Part　1

The core of prefabricated buildings:
Prefabrication of parts, construction splicing

A prefabricated building is a building that is assembled on the site with prefabricated components produced by a factory. The assembly-type construction mode adopts standardized design, factory production and assembly construction, and transfers a large number of on-site operations in the traditional construction mode to the factory. It is a new type of construction production method that can realize the sustainable development of energy saving, environmental protection and maximum life cycle value of building products.

Part　2

Main features of prefabricated buildings

Part　3

industrial chain of prefabricated building industrialization

Part　4

There are three main technical models for prefabricated buildings.

Prefabricated concrete structure (PC,Precast Concrete), steel structure and wood structure, the three technologies are self-contained, each has its own advantages.

　　prefabricated concrete structure:It is a concrete structure composed of prefabricated components as the main force components. It can be roughly divided into two stages: factory prefabrication and on-site assembly.

　　Steel structure:It is a structure composed of steel materials. It is mainly composed of steel beams, steel columns, steel trusses and other components made of steel and steel plates, and the components or components are usually connected by welds, bolts or rivets.

　　Wood structure:It refers to a construction method in which the structural load-bearing components mainly use wood. Modern wood structure components are processed by laminating, gluing, metal connection and other processes to form a building structure with far better performance than logs.

•One of the technical models: prefabricated precast concrete

-Relatively low cost, the most widely used

Prefabricated concrete (PC) refers to the standardized processing and production of concrete products in the factory. It has the characteristics of good structural performance, high product quality, and fast construction speed. It is suitable for all kinds of industrialized buildings and has good flexibility and applicability. It mainly includes products such as prefabricated PC wall panels, folding floors, stairs and laminated beams. Because it is in line with the traditional cast-in-place concrete structure with wide application, it is also the most smooth promotion and the largest coverage among the three structural systems of prefabricated buildings. Judging from the first batch of 64 assembly building demonstration projects identified by the Ministry of Housing and Construction, concrete structures accounted for the largest proportion of 64%, with a total of 41 items (19 steel structures and 4 wood structures). The concrete industry developed earlier and has advantages in cost, but the cost competition in the field of PC components is fierce, and the optimization space is limited, it is difficult to replace the traditional cast-in-place concrete in the short term. Compared with the prefabricated steel structure, the prefabricated concrete building occupies the cost advantage, but it is difficult to meet the design requirements of wind resistance, earthquake resistance, super height and span.

Assembly concrete structure construction cost is low, suitable for a wide range of multi-storey, small high-rise office buildings, residential buildings. On the basis of the traditional technical framework, the fabricated concrete structure focuses on the componentization of exterior wall panels, interior wall panels, floor slabs and other components, and the componentization rate is 40% ~ 50%. If it is extended to the integration of on-site decoration, the cost can be further reduced to close to the traditional technical cost, and the high efficiency of building one floor in about 5 days can be realized. In a wide range of multi-storey buildings, especially in the residential field has a wide range of application scenarios.

•Technical model II: fabricated steel structure

-Good seismic resistance, suitable for high-rise building fabricated steel structure is mainly composed of steel beams, steel columns, steel trusses and other components made of steel and steel plates, and the components or components are usually connected by welds, bolts or rivets. Widely used in large factories, venues, super high-rise and other fields.

At present, the domestic steel structure industry has a high degree of marketization, low industry concentration and serious homogenization competition. According to the process and use, the steel structure industry can be divided into light steel structure, multi-high-rise steel structure, space steel structure three sub-industries. The light steel field represented by the factory building is widely used, the technology is relatively mature, the entry barrier is relatively low, the market is scattered and the competition is the most fierce; in the field of multi high-rise steel structure, due to the high technical content of steel structure engineering, the production and installation are difficult, the product quality and precision requirements are high, and the competition is more relaxed than the light steel market; and the spatial structure is mainly used in large-span public buildings such as stadiums, there are strict requirements on capital qualification, product quality and precision, high entry threshold, and the most gentle competition among the three.

