In midsummer, the sun is like fire.
On July 16, the site of the SDIC Eco-Environment Building project in Haikou City, Hainan Province, presented a busy scene.
Installation of keels, linings, decorative strips... The construction workers are preparing for the installation of the glass curtain wall.
"Most of the building materials used in the project can be recycled and degraded, and the roof photovoltaic technology can also meet the basic electricity demand." Zhang Bing, the project manager of the general contractor of the project, introduced that through the effective use of new energy technology, SDIC Eco-Environment Building will become the "Ultra-low energy consumption" green buildings.
From the green transformation of existing buildings, to green building materials, to prefabricated buildings, in recent years, China has fully realized energy conservation in new buildings.
According to the latest data from the Ministry of Housing and Urban-Rural Development, as of the first half of 2022, the proportion of new green buildings in China has exceeded 90%.
Today, with the help of advanced technologies such as "shallow geothermal energy", China's green buildings have achieved leapfrog growth, which not only polishes the new business card of "low carbon and environmental protection", but also changes people's lives.
Concept innovation
"Soil Air Conditioning" Helps Energy Conservation and Emission Reduction
To save energy and reduce carbon, we must focus on key industries.
Data shows that the combined carbon emissions of the upstream and downstream of the national construction industry account for more than 50% of the country's total carbon emissions.
To this end, under the background of "double carbon", China's construction industry is gradually accelerating the pace of development of green buildings.
The so-called green building is a high-quality building that maintains low energy consumption, is environmentally friendly, healthy and livable throughout its life cycle.
"The reason why the time concept of the whole life cycle is highlighted is that the buildings we usually come into contact with are often already in use, but in the process of construction, there is actually a large energy loss." School of Architecture, Tsinghua University Professor Zhu Yingxin believes that if green buildings want to better achieve carbon reduction, they must first reduce the energy demand for the entire life cycle.
"For example, in terms of design, climate conditions such as natural ventilation and natural lighting can be used to adapt to local conditions, thereby reducing energy requirements for heating, cooling, lighting, etc."
Stepping into the National Cyber Security Talent and Innovation Base in Wuhan, Hubei Province, the most striking thing is the uniquely shaped exhibition center.
It is understood that the large-span column-free grid and all-glass curtain wall structure can effectively reduce lighting energy consumption.
"Everything has two sides. This unique shape also brings problems such as large heat transfer coefficient and rapid indoor temperature rise." The project designer, CITIC Architectural Design and Research Institute Co., Ltd. (hereinafter referred to as "CITIC Design") green building Tang Xiaoliang, deputy director of the research center, told reporters that in order to solve these problems, the designer team specially designed patented technologies such as "automatic control system for ventilation and heat dissipation under the condition of heat accumulation on the roof".
The reporter learned that the technology is to install 32 electric skylights in the central area of the lighting roof, and automatically adjust the opening and closing of the skylights by sensing the temperature and thermal radiation intensity of the roof area, thereby effectively controlling the roof temperature.
Tang Xiaoliang said that the computer simulation experiment found that after the optimized design, the maximum difference in room temperature is nearly 10 degrees Celsius, and the effect of energy saving and consumption reduction of air conditioners is remarkable.
At the same time, in the basement of the exhibition center, the ground source heat pump air conditioning system known as "soil air conditioning" is running quietly.
Chen Yanhua, chief engineer of CITIC Design, said that in summer, the system will transfer the waste heat in the building to the soil, maintaining a comfortable indoor temperature of 26 degrees Celsius, and in winter, the "soil air conditioner" can transfer the constant temperature underground heat to the building. Inside the building, it heats the building, forming a relatively balanced heating and cooling cycle each year, reducing direct carbon emissions by more than 35%.
"The biggest advantage of the ground source heat pump air-conditioning system is that it can use a small amount of electricity to transfer cold and heat and store it across seasons." Chen Yanhua explained that 1 kWh of electricity consumed in winter can provide 3 to 4 kWh of electricity for buildings It can provide heat, and can reduce the temperature of shallow rock and soil, and store cold energy for use in the next summer.
In addition to the design concept showing innovation, the innovative construction concept is also a major direction for the green development of the construction industry.
In the early stage of the construction of the National Convention and Exhibition Center (Tianjin) project, the project team of China Construction Eighth Bureau encountered a "hard nail".
"At that time, we initially estimated that the amount of mud discharged in the first phase of the project was close to 400,000 cubic meters, and the amount of waste mud in the second phase of the project was even more, about 460,000 cubic meters." In an interview with reporters, the project manager Li Yongfei said that in the short term Such huge mud discharge will cause great damage to the land, and at the same time, since the pile foundation construction needs to be completed within 45 days, it will take a lot of time for the mud to be transported out.
Facing the dilemma, the project technical team carried out "brainstorming".
Considering that the ground elevation in some areas of the project has not yet met the design requirements, and a large amount of earthwork needs to be backfilled, the technical team decided to try to turn "mud" into "soil" and carried out several rounds of feasibility experiments.
