Construction industrialization is growing rapidly and has received significant attention worldwide in recent years. The industrialization of construction results in several benefits, including the promotion of sustainable construction and the development and application of prefabrication techniques. The Prefabricated Rebar Cage (PRC) is an emerging solution applied to high-rise buildings as a replacement of the In-situ Reinforcing Bar (ISRB) construction method. This paper investigates the cradle-to-site carbon emissions of PRC, and compares the results with those of conventional in-situ rebar construction methods for high-rise buildings. The cradle-to-site cycle is divided into three stages, namely, material preparation, transportation, and on-site construction. For the material preparation stage, it is found that CO₂ emissions are increased by 3% when using PRC due to the operation of machinery during the prefabrication process. In the transportation stage, CO₂ emissions are found to increase by 3.3 times for PRC, as there is more transportation required for PRCs than for conventional construction methods. During the on-site construction stage, the PRC method demonstrates its advantages by reducing CO₂ emissions by 44.7%, which is attributed to decreased hoisting frequency and lower mechanical utilization for fewer joining activities. Overall, CO₂ emissions can be reduced by 1.24% by adopting the PRC method for high-rise buildings, and it is therefore recommended to adopt PRCs for this purpose. This research studies carbon emissions of PRC and contributes to promoting the sustainable development of prefabricated building techniques.

With the improvement of China’s economic strength, the energy consumption of public buildings is continually increasing, notably for hotels. The energy consumptin of a hotel accounts for more than 15% of its revenue, and the average energy consumption per floor area is more than 10 times that of urban residents. Therefore, the energy-saving retrofit of existing hotels is imperative. This study investigates the economic evaluation methods for existing hotel retrofit projects, and constructs an economic evaluation model using economic evaluation and cost-effectiveness ratio as the base. The energy-saving retrofit measures of 15 existing hotels in Jiangsu Province, China, are used as a case study to demonstrate the research framework. The results indicate that the heating, ventilation and air conditioning (HVAC) system, monitoring system, lighting system, domestic hot water system, and building envelope system are the five energy-saving retrofit technical measures with the highest application ratio. The average dynamic investment payback period of hotels in Jiangsu Province is 2.96 years, which meets the requirement of no more than 10 years specified in the energy-saving building standard. The cost-effectiveness ratio of different technologies differs significantly. Lighting and kitchen systems have the highest energy-saving efficiency, followed by monitoring systems, while HVAC and domestic hot water systems have the lowest. The research presented in this paper contributes to the economic evaluation of the energy-saving retrofit of hotels.

Currently, modular building is undergoing vigorous development in China, and has provided a significant advantage in many fields, but its quality is difficult to guarantee. The key is to improve the design process, shorten the development cycle, and enhance competitiveness. Therefore, it is necessary to establish and optimize the design process of modular buildings. This article was based on the DSM and adopted a parallel design to model the modular building design process. Based on this, the design process was analyzed and optimized to shorten the development cycle and reduce costs. At the same time, considering the differences in attributes between different stages of the modular building design process, a DSM model with different resolutions was constructed based on the content and interrelationships of modular building design. The schedule and cost of the design process were evaluated through simulation, the differences between different resolution models were compared, and a more reliable estimate of the schedule and cost of the design process was obtained. Considering the workload and difficulty of high-resolution modeling, an approximate estimation method based on low-resolution modeling was proposed to alleviate the dependence on high-resolution models and modeling costs to some extent, thereby effectively improving the predictability of the design process and providing necessary reference for product design management personnel.

Jiangsu Province is a region with a high concentration of economy and population in China, as well as a spatial unit with relatively concentrated carbon emissions. It is also the pioneer in achieving carbon peak. Analyzing the factors influencing carbon emissions and predicting the peak year of carbon emissions will help Jiangsu Province clarify the direction of carbon reduction and take the lead in achieving carbon peak. This article selects relevant data from Jiangsu Province from 2005 to 2020, uses the STIRPAT model to analyze the influencing factors of carbon emissions in Jiangsu Province, predicts the carbon emissions and peak times of 13 prefecture-level cities in four different scenarios, and constructs a carbon peak prediction model to calculate the carbon peak pressure, carbon emission reduction potential, and carbon peak driving force of each prefecture-level city. Research has found that the population size, wealth level, technological level, urbanization level, and industrial structure have significant impacts on carbon emissions in Jiangsu Province. The prediction results for carbon peak in 13 prefecture-level cities indicate that Nantong, Huai’an, Yancheng, Suzhou, Nanjing, and Wuxi can achieve carbon peak before 2030 in all four scenarios. Changzhou, Xuzhou, Yangzhou, Taizhou, Suqian, Lianyungang, and Zhenjiang are all able to achieve carbon peak between 2025 and 2029 under the low-growth, slow-consumption scenario (P2G2E1) and low-growth, fast-consumption scenario (P2G2E2), but they cannot achieve carbon peak before 2030 under the high-growth, slow-consumption scenario (P1G1E1) and high-growth, fast-consumption scenario (P1G1E2). Finally, based on the carbon peak prediction model, the prefecture-level cities are classified, and differentiated carbon peak implementation paths for different types of prefecture-level cities are proposed.

As one of the most important sources of carbon emissions, the construction industry consumes approximately 30% to 40% of global energy and emits about 30% of global greenhouse gases. Therefore, low-carbon emission reduction in the construction industry is an important means for China to achieve its “3060” strategic goals. In this context, prefabricated buildings have become a development direction for the transformation and upgrading of the construction industry due to their green, low-carbon, and efficient characteristics. Jiangsu Province in China has taken the lead in promoting the application of “three slabs”. Currently, the precast concrete floor slabs in the province mainly use two types: laminated slabs and prestressed hollow slabs. This article takes three types of slab systems (laminated slabs, prestressed hollow slabs, cast in-site slabs) as the research objects, compares and analyzes the construction process of the three in the materialization stage, establishes a calculation model for carbon emissions and comprehensive costs in the materialization stages, and conducts a comparative analysis of carbon emissions and economics from both environmental and economic perspectives. Research has shown that during the materialization stage, cast in-site slabs have the highest carbon emissions per unit area, with an increase of approximately 71.3% and 74.3% compared to laminated slabs and prestressed hollow slabs, respectively. The highest construction and installation cost per unit area is also for cast in-site slabs, which are increased by about 113.8% and 64.9%, respectively, compared to laminated slabs and prestressed hollow slabs. Among them, material costs are the most significant factor affecting construction and installation costs. The comprehensive cost per unit area of cast in-site slabs is much higher than that of laminated slabs and prestressed hollow slabs, with the construction and installation costs being the most important factors affecting the comprehensive cost. Therefore, compared with cast in-site slabs, laminated slabs and prestressed hollow slabs have significant advantages in carbon emissions and economics and thus have practical significance for carbon reduction in the construction industry and are worth promoting and further developing.