrew. Has the momentum of the energy revolution and low-carbon development shifted? Should we reconsider our future development direction? Should the energy revolution and low-carbon development continue? In fact, the United States is now the world's leading oil exporter and the largest producer and exporter of natural gas. Developing the oil and gas industry may have a role in revitalizing the American economy in the short term. This is why Trump attempted to change course and revive the oil and gas industry; it's the path he chose to try and revive the American economy. However, climate change is an objective reality, and energy transition is the only way for mankind to achieve sustainable energy development and fundamentally solve the long-standing problem of energy security. Fossil fuels must be replaced by renewable energy, so the energy transition is a path that human civilization must follow. What about China's energy transition? Unlike the United States, we have long relied on imports for our oil and gas, and we are the world's largest importer. For many years, our dependence on oil imports has remained above 70%, and our dependence on natural gas imports has now exceeded 40%. The turbulent international situation compels us to think about energy security. If our zero-carbon energy can meet our own needs and completely eliminate our dependence on imported oil and gas, our energy security level can be greatly improved. We can then confidently build our country, develop our economy, provide a better life for our people, and better fulfill our internationalist obligations.

From the perspective of the development of human civilization, the energy revolution, with its goal of energy structure transformation, will certainly be completed within this century. What is the key to achieving energy transition? Zero-carbon power sources: wind and solar power equipment; energy storage facilities: chemical energy storage, batteries; Applications: electric vehicles, heat pumps. These happen to be developing rapidly in China. Currently, China's main technologies in these areas are at the world's leading level, and its production capacity and output are far ahead of the world. If the international situation eases, these products will soon become China's main export products. Therefore, unlike the United States, which relies on oil and gas exports to revitalize its economy, exporting new energy equipment and supporting the global energy transition will become one of our main economic growth points in the future. This is also in line with the interests of people worldwide and the direction of the development of human civilization.

Therefore, China will raise the banner of mitigating climate change and accelerating the zero-carbon energy transition. The energy transition is a rare historical opportunity for us. For more than 200 years since the Industrial Revolution, China has lagged behind, been bullied, and suffered grievances. The Chinese nation yearns for rejuvenation and strength. To catch up by following the path taken by the West will be a long road. But the energy revolution can enable us to leap into a leading position during the transformation process, thereby realizing our dream of a modern and powerful nation. This may be national destiny, but it also depends on the hardworking and innovative Chinese people, on the central government's precise and scientific strategic decisions, and on the joint efforts of the whole country. Now, everything is in place, and the time is ripe. We need to exert our efforts on this front!

Residential buildings are one of the important battlegrounds for energy transition. The roofs and surrounding open spaces of urban residential buildings are important resources for the development of solar photovoltaic power generation. The increasing number of electric private cars in residential parking lots are important energy storage resources relied upon by the construction of new power systems, while the increasing number of various electric appliances in residential buildings can become flexible power consumption appliances that can participate in peak power regulation. How can we fully tap and mobilize these resources, so that buildings, while providing living space for mankind, also have the functions of "energy production," "energy storage," and "energy regulation," and combined with energy saving, Production, Storage, Consumption, Regulation "four-in-one" will be the new mission bestowed upon buildings by the new zero-carbon energy system.

In addition, cooking, domestic hot water preparation, and decentralized wall-hung boiler heating in residential buildings use a large amount of natural gas. Natural gas is a fossil fuel, and its combustion also emits carbon dioxide. Moreover, it itself is a greenhouse gas, and non-combustion leaks have an even greater impact on climate change. Comprehensive electrification, canceling the gas supply of residential buildings, and realizing Gas-to-Electricity Conversion Although there is still much debate, in the long run, it is another task that residential buildings must accomplish.

