1. Introduction
With the decrease in natural resources and the global variation in climate, the construction industry, as a significant factor impacting the global environment, faces many challenges. In response, the engineering field has developed numerous new technologies [
1]. Advancements, including high-performance novel structures [
2,
3] and digital design methods [
4,
5], are being extensively researched to achieve the goal of sustainable development. Furthermore, the construction industry is responsible for about 30–40% of total carbon emissions across all industries [
6]. Therefore, the calculation and analysis of carbon emissions of buildings is crucial for achieving energy conservation, emission reduction, and sustainability.
Currently, the development and promotion of super high-rise building projects have become key measures to alleviate the land shortage problem caused by the rapid population growth in urban communities [
7]. These projects are effective in optimizing architectural functions and increasing property value [
8]. The super high-rise steel structure system has gradually become the preferred structural option, attributed to its superior structural performance, high degree of prefabrication, and high construction efficiency. Khan et al. [
9] reviewed the development and potential of super high-rise prefabricated steel structures, while Gong et al. [
8] elaborated on the development process of engineering technology for super high-rise buildings in China. In particular, RC core wall-steel frame structures have emerged as the mainstream structural form due to their structural stability and scalability. Many studies have been conducted focusing on these structures from aspects including health monitoring [
10], structural components [
11], and mechanical response [
12]. Additionally, the parallel construction mode of the steel frame and RC core tube significantly accelerates the construction progress and effectively shortens the construction period.
However, due to their huge material usage and complex energy requirements, super high-rise buildings often entail higher energy consumption and carbon emissions [
13]. Therefore, from the perspective of long-term sustainable development, reducing the energy consumption and greenhouse gas emissions of super high-rise buildings is crucial. Measures related to different elements throughout the life cycle of the building need to be utilized to achieve energy conservation and emission reduction. Significant progress has been made in the research on green design for high-rise and super high-rise buildings. Some advancements have improved the energy efficiency [
14,
15] of super high-rise buildings through energy-saving designs [
16], including utilizing adaptive building skins [
17,
18,
19]. Tabadkani et al. [
16] developed and optimized an origami-based adaptive solar façade system utilizing parametric design tools aiming at enhancing comfort and sustainability. Progress has also been made by achieving sustainability goals through the optimization of structural designs [
20,
21]. For instance, Choi et al. [
22] proposed a multi-objective green design model aimed at minimizing construction costs and reducing carbon emissions. Gan et al. [
23] conducted comparative analyses of carbon emissions in high-rise buildings under different design parameters, including building materials, recycled components, structural forms, and building height. Choi et al. [
24] proposed an optimal design method with a genetic algorithm to reduce cost and CO
2 emissions from structural materials in high-rise buildings. The method was successfully applied to a 35-story building.
In addition to the overall control during the building design phase, some works have explored the potential to reduce carbon emission of building materials [
25,
26] and components [
27,
28]. For instance, Tae et al. [
29] evaluated the environmental performance of high-strength concrete as an environmental load-reducing material in super high-rise buildings. By converting the compressive strength of concrete in existing buildings to 40 MPa high-strength concrete, they have achieved a reduction in the quantity of concrete and steel, simultaneously enhancing the lifespan of the building. Oh et al. [
30] proposed an optimal design model for the low-carbon construction of reinforced concrete two-way slabs. Compared to traditional design methods, this optimal sustainable design approach considers various design scenarios, resulting in a reduction in carbon emissions for office and commercial buildings.
Building information modeling (BIM) is a digital modeling technique that centers on the fundamental elements of building components, integrating material visual characteristics, physical properties, and geometric data to achieve a detailed representation of data at various levels [
31]. Several studies have been conducted for further enhancement of the utilization of BIM in practical engineering to achieve more efficient smart construction settlements [
32]. For instance, Hong et al. [
33] analyze the key factors influencing the acceptance of mobile BIM technology among construction practitioners and propose a model for promoting mobile BIM usage based on a survey and structural equation modeling. In addition, BIM has been proven to be efficient in sustainability analyses and management [
34]. For instance, Sun et al. [
35] conducted an assessment of CO
2 emissions during the tunnel construction process based on BIM. Yevu et al. [
36] conducted a systematic review on the integration of BIM and prefabrication to advance low-carbon efforts in building delivery. Many scholars have integrated BIM technology to achieve life cycle assessment (LCA) of carbon emissions [
37,
38]. Utilizing BIM models as data carriers significantly enhances the reuse rate of building information and achieves the assessment of environmental impacts throughout the lifecycle of buildings [
39,
40]. For instance, Cheng et al. [
41] combined the theory of LCA with BIM to propose a green building assessment method, leveraging the rich engineering information provided by BIM. Ding et al. [
42] proposed a carbon emission measurement system based on BIM focusing on prefabricated residential buildings. Cang et al. [
43] proposed a calculation method based on BIM utilizing “building element” as the basic unit suitable to provide design feedback during the schematic design stage. These BIM-enabled LCA carbon emission analyses encompass various stages of building development and different building types. Additionally, some studies have integrated BIM with GIS [
44,
45] and machine learning [
46,
47] technologies to enhance the performance of the analysis framework. In particular, Liu et al. [
48] integrated BIM with various intelligent algorithms to optimize design parameters with a focus on sustainability.