Application Scenarios of Steel Structure

•Technical model three: fabricated wooden structure

-Highest cost, limited application scenarios determined by national conditions

The prefabricated wooden structure takes wood as the main force system. Because the wood itself has the advantages of earthquake resistance, heat insulation, energy saving, sound insulation, comfort, etc., coupled with the economy and materials everywhere, in foreign countries, especially in the United States, wood structure is a common and widely used building form. However, due to China's large population, large housing demand, per capita forest resources and wood reserves are scarce, wood structure is not suitable for China's construction development needs. In addition, China's "wood structure design code" clearly stipulates that the number of wood structure buildings can not exceed 3 layers, and the maximum length and area are limited. In recent years, most of the wooden structures are low-density and high-grade wooden villas, mainly to cater to a certain level of consumers' preference for wood, a traditional natural building material, and the overall volume of the industry is small.

The wooden structure is restricted by the code

Comparison of several models of building industrialization

China's concrete technology developed earlier, has a good industrial foundation, and precast concrete has a cost advantage, can be widely used in multi-storey, small high-rise buildings. Steel structures are widely used in super high-rise and large-span buildings due to their good seismic resistance. The state has more subsidies for steel structures, which to some extent makes up for the disadvantage of high costs. At present, China has formed the largest share of assembled concrete structure, followed by steel structure.

Part　5

Assembly building compared to the traditional building model:
Energy conservation and environmental protection, provincial construction period

Compared with traditional irrigated buildings, prefabricated buildings have inherent advantages in construction cycle, resource consumption, energy conservation and environmental protection. In terms of operation mode, the traditional construction method adopts semi-manual operation, and the concrete is cast in place on the construction site, which is easy to produce a large amount of waste water, noise and dust, resulting in water pollution and dust pollution. It takes a long time from watering and setting to installation, which seriously affects the construction rate. Due to the lax control of material procurement or entry acceptance, the large difference in the proficiency of different workers, and the poor management of the construction site, the construction quality cannot be guaranteed. In the process of pouring, the waste of cement, steel, wood and other auxiliary materials is serious, and the amount of manual work in the installation process is large, so there is a high hidden danger of safety accidents. Prefabricated building components mostly rely on large-scale production of molds in factories. A controllable factory environment can better ensure the quality of components and components, save building materials, and have stable and reliable quality. After being transported to the construction site, the professional construction team will directly carry out hoisting and installation. The amount of manual work is less, the project time is short, and the corresponding accident rate is also low. Therefore, prefabricated buildings have inherent advantages.

30%-50% reduction in labor

Compared with the traditional cast-in-place building, the prefabricated building significantly reduces the labor consumption by 30% ~ 50% (related to the prefabrication rate), and has obvious advantages in the labor consumption. The prefabricated building significantly reduces the labor consumption in the aspects of steel bar binding and formwork support on the construction site, and a large number of prefabricated components on the site are constructed by dry method, thus greatly reducing the wet operation on the site.

Analysis of Labor Quantity of Prefabricated Building and Traditional Building

Dramatically shorten the construction period

For the hardcover delivery project, the parts and components of the assembly building are processed in the factory, assembled on site, water and electricity and interior decoration can be interspersed in the main construction phase, which will significantly reduce the total construction period of the assembly building. At the same time, with the domestic assembly construction process continues to mature, the duration will be further shortened.

Comparison of Cast-in-place and Assembled Construction Period with 30-storey Hardcover Housing Project

The amount of steel and concrete used increased slightly, and the amount of water, electricity and construction waste for the project decreased significantly.

Compared with the current pouring structure, the assembly building reduces the loss of water, electricity, template and garbage by 20% to 40%, and the assembly building has obvious advantages in four sections and one environmental protection.

Environmental protection advantages of prefabricated buildings

Comparison of Architectural Industrialization and Traditional Architectural Mode

Part　6

International experience:
Government-led, from quantitative change to qualitative change

•Major countries: choose the development path according to the national conditions, the current construction industrialization rate is much higher than the domestic

After World War II, Europe has begun to rapidly promote the industrialization of construction. The industrialization of construction, and prefabricated buildings, can be traced back to the prefabricated apartment idea proposed by British engineer John Alexander Brodie in the early 20th century, but his idea has not been accepted by many people. It was not until after World War II that the industrialization of construction reached its peak with the vigorous promotion of prefabricated buildings in the war-hit areas such as Britain and France. Its development background is mainly based on three conditions: good industrial foundation, labor shortage and large construction demand.