"But the results of the first experiment were not ideal. Due to the strong bleeding of the mud, the shrinkage ratio was very large, which did not meet the strength requirements of the backfill." Liu Fei, the chief engineer of the project, recalled that the technical team was not discouraged, but re-studied the ratio. Model selection, repeated adjustment of curing agent components, and after dozens of experiments, a suitable solution was finally successfully developed.
"The more than 800,000 cubic meters of mud generated by the first and second phases of the project are all used for site backfilling, realizing zero-emission and zero-pollution 'turning waste into treasure'."
According to the "Implementation Plan for Carbon Peaking in Urban and Rural Construction", before 2030, the level of building energy conservation and waste resource utilization will be greatly improved, and the utilization efficiency of energy resources will reach the international advanced level; the structure and mode of energy use will be more optimized, and the application of renewable energy will be more Sufficient; urban integrity, systemicity, and growth have been enhanced, and the problem of "urban disease" has been initially resolved.
Technological innovation
Build a house like "building blocks"
Not only is the building design energy-saving and low-carbon, but as the prefabricated building technology matures, the construction process of the building gradually becomes "green".
Experts point out that a prefabricated building refers to a building in which building components (such as floor slabs, wall panels, stairs, etc.) are standardized and batch produced in factories, and then transported to the construction site and assembled through reliable connections.
In simple terms, the construction method of prefabricated buildings realizes that "the house is made in the factory".
"In fact, prefabricated buildings are not available in recent years. In the 1950s, our country has begun to try to take the road of industrialization of prefabricated buildings." Cao Wanlin, a professor at the Institute of Structural and Materials Engineering, Beijing University of Technology, said that at present, China Prefabricated buildings are actively exploring standardized design, factory production and information management, which are all concrete manifestations of modern and industrialized production methods.
Recently, the first fully-assembled high-piled wharf in China designed by the China Communications Third Aviation Research Institute - No. 64-65 liquid bulk cargo berth project in Xuwei Port District, Lianyungang City, Jiangsu Province has successfully passed the acceptance inspection.
"The project makes full use of prefabricated technology, and the total number of prefabricated components is only 195. Compared with the traditional high-piled wharf, the total number of prefabricated components is reduced by more than 80%, which greatly reduces the number of hoisting of prefabricated components on the water and the amount of on-site concrete pouring." Guo Zhaojia, the person in charge, said with emotion.
Why is the wharf designed to be fully fabricated?
Hang Jianzhong, chief engineer of the project, told reporters that the project site is about 16 kilometers away from the land area behind, and the tidal range in Lianyungang area can reach 5 meters, which brings a lot of inconvenience to the traditional high-piled wharf concrete pouring on water.
In addition, according to the traditional high-piled wharf construction plan, there are many construction workers on the water, materials are piled up in a mess, and it is very difficult to organize ship traffic.
To this end, CCCC Third Aviation Institute has adopted a new type of fully assembled structure for the first time. The main components are all manufactured in factories and assembled quickly on site, and the assembly rate has been increased from 30% to more than 70%.
Because of the modular construction of the prefabricated structure, the on-site staff has also been successfully compressed from the original "thousand-person battle" to a "team tackling key problem" of more than ten people.
"Even during the peak construction period, at most 20 to 30 people are needed on site, and the working hours are relatively fixed." Guo Zhaojia told reporters that compared with the traditional high-piled wharf, the concrete consumption of the components of the prefabricated high-piled wharf has been saved by 20%. %, and the carbon emission of on-site construction is reduced by 75%.
"The prefabricated building project is like building a house like building blocks. It can reduce pollution, save resources and reduce costs while improving production efficiency." Hu Jiaxi, a senior architect at the China Academy of Building Research, said that thanks to "building blocks" With excellent quality, the on-site integration of prefabricated buildings can be carried out smoothly.
On July 18, at the Chengdu Qingbaijiang Construction Industrialized Product Production Base of China Railway Eighth Bureau Bridge Company, after completing the preparatory processes such as moulding, oiling, and tying, the workers easily operated a few buttons in just a few tens of seconds. A concrete laminate is completed.
"Our production base has adopted an 'intelligent manufacturing platform', which can produce hundreds of PC (precast concrete) components of different sizes at the same time by installing 'brains' on all production lines." Wang, Executive Deputy Director of the Construction Industrialization R&D Center of China Railway Eighth Bureau Jiang introduced that in recent years, the company has been continuously exploring intelligent manufacturing. Up to now, it has realized fully automatic processing of steel bars, automatic demoulding of products, and automatic pouring of concrete.
In addition, the "intelligent manufacturing platform" can also realize the intelligent management of the complicated production process of PC components.
After the steel skeleton of each PC component is processed, a barcode will be automatically printed by the barcode printing equipment for "identity identification".
"On-site quality inspectors can inquire about welding workers, model status and other information just by swiping with a code scanner to ensure that the steel skeleton is fully inspected." Wang Jiang said.
Zhou Jingmin, a professor at the School of Architecture and Urban Planning of Tongji University, believes that although the overall development of prefabricated buildings in China is in good shape, the next development process will still be very long.
