## 2 Literature Review
### Carbon Footprint Accounting Boundary  
Currently, the majority of academics, both domestically and internationally, use the complete life cycle concept to calculate the building's carbon emissions, investigate the sources of the emissions for the building's entire life cycle or just a particular stage, and evaluate the building's environmental impact. For research on the full life cycle, [PERSON] [19] examined the stages of pre-production, manufacture, assembly, use, and service life, adopting a parametric model and the whole life cycle approach. [PERSON] [20] conducted a comparative study comparing conventional and low-carbon buildings, breaking down the building's entire life cycle into four phases: the manufacture of materials for building, onsite development, operation, and demolition, employing a life cycle assessment methodology. [PERSON] [21] investigated the energy efficiency and environmental effects of prefabricated construction modules in Italy. [PERSON] [22] produced an LCA model driven by carbon emission reductions for each of the six phases in the life cycle of prefabricated temporary housing. [PERSON] [23] provided evidence of prefabrication to reduce carbon emissions through a case study based on the whole life cycle theory. [PERSON] [24] separated a building's complete life cycle into five phases: designing and planning the structure, collecting the building resources, construction, operation, and demolition. [PERSON] [25] quantified a building in Shenzhen by establishing a full life cycle evaluation model for assembly buildings. [PERSON] [26] developed a framework for accounting for carbon dioxide during the construction, use, and abandonment phases of the construction process, using a complete life cycle methodology to assess its impact on the total amount of carbon emissions from the structure. For research on the physical phase aspect, to make carbon emission calculations, [PERSON] [27] separatedthe construction phase of prefabricated elements into three phases: material manufacturing and transit, component fabrication and delivery to the spot, and on-site assembly. [PERSON] [28] used the process inventory analysis method, combined with the characteristics of assembled concrete buildings, to divide the materialization phase into building material extraction and production, factory production, transportation, and assembly construction phases. [PERSON] [29] divided the materialization stage into prefabricated component production and processing, logistics and transportation, and on-site construction and installation stages, and then carried out carbon footprint analysis. [PERSON] [30] calculated the carbon footprint after looking at the variables influencing the greenhouse gas emissions of completed structures during the various phases of industrial manufacturing, transportation and shipping, and assembly construction. [PERSON] [31] established a carbon emission model for metro civil engineering to quantify the carbon emissions in each physical stage.  
Scholarly investigations on assembled houses have progressively garnered prominence, coinciding with the rapidly expanding assembled building industry in China. When deciding the border of the carbon footprint calculation, the majority of academics employ all facets of the life cycle philosophy to compute carbon emissions for the whole life cycle of assembled houses. They neglect to take into account the fact that the materialization stage, which is a critical stage in determining carbon emissions, can roughly replace the entire life cycle while lowering the computation amount. Subsequent examination of the literature reveals that the materialization phase can be further subdivided into the following: the building material production phase, the conveyance of building materials phase, the component manufacturing phase, the component phase of transportation, and the building phase.