A house built on the PC model in 1903

Fabricated buildings widely used in Europe after World War II

Since the 1990 s, the industrialization of construction in developed countries has entered a mature stage. Industrialization in developed countries has roughly gone through a period of initiation, development and maturity. After nearly a century of development, the industrialization of construction in developed countries has entered a mature period: there is a perfect "factory production, on-site assembly" construction system, pay attention to product quality and cost-effective at the same time, further reduce material consumption and environmental load, the development of resource recycling type green housing.

The Empire State Building uses PC floors and PC curtain walls, etc.

Sydney Opera House uses prefabricated steel girders and PC floor slabs

Most of the developed countries construction industrialization degree of more than 70%. The rate of construction industry in Japan and Britain is about 70%, 75% in the United States, and 80% in France and Sweden. In contrast, China's current construction industry industrialization rate is only 5%.

The Process of Construction Industrialization in Developed Countries

Comparison of Construction Industrialization Rate between Major Developed Countries and China

Source: Economic Observer, CITIC Securities Research.

Combined with national conditions, China will be prefabricated concrete structure, steel structure, wood structure as a supplement. Major major cities in the United States are dominated by prefabricated concrete structures and steel structures, while small cities are dominated by wood structures and light steel structures. France mainly uses concrete prefabricated frame structures, taking into account steel structures and wood structures. Britain's construction industrialization is based on a large-volume modular system of steel structures. However, in neighboring Japan, due to frequent earthquakes, steel structures account for a high proportion of newly-added prefabricated buildings, with steel structures, wood structures and concrete structures accounting for 87.3 respectively, 9.9 per cent and 2.8 per cent.

Characteristics of prefabricated industrialization in major developed countries

•Optimal path: government-led, quantitative change leads to qualitative change

Throughout the history of construction industrialization in developed countries, although countries have chosen different industrialization models due to differences in topography, industrial base, population structure and history and culture, the entire industrialization process has many common characteristics.

•The leading role of the government is obvious

The British government has made it clear that the construction production field needs to achieve the specific goal of "reducing costs by 10%, shortening time by 10%, reducing defect rate by 20%, reducing accident rate by 20%, increasing labor productivity by 10%, and finally achieving a 10% increase in output value profit margin" through new product development, intensive organization and industrial production; japan supports the advancement of construction industrialization through government-led thematic research, financial subsidies, technical guidance, and loan support.

Japan's construction industrialization government leading role is obvious

The industry standard specification system is perfect, universal and strict. Congress passed the National Industrialized Housing Construction and Security Act in 1976. In the same year, the U.S. Federal Department of Housing and Urban Development (HUD) promulgated the U.S. Industrial Housing Construction and Safety Standards (referred to as HUD Standards), which regulates design, construction, strength and durability, and fire resistance. Subsequently, the federal industrial residential installation standards were issued, which were used to review the installation manuals and state installation standards of all manufacturers. Japan has established a good residential parts (BL) certification system and a residential performance certification system, and the Japan Prefabrication Association has also published detailed design specifications for various industrial models. Germany, which is famous for its preciseness, has formulated a comprehensive and detailed specification system, all products must issue inspection reports or product quality statements that meet the requirements of relevant specifications.

Germany's huge and comprehensive system of prefabricated building codes

Experienced from the pursuit of quantity to focus on quality process. In order to meet the demand for a large number of houses, countries in the early stage of industrialization built houses quickly and in large quantities. With the improvement of economic level, quality and function are paid more and more attention. Combined with the continuous enhancement of environmental protection awareness, new green energy-saving and resource recycling buildings have become the mainstream.

The Process of German Construction Industrialization

Part　7
China has entered the stage of rapid development of prefabricated buildings
More than 55% CAGR in past 3 years

The course of China's construction industry industrialization can be roughly divided into four stages: the earliest stage of construction industrialization, the ups and downs of construction industrialization, the promotion of construction industrialization, and the rapid development of construction industrialization.

In the early stage of construction industrialization in the 1950 s, China began to learn the Soviet Union's multi-storey brick experience. From 1950 to 1975, China comprehensively studied the Soviet Union, including all kinds of architectural design codes translated from Russian. During the period, the State Council issued the "Decision on Strengthening and Developing the Construction Industry", emphasizing that the construction industry must actively develop in the direction of "design standardization, component production industrialization, and construction mechanization. At one time, under the impetus of the state, almost all buildings had "prefabricated assembly elements".