"During the '14th Five-Year Plan' period, we should further sort out and implement standardized design thinking, so that both inside and outside the industry can correctly understand the construction method of prefabricated buildings, and gradually realize integrated coordination from the design stage."
The "Opinions on Promoting the Green Development of Urban and Rural Construction" issued by the General Office of the Central Committee of the Communist Party of China and the General Office of the State Council proposed to vigorously develop prefabricated buildings, focus on promoting the construction of steel structure prefabricated houses, continuously improve the standardization level of components, promote the formation of a complete industrial chain, and promote The coordinated development of intelligent construction and construction industrialization.
The relevant person in charge of the Standard Quota Department of the Ministry of Housing and Urban-Rural Development introduced that in the next step, the Ministry of Housing and Urban-Rural Development will build a standardized design and production system, implement the positive design method of "less specifications, more combinations", and promote the marketization of prefabricated buildings, Scale development.
city renovation
From "demolition and retention" to "retention and demolition"
Promoting the green transformation of urban and rural construction and changing the construction method of "massive construction, massive consumption, and massive emissions" are important measures to achieve carbon peaking in the field of urban and rural construction.
In terms of building a green and low-carbon city, it is necessary to optimize the urban structure and layout, and accelerate the energy-saving renovation of existing buildings.
The "Implementation Plan for Carbon Peaking in the Field of Urban and Rural Construction" proposes to strictly manage the demolition of existing buildings, and insist on promoting urban renewal from "demolition and retention" to "retention, conversion and demolition".
Walking into No. 22, Xinmin East Street, Xinghualing District, Taiyuan City, Shanxi Province, the brand-new hollow plastic-steel windows are eye-catching. After the energy-saving renovation of the building, the environment of the community has become more beautiful, the house is better to live in, and the residents' sense of happiness has skyrocketed.
"The community began to be renovated in August last year. After more than three months of construction, we moved into an energy-saving house that is warm in winter and cool in summer." 65-year-old Wang Mei is an old resident of the community. She told reporters that the energy-saving renovation solved the problem of water leakage in the house Due to the cold and other problems, the temperature in the house has increased by 5 degrees Celsius in winter.
"According to the new standard, we doubled the thickness of the thermal insulation layer of the outer wall of the community, installed hollow plastic-steel windows with better sealing properties for ordinary people's homes, and installed thermal insulation layers on the roof and basement roof." Responsible for the renovation project According to the person, through the energy-saving renovation of the building, the problems of roof leakage and loud noise along the street will be effectively solved.
No. 22 Xinmin East Street is just a microcosm of the transformation of the old community in Taiyuan.
It is understood that the first phase of the energy-saving renovation of existing residential buildings in Taiyuan has been completed in November 2021, and the second phase is expected to be completed by the end of 2023.
A few days ago, Shanxi Province issued the "14th Five-Year Plan for Building Energy Conservation, Green Building and Technology Standards in Shanxi Province", proposing that by 2025, the province will basically form a green, low-carbon, and circular construction and development mode, and new residential buildings in cities and towns will be built, Public buildings implement local standards for energy saving of 83% and 72% respectively.
It is worth mentioning that in many cities, strengthening the energy conservation and efficiency of building operations is also regarded as one of the important goals of the renovation and upgrading of existing buildings.
The Jingcheng Building, located near Liangma Bridge on the East Third Ring Road in Beijing, has been in operation for 30 years, and its basic energy consumption is relatively high.
Xiang Wei, general manager of the Urban Renewal Division of CITIC Heye Investment Co., Ltd., said for example that the HVAC system of the building at that time had a low degree of automatic control and adjustment accuracy, resulting in insufficient cooling of local spaces in summer and high room temperature in winter, and the overall energy efficiency of the system was relatively high. Low.
"In 2017, on the premise of not affecting the normal office work of customers in the building, we carried out green renovation of the building from the perspectives of safety, health, and intelligence." Xiang Wei introduced various changes: the refrigeration unit was replaced with a high-efficiency maglev unit ; Replace the gas boiler with an air source heat pump; add an intelligent integrated platform, comprehensive energy management system, building automatic control system... "In 2021, the energy cost of the building will only be 73% of that in 2016, and the carbon dioxide emissions will only be 38.6% of that in 2016. ."
Experts said that although the energy-saving renovation of existing buildings has achieved gratifying results, supporting policies and mechanisms still need to be improved.
"Currently, the green renovation of existing buildings mainly relies on financial investment, and the mechanism to give full play to the subjective initiative of owners still needs to be improved." Huang Dingxi, vice president and secretary-general of Guangzhou Urban Planning Association, suggested to explore carbon emissions trading in the building sector, and actively Improve green finance policies to support green buildings, encourage cooperation between the government and social capital, and stimulate enthusiasm for building green buildings.
The relevant person in charge of the Standard Quota Department of the Ministry of Housing and Urban-Rural Development introduced that in the next step, the Ministry of Housing and Urban-Rural Development will continue to carry out green building creation actions to further increase the proportion of green buildings; promote the green transformation of existing buildings, and improve the energy-saving and low-carbon level of buildings ; Strengthen the management of building operation and reduce the energy consumption of building operation.