Grid-interactive high-efficiency buildings are a crucial pathway to achieving carbon neutrality in high-density cities.

“Grid-interactive high-efficiency buildings are a crucial pathway to achieving carbon neutrality in high-density cities.。” When meeting with reporters, Cheng Yu, deputy chief engineer of Shanghai Tongji Engineering Consulting Co., Ltd. and director of the Green and Low-Carbon Research Center, put forward the above views directly.

Reporter: Can you introduce the background of this view?

Cheng Yu:The "dual carbon" goals and carbon neutrality are essentially an energy transformation for the entire society, replacing fossil fuels with large-scale renewable energy to address climate change and achieve the goals of sustainable human development.

Data shows that in 2023, China's installed capacity of renewable energy accounted for about 50% of the total installed capacity nationwide. However, in the same year, the power generation of non-hydro renewable energy (mainly wind and solar energy) only accounted for about 16% of China's total electricity consumption. (Figure 1, Note: Sources include the National Energy Administration, etc., data from different statistical methods may vary slightly). Coal-based fossil fuel power generation accounted for 61%. In 2023, the global share of non-hydro renewable energy was about 13%, and coal-based fossil fuel power generation accounted for 61%, still dominating, which is the "difficulty of renewable energy consumption".Currently, fossil fuel power generation still dominates. Both the power grid and the building sectors should increase efforts to improve the consumption ratio of renewable energy.。

Figure 1

 

 

Reporter: What are the practical difficulties in increasing the consumption of new energy,

and how to solve it?

Cheng Yu：In modern power systems, the supply side and the demand side are two important concepts. They have different focuses in technology, policy, and management, and sometimes even contradict each other.Electricity, as a special bulk commodity, is transmitted to users through the power grid at near light speed.Modern power grids are high-tech equipment and complex systems that ensure electricity transmission. In this system, the power grid is usually only responsible for areas outside the red line (supply side), while users are responsible for areas inside the red line (demand side). The power grid needs to ensure high safety, while users require convenient electricity experience. At the same time, the volatility of renewable energy often poses a challenge to the stability of the power grid, which is an important aspect of the supply-demand contradiction.

Considering the energy consumption characteristics of modern cities: According to the World Cities Report 2024, global urban areas only account for 3% of the land area, but accommodate 56% of the population, contribute more than 80% of GDP, and produce more than 70% of carbon emissions. Currently, China's urbanization rate exceeds 66%. In the southeastern coastal areas of China, such as the Bohai Rim, the Yangtze River Delta, and the Guangdong-Hong Kong-Macao Greater Bay Area, the high-density population and industrial agglomeration have led to the characteristics of "high-density energy consumption" in these cities. At the same time, due to insufficient local power generation, they need to import electricity from inland areas, exhibiting the characteristics of "energy import cities".

The difficulties in renewable energy consumption mainly lie in two aspects:First, the contribution of photovoltaic power generation in high-density cities to the building's own energy consumption is relatively low, so a large amount of electricity still relies on external grid supply; second, for safety reasons, the power grid is difficult to accept renewable energy in a concentrated and large-scale manner. The building sector believes that using "light" plus "storage" can solve the problem of zero-carbon building energy, but the difference between expectation and reality is very large:

The "installed capacity" of building photovoltaic (including BIPV and BAPV) is not equal to the "power generation". In addition to meteorological factors, the orientation and shading of urban buildings are also major factors affecting power generation. In high-density development (especially high-rise high-density) cities, the total building area per unit land area is higher, and the roof utilization coefficient is relatively small, the possibility of exterior wall utilization increases but shading is also strengthened, and the utilization rate decreases. It has been estimated that, assuming sufficient photovoltaic installation, in a "near-zero energy consumption" building scenario in a city with a plot ratio of 3.0, about 55% of the energy consumption within the building red line needs to be accessed from the city's power grid.

The material basis of chemical energy storage is limited. There are videos on the internet mentioning that the global battery production in five years is "only enough for Tokyo to use for 3 days." This statement is theoretically valid. However, building energy storage still has broad prospects, including hot water storage, air conditioning chilled water storage, digital load storage, and building photovoltaic power generation resources. According to data from the International Energy Agency and other institutions, in building energy consumption, lighting accounts for about 10%-20%, air conditioning accounts for 40%-60%, hot water accounts for 10%-15%, and other power accounts for 10%-20% (see Figure 2).

 

Figure 2

 

The "load" and "source" of buildings have isomorphic properties, meaning that the energy consumption demand and energy supply system of buildings have a certain matching relationship in terms of time and space, complementing and coordinating each other. By optimizing the building's energy management, building energy efficiency can be improved, and the effective use of renewable energy can be promoted.

The ideal way is "load as storage". Through demand response (DR) and flexible load management, a large number of distributed structures, flexible scheduling, and energy storage combined microgrids are realized. Microgrids can ensure a high proportion of green electricity consumption locally (within the red line) without compromising grid safety and reliability. Virtual Power Plant (VPP) technology is a comprehensive application that can optimize energy supply and demand balance by flexibly scheduling and coordinating the power generation and load of multiple microgrid units without increasing additional installed capacity, participating in the price interaction of the electricity market.

Aiming at the "dual carbon" vision, the power energy sector has proposed a new power system goal framework of "safe and efficient, clean and low-carbon, flexible and flexible, and intelligent integration." In this system, urban residents and industries have a large number of controllable loads, such as building photovoltaics, air conditioners, electric vehicles, hot water, and energy storage batteries. These resources are no longer simply "consumers," but "prosumers" that both consume and produce electricity.Therefore, the building sector needs to take the perspective of an active participant in the new power system and develop "grid-interactive high-efficiency buildings"。

 

 

Reporter: What is the technical route of "grid-interactive high-efficiency buildings"?