"Production, Storage, Consumption, Regulation", "Gas-to-Electricity Conversion" Difficult to achieve in a single residential building, and also difficult to implement for a single building. Rooftop photovoltaics, "one-pile-per-car" in parking lots, and comprehensive "gas-to-electricity" conversions should be implemented for residential communities as a whole. China's urban residential buildings, after years of changes and adjustments, have basically formed a model based on residential communities as the basic unit. The level of cultural construction, facility construction, and operation management in the community largely determines the living experience of residents. When material conditions basically meet the needs of residents, the living environment, cultural life, and convenience of facilities will largely determine the happiness of residents' lives. To this end, the Ministry of Housing and Urban-Rural Development proposes to build "good houses," "good communities," and "good neighborhoods" to meet people's pursuit of a better life. The "construction" here no longer simply refers to improving the construction level and quality of hardware, but more importantly, innovating and developing more suitable management models and operational mechanisms, truly operating and upgrading the residential communities we have built in cities over the past two decades to adapt to the needs of energy transformation and to provide residents with a comfortable and convenient environment, a civilized and upward atmosphere, and age-friendly and child-friendly services, so that residents can truly feel happiness in both material and spiritual life. This requires innovation in community management systems, transforming them into basic units for organizing urban residents and restoring residents' "sense of belonging". Thirty years ago, Chinese urban residents mainly depended on their workplaces, with "shops in front and factories in the back." After moving into commercial residential communities, they were separated from their workplaces. Where is the residents' sense of belonging? What is the residents' organizational model? Residential communities are the basic framework for organizing urban residents and should also be the source of residents' "sense of belonging." Community cultural life, elderly care and childcare, and resident organization and safety during special periods, such as wartime, natural disasters, and disease outbreaks, will all depend on the community. Therefore, residential communities should be the basic unit of urban residents' organizational structure. After solving the problems of food and clothing, and basic necessities of life, happiness will largely depend on the construction and management of the community. The services and management that the community provides; the software and hardware services it offers, will largely determine daily happiness and security during wartime and emergencies. Currently, the hardware systems of communities, including electricity, heating, gas, water supply, drainage, parking, garbage, landscaping, cleaning, and security, are operated and managed separately by community property management companies or professional companies, resulting in a lack of coordination and overall direction. This not only leads to frequent coordination problems between professionals but is also unsuitable for future needs such as the installation, management, and distribution of photovoltaic systems, the installation, control, and maintenance of charging piles. The inability to find suitable ways to promote the construction of these new facilities makes the organizational management model the biggest challenge in promoting the construction of new energy facilities. At the same time, many commercial houses built in the early stages of housing reform are now due for major repairs and functional upgrades. How to effectively promote the repair and renovation of buildings, such as adding elevators, replacing exterior windows, and energy-saving renovations, is gradually revealing problems in the community management system and mechanisms. The reform of the metering and charging methods for heating in northern residential buildings has also plagued us for many years. If the residential community is taken as the basic unit, the community can obtain heat from the urban district heating network, as well as from various heat pumps and even gas boilers. This can break monopolies, and through market competition, different sources of heat can be obtained at different times, allowing different communities to adopt different charging and metering methods according to residents' wishes. Fiscal subsidies paid by local governments for heating can be directly targeted at low-income communities, completely reversing the current wasteful approach. This can end the two-decade-long debate over heating metering and charging methods. In summary, from the perspective of energy transformation, meeting people's pursuit of a better life, and the requirements for community maintenance, equipment upgrades, and functional upgrades, all converge on a common issue: The establishment of new residential community organizational forms and operation and management models . It is not a matter of treating symptoms but rather a comprehensive solution to the above-mentioned problems through institutional and mechanism innovation.

Urban residents spend more than 70% of their time in residential communities. Through innovative mechanisms, we must comprehensively address issues such as cultural and sports services for residents, elderly care and childcare, building maintenance and renovation, the construction and operation of various hardware facilities systems, corresponding cost accounting and charging mechanisms, and the operation of community photovoltaics, parking, and garbage recycling, solving some funding issues. Through new systems, mechanisms, and management, enabling residents to live in a pleasant environment should be the most important work to meet people's pursuit of a better life.

In the more than two decades since the beginning of this century, high-speed urbanization and urban construction have been the themes of social and economic development. Now that large-scale housing and infrastructure construction has been basically completed, the central work in the field of urban construction should shift from new construction to the maintenance, renovation, operation, and management of existing buildings. From the perspective of operational management, the urban residential building issues we face have expanded from a single residential building to a residential community. Whether it's changes in management models or the installation of photovoltaics and charging piles, it must be analyzed, studied, implemented, and practiced using the community as the basic unit.

The above are our preliminary views on the problems currently facing the development of urban residential buildings, and they are also the main issues discussed at this building energy efficiency academic week. During the 5-day energy efficiency week, we have mainly discussed these issues, including the comprehensive electrification of residential communities, how residential communities provide charging facilities for electric vehicles, and changes in the heating methods and operation and management models of residential buildings in northern China. On Wednesday, we also specially invited several community management experts to discuss the solution approaches to a series of management problems faced by community management models and residential community maintenance, renovation, and functional upgrades. The "Annual Development Research Report on Building Energy Efficiency 2025" released today also lists our understanding of these issues and attempts to propose preliminary solutions. The focus of the research has shifted from new buildings to the maintenance, renovation, and management of existing buildings, and the basic unit has expanded from a single residential building to a residential community. Much of the content discussed has rarely been covered in previous series of "Building Energy Efficiency Research and Development Reports." This includes our new understanding of community hardware systems under the energy revolution and dual-carbon strategy, as well as our new views on residential community management based on years of social investigation and practice. These are still superficial understandings and require further exploration and practice. Today's conference forum has mainly invited experts and scholars related to these issues to express their views, and we hope to spark more discussions. The main purpose of this event is to raise these issues, not to provide answers. The true answers still require a lot of research, practice, trial and error, and iteration; this is a more complex and challenging issue than engineering and technical problems. We sincerely hope that all sectors of society will pay more attention to these issues, pool their wisdom and efforts, and work together to find a Chinese model for community and residential community operation and management, achieve sustainable development of communities and residential communities, and provide the basic conditions for a better life for the people.

China's modernization development has entered a new stage, and the energy revolution and dual-carbon strategy have also put forward higher requirements and new hopes for China's building energy efficiency cause. This requires our joint efforts to achieve the great goal of building a modern and powerful country, and to realize the beautiful aspiration of creating a happy and better life for the people. Let us work together!

I wish the conference a success today, and I hope that everyone enjoys the content of the conference and the beautiful spring of Tsinghua Garden.

Thank you!