Advantages and disadvantages of prefabricated buildings

If we are to identify the factor that hinders the development or adoption of prefabricated buildings, it is, in a word, high costs. 　　In fact, the development of prefabricated buildings in our country did not begin in recent years; as early as 1999, the State Council issued relevant documents such as the \"Several Opinions on Promoting the Modernization of the Housing Industry and Improving Housing Quality.\" As one of the cities in China that was among the first to carry out pilot projects for prefabricated housing, Shanghai began work on its first such project as early as 2006. However, the high costs of prefabricated buildings result in a small market, leading to low enthusiasm among market participants, and thus slow progress in its development. 　　Theoretically, in the absence of any external factors, the materials required to build a house are relatively fixed; when comparing only the cost of materials, the costs should be fairly similar regardless of the method used for construction. In fact, the cost of prefabricated buildings is much higher than that of building houses in the traditional way. According to estimates by the relevant officials at the Municipal Market Management Office for the construction and building materials industry, the additional cost per square meter for prefabricated buildings in Shanghai compared to traditional buildings ranges from 350 to 550 yuan. Moreover, the higher the prefabrication rate (the ratio of the volume or value of prefabricated components to the total volume or value of all components), the higher the costs as well. 　　So, where does the high cost of prefabricated buildings come from? In the view of this official, the costs mainly fall into two categories. The first is process cost. Prefabricated building technology is more complex; the initial investment in research and development, as well as the machinery required for producing prefabricated components, are substantial. This results in higher costs for these components. Costs can only be reduced if the scale of prefabricated building projects is large enough to allow for high volumes of component production. The second factor is logistics cost. Only when the distance from the factory to the construction site is around 100 kilometers are the logistics costs relatively reasonable; if the factory is too far away, it becomes uneconomical. Furthermore, looking at the entire industrial chain, in prefabricated building construction, the coordination between various stages – from planning and design to production, transportation, and construction – is not yet smooth, which adds to the costs. 　　“In recent years, in order to reduce the costs of prefabricated buildings, relevant authorities in Shanghai have successively formulated and introduced a number of policies to guide and support this sector. ”It is reported that the current support policies mainly consist of rewards based on the building area; for residential projects that voluntarily construct prefabricated buildings, there is an incentive allowing the prefabricated parts of the exterior walls or composite walls to be excluded from the calculated building area (up to 3% of the allowable building area above ground level). Not only that, but there are also more direct financial subsidies aimed at promoting energy efficiency in construction. For prefabricated housing projects that meet the requirements, a subsidy of 60 yuan per square meter is provided if the degree of prefabrication reaches 15% or more, and 100 yuan per square meter if the degree of prefabrication reaches 25% or more. For prefabricated public building projects that meet the standards required for green building demonstration projects or high-standard building energy-saving demonstration projects, they will also be given priority in receiving subsidies from special funding programs aimed at supporting energy savings in buildings, and so on. 　　However, at present, these incentives and subsidies are still far from covering the additional costs of prefabricated buildings.

Various “savings” that are overlooked In the case of prefabricated buildings, many people only focus on the increased costs, while easily ignoring the efficiency improvements it brings. 　　In the eyes of industry experts, the term “building cars” is used to describe prefabricated housing because, just like the automotive industry, it belongs to the advanced manufacturing sector. Manufactured uniformly in factories, it enables maximum savings in energy, land, water, and materials throughout the building’s entire life cycle. Based on calculations of the prefabricated housing projects currently under trial in Shanghai, the production and construction process of prefabricated buildings can result in energy savings of around 50%, water savings of around 60%, material savings of around 20%, land savings of around 20%, as well as a reduction in construction waste by around 80%. Moreover, in terms of the benefits of construction, it can also be increased by 4-5 times. 　　Previously, when visiting the component factory of Faraday Residential Industrial Group in the Lingang industrial park, the reporter also witnessed firsthand the high level of production efficiency. A batching machine is operating in an orderly manner, dropping concrete from left to right into the lower feeding tray, where it is then transported by a cart to a curing kiln nearby. After several hours of resting, a standard exterior wall panel is formed. From the fabric to its insertion into the curing kiln, the entire process is controlled by motors; it takes no more than 5 minutes. The production efficiency and quality are many times higher than those achieved through manual methods. Thereafter, this exterior wall panel will be sent to the construction site along with many other components that have been pre-fabricated in the factory, to be used in the construction of the residence. Moreover, by constructing houses in this way, it is possible to conduct a \"roadshow\" using computer software in advance, which allows for a 70% reduction in the actual on-site construction time; the overall time cost is only 1/3 of that of traditional construction methods. Taking a 30-story fully furnished residential building as an example, with prefabricated construction methods, the process from start to completion can be completed in just over 10 months, whereas traditional methods require at least two to three years. 　　If prefabricated buildings can achieve maximum energy savings as well as reduce waste and carbon emissions, then their benefits are primarily environmental and social in nature. For developers and builders, significantly reducing the project timeline and saving time costs thus creates greater market opportunities and benefits. 　　It is also worth mentioning that although the initial investment cost for prefabricated buildings is higher, this does not mean they are expensive \"luxuries\" that are difficult to replicate. In the view of Li Jinjun, deputy chief engineer at the Technology Center of East China Architectural Design and Research Institute Co., Ltd., when considering investment in construction, it is not enough to focus only on the initial construction costs; the maintenance costs after the building is completed must also be taken into account. Prefabricated housing projects may require higher investment during the construction phase, but their maintenance costs later on are reduced, so the overall cost is not that high. 　　Looking at the four prefabricated housing projects developed by Vanke, namely Siji Huacheng, Jinse Mile, Chenghua Xinyuan, and Qinglin Jing, these projects include nearly 1,800 residential units. Since their delivery began in January 2010, there has been very little need for repairs, with only one case of exterior wall leakage. The reason is that prefabricated building components are integrated and produced in factories, allowing for better control over quality. It is said that the tensile strength of its wall tiles is about 9 times higher than that of traditional methods.