Cheng Yu“Grid-Interactive Efficient Buildings (GEB)” is also translated as "interactive efficient buildings." As an emerging building energy management concept, it has received widespread attention and practice in the United States, Europe (Germany, Netherlands, United Kingdom), Canada, Australia, Japan, and other places. Its technical routes mainly include:

First, building electrificationCancel the use of primary energy sources such as natural gas (similar to electric vehicles) with zero local operating carbon emissions, purchase electricity from the grid, and minimize electricity consumption while improving electricity efficiency.

Second, building power generationWhere conditions allow, install solar photovoltaic power generation as much as possible to achieve a certain level of renewable energy supply, and prioritize local consumption or energy storage to offset the amount of electricity purchased from the external power grid.

Third, digital and intelligent energy managementAfter new energy sources join the electricity market, they need to meet measurement indicators such as "measurable, reportable, and verifiable" (MRV) to ensure their traceability and transparency. At the same time, due to the volatility and intermittency of new energy sources, solving the complex interaction problem between "source" and "load" requires intelligent means. Digital technology is not only the basis for optimizing energy management and improving energy efficiency but also a key support for promoting carbon offsetting and carbon trading. The United Nations and its relevant agencies have emphasized in multiple reports that digital technologies, artificial intelligence (AI), and big data technologies have enormous potential to improve energy efficiency, reduce carbon emissions, and promote sustainable development.

Fourth, flexible interaction between buildings and the power gridThrough the collaborative work of smart grids and smart buildings, prioritize the consumption of renewable energy, peak shaving and valley filling, and reduce the power grid's carbon emission factor. "Flexibility" reflects the flexibility of the power grid; the new power system pursues not stability but dynamic balance; "interaction" is reflected in the building's empowerment of the power grid, improving energy utilization efficiency while promoting the development of green and low-carbon energy and promoting power decarbonization.

In summary, it hashigh efficiency, interconnection, intelligence, and flexibilitycharacteristics. (See Figure 3, Note: Reference data from the US Department of Energy)

Figure 3

 

 

Reporter: That sounds good. Can you introduce some practical cases?

Cheng Yu: In recent years, we have been cooperating with advanced domestic institutions in this field, and we are full of expectations for the future of the technology.。

For example, we cooperated with professors from Wuhan University. They used their independently developed "power-type intelligent controller" to assign IP Addresses to all power-consuming equipment, realizing the power Internet of Things, strong-current intelligence, and industrial AI artificial intelligence active optimization, showing a high proportion of energy saving and carbon reduction in practice. A typical case is the technological transformation of Wuhan University's intelligent energy management system. By transforming the controller to build an Internet of Things energy management and control system, improving power safety, and achieving more than 50% energy saving year-on-year (confirmed by the Wuhan University Logistics Group), intelligent flexible switching at power peak times generates a digital virtual power plant equivalent to 12 megawatts of installed capacity. In another urban renewal project, through the Internet of Things and artificial intelligence control, the efficiency of the existing hotel energy management and control system is doubled, and due to the convenience of meeting the MRV standards of digital energy management, it obtained the "Organizational Carbon Neutrality" certificate after only one year of operation through carbon trading.

In our cooperation with a smart manufacturing park in Bengbu, Anhui Province, through high-efficiency heat exchange technology combined with AI intelligent control, we achieved all-valley electric heat storage for more than 700 dormitories and management rooms, providing hot water for daily life. This achieved flexible interaction with the power grid, objectively reducing the carbon emission factor and saving a lot of operating costs for customers. (Figure 4) In addition, there are some projects in Shanghai, Shenzhen, Qinghai, etc., that are still in the early stages or in progress. These projects use advanced controllers and artificial intelligence management systems to build "grid-interactive high-efficiency buildings," and we believe they will have good results in the future.

Figure 4

 

 

Reporter: What else can you add about "grid-interactive high-efficiency buildings"?

Cheng YuIn the article "Systemic Synergistic Solutions for Building Carbon Neutrality," Academician Zhuang Weimin called for: "A large number of building scholars and engineers should consciously and consensually focus on exploring systemic solutions for new theories, new methods, and new paradigms for building design, construction, and operation oriented toward carbon neutrality." Due to my multi-dimensional experience in building design, green park development, and low-carbon consulting, I strongly agree with this initiative.

First, carbon neutrality is the energy transformation of the entire society, achieved by replacing fossil fuels with renewable energy.In the face of high-density urban environments, passive and active technologies are currently commonly used. Simply stacking them in quantity will not only fail to solve the problem but will often increase construction and maintenance costs, reduce applicability, and hinder the development of building carbon neutrality.Buildings need to "think outside the box"break through the "self" of the building industry itself, and place concepts such as green buildings, ultra-low-energy buildings, and near-zero-energy buildings in the context of "energy transformation" and "power system decarbonization." This can be done by using a large number of "grid-interactive high-efficiency buildings" to promote buildings to serve energy transformation.

Secondly, as China's financial center, Shanghai can also attract capital inflow into the low-carbon industry and promote green development through green finance and energy management business models.Combined with Shanghai's established carbon trading center, "grid-interactive high-efficiency buildings" that meet the requirements of digitalization and MRV will provide effective support for the carbon trading market and promote the pace of low-carbon energy transformation.

Finally, as a high-density energy-consuming city, Shanghai has an open spirit of "inclusiveness" and faces enormous challenges in energy transformation.It is recommended that Shanghai take the lead in piloting "grid-interactive high-efficiency buildings," combining local climatic conditions and industrial characteristics, and combining with scenarios for the urban renewal of a large number of existing buildings to explore innovative low-carbon transformation paths. This will not only provide a demonstration for the low-carbon development of the Yangtze River Delta region but will also provide valuable experience for national energy transformation.