From 1976 to 1995, the industrialization of China's construction industry has entered a long period of ups and downs for 20 years, experiencing stagnation, development and re-stagnation. The 1976 Tangshan earthquake survey showed that the prefabricated buildings built in accordance with the norms at that time had poor seismic performance and collapsed seriously. After the earthquake, the whole country divided the seismic intensity area, promulgated a new code for seismic design of buildings, and cast-in-place slabs became the mainstream; subsequently, the "four modernizations, three reforms, and two enhancements" were proposed, and the industrialization of buildings ushered in a round of peaks and standardized design systems. Rapid establishment, a large number of large slab buildings and block buildings have landed. At the end of the 1980 s, due to the emergence of a series of problems such as waterproofing, cold bridges, and sound insulation, coupled with the emergence of the mechanization of cast-in-place concrete, the development of prefabricated buildings suddenly stopped again.

From 1996 to 2015, China's construction industrialization has entered a period of development and upgrading. In 1999, "Several Opinions on Promoting the Modernization of the Housing Industry and Improving the Quality of Housing" was issued, which clarified the development goals, tasks, and measures of the modernization of the housing industry. However, the commercialization of housing, diversification requirements, a large number of cheap labor force into the city for employment and other factors led to the large-scale development of the cast-in-place system, this stage of the proportion of assembly buildings is still low, the development is slow.

Since 2016, the industrialization of China's construction industry has entered a period of rapid development. Since entering the "13th Five-Year Plan", after the State Council issued the "Several Opinions on Further Strengthening the Management of Urban Planning and Construction", the scale of the prefabricated construction market has shown a significant accelerated development trend, and my country's construction industrialization has officially entered a period of rapid development. The number of components and accessories manufacturers is increasing rapidly. By the end of 2016, there were 156 manufacturers nationwide, up 20% from 2015. In terms of industry output value, in 2018, the national prefabricated buildings were about 0.2 billion square meters, with an industrial scale of 523.4 billion billion yuan, with a compound growth rate of 55% in the past three years.

2011-2018 China's assembly building market size.

Source: Combined with Intellectual Research Consulting, CITIC Securities Research Department.

Number of Fabricated Components Manufacturing Enterprises in China

Source: Forward-looking Industry Research Institute, CITIC Securities Research Department.

China's 13 Five-Year Plan Construction Industrialization Development Characteristics

Source: A Brief Discussion on Housing Design and Modernization of Housing Industry

Part　8

Multi-dimensional driving force:
Policies are constantly on the ground, and the labor factor is fundamental.

Since the Development and Reform Commission and the Ministry of Housing and Urban-Rural Development issued the "Green Building Action Plan" in 2013, the state has intensively promulgated policy documents on the promotion of prefabricated buildings. Clear requirements have been made in many aspects such as development planning, standard system, industrial chain management, and project quality. In February 2016, the State Council issued the "Several Opinions on Further Strengthening the Management of Urban Planning and Construction", marking that the country has officially promoted the promotion of prefabricated buildings to the height of the national development strategy. The "Opinions" emphasized that my country must vigorously promote prefabricated buildings and build national-level prefabricated production bases; accelerate policy support, and strive to use about 10 years to make prefabricated buildings account for 30% of new buildings.

Interpretation of national policies on construction industrialization since 2016

Source: Prospective Industry Research Institute

In March 2017, the Ministry of Housing and Construction issued the 13th five-year Plan of Action for Prefabricated Buildings, which made it clear that by 2020, the proportion of prefabricated buildings in new buildings in the country will reach more than 15%, of which key areas will reach more than 20%, actively promote areas to reach more than 15%, and encourage areas to reach more than 10%.

Guiding Opinions of the General Office of the State Council on Vigorously Developing Prefabricated Buildings

Source: Website of the General Office of the State Council

Proportion of regional prefabricated building planning by 2020

Source: 13th Five-Year Plan of Action for Prefabricated Buildings

National Prefabricated Building Development Plan by 2020

Source: 13th Five-Year Plan of Action for Prefabricated Buildings

Local governments have followed the pace of the country and issued relevant documents to promote prefabricated buildings. Incomplete statistics show that governments at or above the prefecture level and their relevant departments have issued more than 100 policy documents on prefabricated buildings. At the current time point, the national top-level design is perfect, local rules land, the next ten years assembly building will take advantage of the policy east wind to achieve high-speed development.

Source: CITIC Securities Research Department

Part　9

The development of assembly is the inevitable way

•The demographic dividend is disappearing and labor costs are rising rapidly.

