Liu Jiaping, academician of the Chinese Academy of Engineering: Building a low-carbon, smart and safe house

Building carbon emissions are closely related to every professional type of work in the entire construction industry chain, including urban master planning, building scheme design, structural and structural design, electromechanical equipment system design, etc., as well as various building materials production, building construction and equipment installation, indoor and outdoor decoration, supporting municipal facilities, environmental protection facilities, etc., as well as the operation and maintenance of building systems. In theory, every type of work has the potential and possibility to reduce emissions. In recent years, government authorities, planning and design companies, building materials manufacturers, technology research and development units, construction and installation companies, etc. have made efforts to promote energy-saving buildings, green buildings and low-carbon buildings, and achieved remarkable results. However, it should also be noted that after energy-saving and low-carbon building technology develops to a higher level, the potential for further reducing energy consumption and carbon emissions is gradually decreasing. The industry has always expected to be able to invent and create transformative technologies or products that can be fully promoted to achieve carbon neutrality in the construction field. But in fact, there is still a long way to go to realize these expectations.

Looking back on the past 30 years of research and promotion of building energy conservation and green buildings, it is not difficult to find that more attention has been given to the former in terms of application of building energy conservation technology and energy conservation design. Since the end of the last century, my country has introduced a variety of building energy-saving technologies such as heat pumps, photovoltaic photothermal, and high-performance doors and windows from developed countries. While improving building quality and environmental performance, it has greatly improved building energy efficiency. In terms of building energy-saving design, it is slightly inferior. Since the 1980s and 1990s, a series of national and industry design specifications such as the "Energy Saving Design Standards for Civil Buildings (Heating Residential Buildings Part) JGJ26 -95" have been issued for heating residential buildings in the north, and energy-saving technical systems such as external insulation of buildings have been implemented one by one in heating residential buildings in cold and severe cold climates, and the effect of saving heating energy is obvious. However, when solving the energy-saving design problems in climate areas such as hot summer and cold winter and hot summer and warm winter, no countermeasures suitable for the regional climate characteristics have been developed, and the energy-saving design methods for heating buildings in the north are still used for reference. Implementing external wall insulation technology in hot summer and cold winter climate zones and hot summer and warm winter climate zones where air conditioning energy consumption in summer is the main source of energy consumption, the energy-saving effect is not obvious and the building maintenance cost is increased to a certain extent.

Actively and steadily promote carbon peak and carbon neutrality, we must vigorously promote clean and low-carbon transformation in industry, construction, transportation and other fields. The report of the 20th National Congress of the Communist Party of China proposed to "coordinate the layout of rural infrastructure and public services to build a livable, business-friendly and beautiful countryside" and "implement urban renewal actions, strengthen urban infrastructure construction, and create a livable, resilient and smart city." Improving the livable quality of urban buildings and improving the quality of rural living environment will increase the consumption of energy and other resources to a certain extent and directly or indirectly increase carbon emissions. In the future, it is necessary to further clarify the connotation of green buildings and clarify the technical route to ensure that the "double carbon" goal is achieved as scheduled.

The first is to accurately understand the connotation of green building. According to the latest definition of the national standard "Green Building Evaluation Standards"(GB/T50378-2019), green building evaluation indicators include almost all building performance. From the perspective of building users, green buildings must be healthy buildings, that is, green, low-carbon, intelligent and safe "good houses"; from the perspective of sustainable social development, green buildings emphasize "four sections and one environmental protection", namely Energy conservation, land conservation, water conservation, material conservation and environmental protection. Green buildings are low-carbon buildings that reduce greenhouse gas emissions such as carbon dioxide. Comprehensive implementation of green buildings will help achieve the "double carbon" goal.

The second is to attach importance to carbon emission reduction during building operations. According to statistics from the China Building Energy Conservation Association, carbon emissions from the building materials production stage accounted for 28% of the country's total carbon emissions in 2020, which is higher than the proportion of carbon emissions in the building operation stage, but will decrease as the construction volume declines. Since the production of carbon dioxide is a chemical process, building construction and operation will not directly emit carbon dioxide. However, from the perspective of the entire life cycle of the building, energy consumption and carbon emissions during the operation stage will always exist, and their proportion will increase with the increase in building volume., the improvement of the quality of the building environment will increase year by year.

The third is to focus on energy conservation and carbon reduction on reducing energy consumption for heating, air conditioning and lighting. On the one hand, calculated based on unit area and unit time, the energy consumption and carbon emission intensity of building heating, air conditioning and lighting are very small. Taking heating houses in the north as an example, the annual operating energy consumption per square meter is less than 10 kilograms of standard coal, and the carbon emissions are around 20 kilograms, but the total energy consumption and carbon emissions of more than 65 billion square meters of buildings across the country are large. On the other hand, the energy consumption and carbon emissions of building heating, air conditioning and lighting are closely related to the building shape, indoor space organization and envelope structure construction methods, that is, they are closely related to the creation of architectural plans and construction drawing design. Excellent building plan design can achieve zero energy consumption and zero carbon emissions through clever use of renewable energy.

The fourth is to focus on improving architects 'ability to create and design green building plans. It is recommended to carry out basic research on green building design, evolve the quantitative performance indicators in the green building evaluation standards into design calculation parameters one by one, and green the content of various types of building design standards, specifications and design manuals and architectural teaching materials to ensure that architects can Create green building plans and design blueprints.

The author is an academician of the Chinese Academy of Engineering and director of the National Key Laboratory of Green Building