# Assessment of Carbon Emissions at the Logistics and Transportation Stage of Prefabricated Buildings
## 1 Introduction  
Massive emissions of greenhouse gases have led to global warming. This has caused extreme climate disasters, such as glacier retreat, melting permafrost, droughts, and torrential rains. These events pose a great threat to the natural balance of ecosystems and human survival. As the most significant of greenhouse gases, carbon dioxide (CO\({}_{2}\)) emissions have become an important indicator of total greenhouse gas emissions. The 26 th United Nations Climate Change Conference (COP26) summit of the United Nations Framework Convention Climate Change (UNFCCC) in 2021 urged parties to accelerate emission reduction and to align national climate action commitments with the Paris Agreement. This was designed to keep alive the hope of limiting global temperature rise to 1.5 \({}^{\circ}\)C and setting a net zero emission goal for 2050 [1]. The impact of this conference on the construction industry is, therefore, immediate and far-reaching. The construction sector accounts for approximately 42% of global greenhouse gas emissions [2], with CO\({}_{2}\) accounting for 82.9% of greenhouse gas emissions. As a major construction country, China is committed to reducing emissions and controlling temperatures to mitigate climate change, in line with the trend of the global climate governance process. China has adopted carbon emission reduction, carbon peaking, and carbon neutrality as its national strategy, aiming to achieve carbon peaking by 2030 and carbon neutrality by 2060. Therefore, reducing the energy consumption and carbon emissions in the construction industry has become an unstoppable trend. The prefabricated construction mode is production-transportation-assembly, in which the components of a building are produced in a factory and then transported to the construction site for assembly. [PERSON] et al. used the life cycle assessment (LCA) method toanalyze 200 prefabricated schools, demonstrating that prefabricated technology was more effective in reducing carbon emissions and was more environmentally friendly [3]. Therefore, advocating for the development of prefabricated buildings could help the construction industry become more industrialized. In addition, it could lead to energy use reduction over the entire life cycle of a building project. This is necessary in order to change and improve the Chinese construction industry. The entire life cycle of assembled buildings includes the materialization stage, operation stage, and demolition stage. Among these, the materialization stage is the stage with the largest carbon emissions [4]. This can be divided into three stages: factory production, logistics and transportation, and on-site assembly. By comparing the carbon emission levels of the prefabricated construction mode to those of the traditional construction methods, it can be seen that the proportion of carbon emissions in the production and assembly construction stages of assembled buildings is lower than that of traditional cast-in-place buildings. In contrast, the proportion of carbon emissions in the logistics and transportation stages is higher for the assembled buildings [5]. Regarding the prefabricated assembly building mode, currently, the transported items are no longer scattered building raw materials, but are instead prefabricated components. Given the characteristics of prefabricated components, which include large size and quantity, complex stacking, and heavy weight, it is frequently necessary to transport them in multiple vehicles. This is the main reason for the increase in carbon emissions in the transportation phase of prefabricated buildings. The logistics and transportation industry has one of the largest carbon emission rates, and the CO\({}_{2}\) generated by the logistics industry in China currently accounts for more than 25% of the total CO\({}_{2}\) emissions [6]. Furthermore, it will take a long time for new energy vehicles to replace fossil fuel vehicles; therefore, it is of far-reaching significance to explore the transportation of prefabricated buildings.