The traditional concrete pouring mode is a typical labor-intensive mode of production. In the past few decades, the cast-in-place concrete building model has benefited from my country's abundant labor resources and has developed extensively. But with the gradual disappearance of the demographic dividend and the rapid rise in labor costs, this model will be unsustainable.

The growth rate of migrant workers in China began to decline in 2011, and the labor force declined after peaking in 2013. According to data released by the National Bureau of Statistics, the total number of migrant workers nationwide in 2018 was 0.288 billion, an increase of 0.6 percent over the same period last year, a decrease of -3.8pcts from 4.4 percent in 2013. The working population aged 16-60 began to decline after peaking in 2013. in 2018, the number of working people in the country 0.911 billion, accounting for 65.26 percent of the total population.

Rapid decline in the number of migrant workers

Decline in the number and share of the working population aged 16-60

Source: Migrant Workers Monitoring Survey Report

The age of migrant workers continues to increase, the proportion of young migrant workers is getting lower and lower, and the proportion of migrant workers engaged in the construction industry has dropped significantly. The average age of migrant workers in 2017 is 39.7 years old, 0.7 years higher than that in 2016. The proportion of migrant workers under 40 years old is 52.4, -1.5pcts lower than that in 2016, while the proportion of migrant workers over 50 years old is +2.2pcts to 21.3 from 2015. At the same time, the proportion of migrant workers engaged in the construction industry is gradually declining, accounting for 18.9 percent in 2017, down -0.8pct from 2016.

Age composition of migrant workers%

Labor costs in the construction industry are rising rapidly. In 2009-2017, the CAGR of wages in private enterprises in the construction industry was 12.3 per cent and that in non-private enterprises was 11.6 per cent, higher than the GDP growth rate over the same period. As traditional construction is a labor-intensive industry with sufficient competition, the increase in labor costs will further compress the limited profit margins.

Average construction wages in private and non-private units

Source: Wind, CITIC Securities Research.

The per capita cost of migrant workers in the construction industry continues to rise.

Source: Migrant Workers Monitoring Survey Report

The rapid rise in labor costs will greatly reduce the cost disadvantage of prefabricated buildings. Assembly building is a kind of intensive production mode, the industrial chain is highly mechanized, and the labor force is greatly reduced. For example, there are less than 10 workers on the production line of a professional factory with an annual production capacity of 1.2 million square meters, while the traditional manual operation requires more than 200 workers to produce the same number of floors. For a 30-storey building, only 12 workers are required to work for 180 days using the fabricated construction mode, which is at least 30% more effective than the traditional construction.

China's urbanization rate will continue to rise, and the weakening of the demographic dividend will accelerate the upgrading of the traditional construction industry to the industrialization of construction. The growth rate of the population employed in the construction industry has declined, and the imbalance between supply and demand has prompted labor costs to rise year by year. The construction industrialization is highly mechanized and the labor cost is low, which has obvious advantages compared with the labor-intensive cast-in-place construction mode.

•Large-scale production superimposed on rising labor costs will rapidly strengthen the economic applicability of prefabricated buildings.

The incremental cost of the assembly construction model comes mainly from prefabricated components. Taking the prefabricated concrete structure as an example, according to the calculation of a public rental housing project by "Construction Economy", the incremental cost of the prefabricated construction mode is about 695 yuan/m2. In electrical engineering, water supply and drainage engineering, the assembly type has obvious advantages, but the unit price difference caused by precast concrete components is 1435 yuan/m2.

Cost Comparison of Assembly Design and Cast-in-place Design of a Public Rental Housing Project

Note:The construction area is 4714 square meters, the case is not universal, and the policy preference of PC structure is not considered.

Source: The Construction Economy

The cost of prefabricated components can be divided into variable costs and reduced costs for large-scale production. The former includes the cost of raw materials such as steel and concrete, accounting for about 42%; the latter mainly includes molds, labor costs, management fees, etc., which can be effectively reduced through large-scale production, accounting for about 58%.