However, previous studies have primarily concentrated on the environmental impacts of smaller-scale or conventional high-rise structures, lacking the specificity and detail needed for super high-rise buildings with unique structural systems. The related analysis and evaluation systems focusing on super high-rise buildings with RC core wall-steel frame structures are still underdeveloped and are mostly limited to qualitative analysis. Additionally, the emission reduction strategies for super high-rise buildings during the materialization stage are currently not well developed. Our aim is to offer a comprehensive quantitative model that specifically addresses these gaps. Consequently, this work specifically focuses on the carbon emission analysis of super high-rise buildings with RC core wall-steel frame structures. By examining the energy consumption and carbon emission characteristics of super high-rise buildings, key influencing factors are identified. Combining these insights with real-world case studies, a carbon emission analysis model based on BIM-enabled LCA focusing on the materialization stage and the waste recycling stage is constructed. Additionally, a comparative analysis of carbon emissions under different construction strategies is conducted, summarizing and outlining low-carbon strategies for these buildings.
4. Discussion
This chapter discusses low-carbon construction strategies for super high-rise buildings with concrete core wall-steel frame structures based on the results presented above. According to the findings, carbon emissions generated during the production stage significantly dominate emissions throughout the entire materialization stage. Therefore, formulating targeted strategies to reduce carbon emissions during material production is particularly critical. Steel offers good seismic performance and low weight but has a high carbon emission factor, as shown in
Table A1. In contrast, concrete features strong plasticity and can be adapted to various structural systems, with a lower carbon emission factor but a higher weight. The hybrid structure of steel and concrete can combine the advantages of both materials, thus reducing carbon emissions. Furthermore, utilizing 3R (reducible, recyclable, reusable) materials can decrease the frequency of resource extraction and reduce carbon emissions during the production process of building materials.
In addition, an optimized manufacturing process of building materials not only directly reduces carbon emissions but also enhances the strength and corrosion resistance of materials. This improvement in material efficiency decreases the amount of building materials needed, thereby indirectly reducing the carbon emissions associated with buildings. Based on the results in
Section 3.3, incorporating fly ash alone in concrete and adding composite mineral admixtures results in carbon emission reduction rates of 5.9% and 11.7%, respectively. For steel, adopting the EAF results in a carbon emission reduction rate of 23.8%. When 30% of recycled scrap steel is utilized in the BF-BOF process, the carbon emission reduction rate is 22.2%. Moreover, when the EAF process utilizes 80% recycled scrap steel, the carbon emission reduction reaches 56.4%. Compared to different admixtures in concrete, optimizing the steel manufacturing process has a more significant effect in reducing carbon emissions in super high-rise buildings.
According to Equation (3), the carbon emissions during the transportation stage are influenced by the distance from the production site to the construction site, the weight of the building materials being transported, and the mode of transportation. Therefore, strategies for reducing carbon emissions at this stage include prioritizing locally sourced building materials to reduce transportation distances and lower carbon emissions. In addition, choosing transportation methods with lower carbon emission factors, including opting for gasoline-fueled vehicles over diesel-fueled ones for road transport, can also contribute to the reduction in carbon emissions.
During the construction stage, carbon emissions mainly originate from construction tools, including formwork, energy consumption of machinery, and related emissions from labor activities. Therefore, adopting prefabricated construction methods and selecting solutions with higher prefabrication rates can effectively reduce the utilization of formwork and improve construction efficiency. Additionally, introducing green construction technologies and prioritizing machinery with higher energy efficiency helps minimize energy consumption during equipment operation. Lastly, enhancing green construction management through optimized processes not only boosts construction efficiency but also reduces material waste throughout the construction process.
Regarding the waste recycling stage, the method of handling discarded materials is crucial. Implementing optimized demolition plans enhances the recycling rate of discarded materials and reduces pollution generated during demolition. Moreover, expanding methods for reusing discarded materials, including employing them for office area partitions, further enhances sustainable practices.