The "Action Plan for Promoting Large-Scale Equipment Renewal and Trade-In of Consumer Goods" proposes advancing energy-saving renovation of existing buildings, with emphasis on exterior wall insulation, doors and windows, and heating devices. It also calls for continued renewal and renovation of aging gas and other pipelines. China has a large number of existing buildings (existing structures) with high energy consumption and large carbon emissions. Implementing energy-saving renovation of existing buildings and promoting trade-in in the building sector are important components of building energy conservation work at present and for some time to come, and are of great significance for saving energy, improving indoor thermal environments, reducing carbon emissions, and helping achieve the "dual carbon" goals.

Energy-saving renovation of existing buildings is an important lever

Existing buildings are buildings that have already been completed and are in use, including some high-energy-consumption buildings. These buildings have notable shortcomings such as high energy consumption and poor thermal comfort, and can no longer meet the requirements of sustainable economic, social, and ecological development. The energy consumption of these non-energy-efficient existing buildings is characterized by a large total volume, low energy efficiency, and heavy pollution.

Energy-saving renovation of existing buildings, especially public buildings, is an important way to reduce carbon emissions in the building sector and an important means to alleviate energy shortages and improve energy efficiency. According to statistics, existing public buildings consume 38% of all energy consumed in the civil building sector each year. Large existing public buildings, due to their large stock and high energy intensity, have long been an important area for energy conservation work, but also an area where progress has been relatively slow. If breakthroughs in institutional mechanisms cannot be achieved, the unreasonable increase in building energy consumption caused by the low energy efficiency of existing public buildings will not only affect the realization of the national carbon emission and carbon peak goals, but will also cause enormous waste of social resources.

Therefore, under the severe situation of tight resources and energy and large carbon emissions in China, energy-saving renovation of existing buildings means substantial savings of resources and energy and reduction of carbon emissions. This is both a concrete manifestation in the building sector of the overall national development strategy of building a "resource-saving and environment-friendly" society, and an important lever for the building sector to achieve the "dual carbon" goals.

Main contents of energy-saving renovation of existing buildings

The main contents of implementing energy-saving renovation of existing buildings include renovation of the building envelope, metering and temperature control energy-saving renovation of indoor heating systems, and renovation of heat sources and outdoor heating pipe networks.

Envelope renovation includes insulation renovation of exterior walls, exterior doors and windows, building roofs, and stairwells, with exterior wall insulation technology as the main focus.

Exterior wall insulation refers to an engineering practice in which insulation materials with low thermal conductivity (good insulation and heat-shielding effects) are fixed to building walls in a certain manner to increase the average thermal resistance of the wall, thereby achieving insulation or heat-shielding effects. Commonly used exterior wall insulation materials mainly include expanded polystyrene board (EPS board), extruded polystyrene board (XPS board), rock wool board, polyurethane foam materials, and others. Exterior wall insulation integrates insulation, waterproofing, and decorative functions, has a wide range of applications, causes little construction disturbance, and does not affect residents' normal lives. Because of these advantages, it has received widespread attention and application and plays an irreplaceable role in the energy-saving renovation of existing buildings.

Renovation of doors can reduce their heat transfer coefficient. Durable and elastic sealing strips should be installed at gaps, and high-grade insulation materials should be added inside the core panel of entrance doors, protected by panels with high strength and good sealing performance, to improve their insulation performance.

Windows are an important component of the building envelope and the most active and sensitive part of building heat exchange, generally 5 to 6 times the heat loss of walls. Therefore, energy-saving renovation of windows is a key link in the energy-saving renovation of existing buildings.

There are two ways to renovate windows: first, increase the airtightness of windows. Airtightness refers to the ability of windows to prevent air infiltration when closed. The airtightness of windows affects indoor heat loss; the better the airtightness, the less heat exchange and the smaller the impact on room temperature. Second, replace window construction materials. High-quality materials can make the energy-saving effect of windows more significant, such as replacing ordinary glass with double glazing or insulating glass. At the same time, the ordinary window frames and sash frames of existing buildings should be replaced with energy-saving materials, such as thermal-break aluminum, thermal-break steel, plastic profiles, glass fiber reinforced plastic, and composite materials.

Metering and temperature control energy-saving renovation of indoor heating systems can achieve household metering and separate adjustment of indoor temperatures. Balanced energy-saving renovation of heat sources and heating pipe networks, including the installation of metering devices and hydraulic balancing adjustment devices at heat sources, heating stations, and pipe networks, helps achieve climate compensation and variable-frequency control functions.

Carrying out heating metering and energy-saving renovation of existing buildings can effectively reduce heating energy consumption, improve living conditions and indoor thermal environment quality, and enhance the energy-saving awareness of the whole society. It is of great significance for achieving the energy conservation and emission reduction goals of the whole society and improving people's livelihoods.

Strengthen policy support for energy-saving renovation of existing buildings

Energy-saving renovation of existing buildings requires sustained, long-term efforts, because renovating a small number of individual buildings has little impact on changing emissions; only when a certain amount of accumulation is reached can the carbon reduction effect become prominent. In addition, it is necessary to combine this with the renovation of old residential communities, carry out building energy-saving and low-carbon renovation, and advance it in a coordinated manner with public environment improvement in communities, installation of elevators in multi-story buildings, and other work.

Policy support and incentives should be strengthened. It is recommended to further clarify and refine policy measures supporting energy-saving renovation of existing buildings and improve fiscal, tax, financial, investment, pricing, and other policies conducive to such renovation. Support from central funds for energy-saving renovation of existing buildings should be increased, and tax incentive policies for energy-saving renovation should be implemented. Banks and insurance institutions should be encouraged to improve green finance and other products and services to support energy-saving renovation of existing buildings.