Cost composition of precast concrete components

Source: "The impact of PC deepening design on the overall cost of assembly"

The main reason for the high cost of prefabricated buildings is that the advantages of scale have not yet been reflected, and with the improvement of capacity utilization, the cost will be greatly reduced. According to the calculation of a certain project by the Housing Industrialization Promotion Center of the Ministry of Housing and Urban-Rural Development, the ex-factory price is 3344 yuan/m for a building. However, for large-scale projects, the ex-factory price can be reduced to 2563 yuan/m with a difference of 780 yuan/m. Assuming that other conditions remain unchanged, when the production line with an annual production capacity of 150000 cubic meters is loaded at 18%, the average selling price of prefabricated components is 3200 yuan/m to achieve profitability, while when 80% production capacity is achieved, the average break-even price of prefabricated components is only 1640 yuan/m.

Comparison of prefabricated exterior wall prices for single buildings and larger-scale projects

Note:Large-scale projects are calculated according to 100000-square-meter residential projects.

Source: Introduction to Prefabricated Architecture

•Taking into account government subsidies, PC assembly is expected to be on par with traditional cast-in-place costs by 2021.

According to the standard concrete small high-rise residential buildings published in the "Consumption Quota for Prefabricated Construction Projects" as an example, the cast-in-place construction cost in 2018 is 2061 yuan/m2, of which the total construction and installation cost is 1752 yuan/m2. The 60% PC rate of prefabricated construction cost is 2556 yuan/m2, of which the total construction and installation cost is 2171 yuan/m2. Based on this data, PC assembly buildings with an assembly rate of more than 40% are expected to be on par with the cost of cast-in-place buildings by 2021.

Core Assumption 1:The annual growth rate of labor costs is 7.2 per cent of the average increase in the income of migrant workers in the construction industry over the past five years.

Core Assumption 2:The cost of cast-in-place building materials is an inflation rate of 2%. Considering the increase in scale generation and capacity utilization, the material cost growth rates of 20%, 40%, 50% and 60% PC rates are-1%,-4%, -6.5 and-7% respectively.

Core Assumption 3:The cost of using machinery is an inflation rate of 2%.

Core Assumption 4:Gross profit margin of productionis 5%.

Core Assumption 5:The organizational measure rate is 5%, the enterprise management rate is 5%, and the tax rate is 9%.

Core Assumptions 6: The subsidy policy is 50% tax collection and refund, and only buildings with a PC rate of more than 40% (inclusive) enjoy subsidy concessions.

Standard concrete small high-rise residential cast-in-place and assembly cost calculation.

Source: "Consumption Quota for Assembly Construction"

Standard concrete small high-rise residential cast-in-place and assembly cost trends.

Note:Buildings with a PC rate of more than 40% can enjoy tax benefits.

Source: CITIC Securities Research Department

According to the requirements of each region, according to the appropriate implementation of prefabrication rate requirements

To be sure, the cost of the current assembly building is higher than that of the cast-in-place structure. The higher the prefabrication rate, the higher the cost increment. Each region should implement the lower limit of the prefabrication rate according to the regional requirements.

Root house type standardization, more combinations and less specifications

The standardization and serialization of the design of residential units, following the design principle of "less specifications and more combinations" of prefabricated components, ensure the reuse rate of prefabricated component molds, and effectively reduce the cost of prefabricated component production. Vanke Group estimates that if the turnover of component templates is increased from 60 to 70 times to 100 times, the cost of molds will be reduced by 80 to 100 yuan/m3.

Select reasonable parts connection form

At present, there are three commonly used connection forms: sleeve grouting connection, spiral stirrup restraint slurry anchor lap connection, metal bellows slurry anchor lap connection technology. The sleeve grouting connection is more expensive than the other two forms of connection. The latter two connection methods have their specific scope of use. Under the premise of ensuring safety, the latter two connection methods are preferred, which can greatly reduce the cost.

Attach Importance to the Connection Form of Force Reinforcement for Vertical Members

Source: Guiyang Architectural Design Institute

Select reasonable prefabricated plant site and control transportation radius

Based on the estimation that freight accounts for 6-8% of sales, the reasonable transportation radius is about 120km-180km. The transportation route should consider the requirements of vehicle height limit and weight limit, and reasonably plan the transportation route. Large-scale production overlay labor costs will accelerate the economy of the assembly construction model. With the vigorous promotion of prefabricated buildings, the output of prefabricated components is increasing, the standardization rate is greatly increased, the internal resources of production enterprises are fully utilized, the scale effect is gradually emerging, and the cost of prefabricated construction mode will decline rapidly with the rapid rise of labor cost, which is expected to be lower than the traditional cast-in-place construction mode in 2025.

