According to statistics, construction-related industries accounted for 51% of carbon emissions, far higher than other industries, its emissions reduction on the overall double-carbon target is significant.
According to the China Building Energy Conservation Association, China's construction industry's carbon emissions are expected to peak around the 2039, nine years later than the national average.
Construction prefabricated building is the most important way to achieve environmental protection in the construction industry, and since the factory production of prefabricated building greatly reduces the pollution caused by on-site construction, improving the environmental friendliness of construction has become the main direction of construction industry reform.
The prefabricated building chain
The prefabricated building industry chain can be divided into three parts.
Upstream is architectural design and product development; midstream includes manufacturers in factories that produce components such as precast concrete and precast steel, as well as contractors that assemble components on site; Downstream is the construction project developers and construction operations unit.
The construction process of the prefabricated building is characterized by complex structural design and a large number of prefabricated components.
The prefabricated building model is design-factory-on-site installation, which is different from the traditional design-on-site construction, causes the factory to manufacture the component to install the stage to discover can not use the situation, thus causes the resources to waste.
Upstream: architectural design and product development
In the preliminary stage, the design of the prefabricated building and the development of the related assembly products need to be carried out, mainly including the R & D departments and architectural firms within the enterprises.
According to the requirements of the developer, the design enterprise carries out the personalized design of the project, and sends the drawings to the manufacturer to prefabricate the building structural components, and then transports them to the construction site to complete the follow-up construction and decoration, the final sales unit to complete the sale.
The prefabricated building design is usually divided into pre-technical planning, scheme design, master design, construction drawing design and component design (component splitting, component sample detail drawing and component node optimization) .
The process of prefabricated building industry chain is long, and the additional cost of design change is large, so the precision of component design and the matching degree with production are required to be higher With the help of information system based on BIM technology, it is helpful to improve design accuracy, reduce project cost and shorten project duration.
Midstream: the production of prefabricated components
The middle-stream production link mainly refers to the production of prefabricated components in the factory, through the module, pouring and other processes in the production line operation, mainly related to all kinds of prefabricated components manufacturers.
Among them, the production and use of precast concrete (PC component) is the core.
The capacity of prefabricated components is another key factor to determine the speed of development of assembled buildings. At present, the prefabricated building technology system is more perfect, and the component quality and construction technology level have been greatly improved, which basically solves the common quality problems such as cracking and leakage.
The fixed cost of prefabricated components accounts for a larger proportion of the prefabricated building cost. With the development of the industry and the increase of the prefabricated building works, the amortization charge of the land, plant, equipment and formwork of PC component factory will have a big space to decrease. These fixed costs would be greatly diluted, further reducing the total cost of prefabricated building.
From the perspective of regional market, a large number of prefabricated Yangtze River Delta Economic Zone have been built in Jiangsu, Anhui and Zhejiang provinces in recent years, which is also the premise of the rapid development of prefabricated building industry in these three places.
According to Frost & Sullivan, PC component 2023 will grow 65% between 2020 and 2023. The current PC component industry structure is scattered, CR5 is 44.7% .
As a result of more or less management limits, cash flow pressures, and investment capital constraints in the chain-wide development of enterprises, as well as a significant reduction in the prefabricated building demand for on-site workers, only needs the spot simple assembly, the industrial chain core value centralizes to the factory end.
In the long term, as the prefabricated building industry becomes more standardised, there will be more room for growth for the industry leaders who focus on areas such as design and manufacturing, and it can achieve the continuous improvement of profitability through scale advantage and fine management.
The level of development is uneven
In recent years, the gap in industrial scale, technical ability, talent reserve and so on between the key promotion regions and the encouraged promotion regions has gradually widened. At the same time, the level of implementation of standards vary widely, resulting in uneven project levels.
After a preliminary assessment of local prefabricated building standards, Beijing's requirements for the proportion of non-masonry internal partitions are slightly higher than the national standard; Tianjin, Guangdong, Shandong, Jiangsu, Jiangxi, Hainan, Ningxia, Xinjiang and other places have added new technologies to the list in line with local conditions, it highlights the application of new technologies in the fields of standardized design, BIM, green construction and local construction.
In some regions, the requirement of assembly rate has been lowered in order to achieve a higher proportion of prefabricated building development, and the lower assembly rate has restricted the development of technology and the exertion of efficiency to some extent.
The level of standardization is not high
At present, the most serious problem reflected by enterprises in various regions is that the low level of standardization leads to the low cost, and the comprehensive efficiency and benefit advantages are not obvious.
In terms of design, most of the projects are still designed according to the traditional way, and then the secondary disassembly and deepening design are carried out, the sizes are arbitrary and the types are various, which results in that the common sizes of prefabricated components and parts can not be fixed in the production link, can only be customized production, low utilization of the production line, die large amortization; also caused the construction link installation efficiency can not go up, the comprehensive cost down.
According to the calculation of steel structure enterprise, if the dimension of steel structure can be solidified, the steel structure cost will be saved about 15 -20% by directly mass production of section steel.
In addition, there are some problems such as lack of supervision in the production of prefabricated components, imprecise on-site assembly, common quality problems and so on.
The capacity building of the team is insufficient
The prefabricated building has set higher demands on the entire industry chain than the traditional way of construction, requiring scientific research, design, production and construction sectors to apply the principles of industrialization and technology to guide project construction, at present, the speed of the transformation of the traditional talent team is not fast enough.
According to incomplete statistics, the proportion of 2021 with experience in prefabricated building design is 12.5% . 9% and the corresponding prefabricated building construction units accounted for 9.2% . For example, in Zhejiang province, where prefabricated building are well developed, there are about 166 design units with experience in prefabricated building design, accounting for only 22.5% of the total, and about 1,378 construction units with experience in prefabricated building construction, only 10.1 per cent.
The proportion of trained skilled workers is only 1.8% of all real-name workers in the construction industry. The lack of talent pool and capacity seriously affects the sustainable and healthy development of the prefabricated building industry.
Insufficient industry chain coordination
Prefabricated building is a systems engineering, its design, production, construction and other industry chain links of mutual penetration, mutual influence, suitable for the use of EPC EPCM way for effective integration.
Statistics show that there are about 15,000 new prefabricated building 2021 projects across the country, of which 1,750 are BPC EPCM projects, accounting for only 11.6% . In addition to the small number of prefabricated building projects for which EPC EPCM have been applied, the level of project management that has been applied has also been uneven, with some projects forming consortia only at the time of bidding, there is still a lack of synergy in the actual implementation process. The disharmony of industrial chain also results in the increase of cost and the decrease of efficiency.
The “14th five-year plan” for the construction industry, published by the Ministry of Housing and urban-rural development (hereinafter referred to as “The plan”) , proposes that prefabricated building should account for more than 30% of new construction by 2025; The amount of construction waste discharged from new construction sites should be kept below 300 tonnes per 10,000 square metres. A market mechanism for construction Waste treatment and reuse has been formed. A number of green construction demonstration projects have been built.
According to the“Plan”, by 2025, the initial formation of the construction industry high-quality development system framework. The level of construction industrialization, digitalization and intelligentization has been greatly improved, the green transformation of construction mode has achieved remarkable results, and the transformation of the construction industry from large to strong has been accelerated, for the formation of a strong domestic market, building a new development pattern to provide strong support.
Guided by the government's prefabricated building development plan and incentive policies, the prefabricated building industry, as the focus of the construction industry, is expected to usher in explosive growth opportunities.