Part　10

Industry direction is clear

•Precast concrete and precast steel structures will become the mainstream of the industry.

Precast concrete and steel structure will become the main technical mode of assembly building in China. Precast concrete structure and steel structure will become the mainstream technology mode of the industry due to policy, practicality, safety and other factors, wood structure due to more restrictive factors will account for less. At present, China has formed the largest share of assembled concrete structure, followed by steel structure. According to the number of the first batch of 64 assembly demonstration projects identified by the Ministry of Housing and Construction, concrete structures accounted for a maximum of 64%, a total of 41, 19 steel structures, 4 wood structures.

1) It has been confirmed in the industrial path of developed countries.From the perspective of the industrial path of mature developed countries, prefabricated concrete structure and steel structure are the two most widely used prefabricated construction modes. The United States is dominated by prefabricated concrete structures and steel structures, while European countries such as the United Kingdom and Sweden are dominated by prefabricated concrete structures, supplemented by steel structures and wood structures.

2) Under the guidance of national policies and the influence of China's industrial structure.From the perspective of national policy, the policy support of prefabricated concrete structure and steel structure is relatively strong, and wood structure is rarely mentioned; China has a good industrial foundation of steel and concrete, with large production capacity, extensive layout and mature technology, which can provide sufficient raw materials for the rapid promotion of prefabricated buildings, while wood resources are relatively scarce, which can not meet the rapid promotion of construction industrialization.

3) determined by the characteristics of the technical model itself.The construction cost of prefabricated concrete structure is low, which is suitable for multi-storey, small high-rise office buildings and residential buildings with large quantity and wide range; the construction cost of steel structure is slightly higher, but the seismic resistance is good, which is suitable for high-rise buildings, especially super high-rise buildings; the construction cost of wood structure is the highest, and the design specification is more restrictive, which is difficult to be applied on a large scale, and is only suitable for some luxury low-rise.

•Enterprises with integrated and integrated assembly building industry chain are expected to take the lead.

Referring to the case of Kotea (Katerra), a successful wood structure assembly enterprise in the United States, the core competitiveness of assembly enterprises in the future will be the ability to integrate the entire industrial chain of assembly buildings: covering the three major areas of design and development, supply chain management and construction management, and connecting them in series with a technology platform. The traditional single project-oriented management model in the construction industry is replaced by a product-oriented and systematic project management model.

Key Competitiveness 1:Technology platform and systematization are the basis of project management. Kotea spent a lot of money to migrate the advanced technology of the world's top 500 companies to the construction industry, and at the same time vigorously developed software and hardware in the fields of design and construction, which improved the efficiency of design, supply chain, assembly and construction, and strengthened the three The integration of the field realizes the integration of design, supply, processing and assembly. The company's technology platforms include the global SAP HANA database platform and Cotea's market analysis platform, which can mine data from real estate and construction. Mobile APP helps the company connect the labor force in the market. Internet of Things tools can optimize construction plans, track material inventory, etc.

Key Competitiveness 2:Innovative design patterns-a balance of standardization and personalization. Based on Kotea's own component database, the company can complete a personalized design plan with standardized assembly components, interior supplies and finished products like building blocks.

Key Competitiveness 3:Strong global supply chain-saving on material costs. Kotea interfaces BIM with the supply chain system, integrates the list of materials required for all engineering projects, synthesizes small orders into large orders, reduces communication costs with many material suppliers, and enhances the company's bargaining power at the time of procurement, thereby reducing procurement costs.

Key Competitiveness 4:Step-by-step assembly construction-fast and high-quality completion of the project. With the collaboration of supply chain management and BIM technology, Kotea is able to optimize the construction and assembly plan in advance and complete the assembly tasks accurately and orderly according to the established plan on the construction site. At the same time, the company also moved the assembly workers from the construction site to the assembly component factory, making the assembly workers more familiar with the construction process and process, reducing the loss of materials and time in the construction, and completing the construction project quickly and with high quality.

Through the advanced Kotea mode, the company integrates design and research, material supply and assembly construction, and completes the construction project like manufacturing mobile phones, which greatly improves the construction efficiency of the project. The project with the original construction period of one year can be reduced to March-April. Through the integration of design, supply, processing and assembly, the project cost is reduced, the cost is reduced by about 30%, and the profit margin of the project is improved.