Research

18 pages, 2093 KiB

Open AccessArticle

Research on Influencing Factors of Residential Building Carbon Emissions and Carbon Peak: A Case of Henan Province in China

by Xin Yang, Yifei Sima, Yabo Lv and Mingwei Li

Sustainability 2023, 15(13), 10243; https://doi.org/10.3390/su151310243 - 28 Jun 2023

Cited by 5 | Viewed by 1287

Abstract

Buildings are considered to have significant emission reduction potential. Residential building carbon emissions, as the most significant type of building-related carbon emissions, represent a crucial factor in achieving both carbon peak and carbon neutrality targets for China. Based on carbon emission data from [...] Read more.

Buildings are considered to have significant emission reduction potential. Residential building carbon emissions, as the most significant type of building-related carbon emissions, represent a crucial factor in achieving both carbon peak and carbon neutrality targets for China. Based on carbon emission data from Henan Province, a large province located in central China, between 2010 and 2020, this study employed the Kaya-LMDI decomposition method to analyze seven driving factors of carbon emission evolution, encompassing energy, population, and income, and assessed the historical reduction in CO₂ emissions from residential buildings. Then, by integrating Kaya identity static analysis with Monte Carlo dynamic simulation, various scenarios were established to infer the future evolution trend, peak time, and potential for carbon emission reduction in residential buildings. The analysis results are as follows: (1) The carbon emissions of residential buildings in Henan exhibited a rising trend from 2010 to 2020, albeit with a decelerating growth rate. (2) Per capita household disposable income is the main driving factor for the increase in carbon emissions, but the household housing purchase index inhibits most of the growth of carbon emissions for the residential buildings in Henan, with the total carbon emission reduction of residential buildings reaches 106.42 million tons of CO₂ during the research period. (3) During the period from 2020 to 2050, residential buildings in Henan Province will exhibit an “inverted U-shaped” trend in carbon emissions under the three static scenarios. The base scenario predicts that carbon emissions will reach their peak of 131.66 million tons in 2036, while the low-carbon scenario forecasts a peak of 998.8 million tons in 2030 and the high-carbon scenario projects a peak of 138.65 million tonnes in 2041. (4) Under the dynamic simulation scenario, it is anticipated that residential buildings in Henan Province will reach their carbon peak in 2036 ± 3 years, with a corresponding carbon emission of 155.34 million tons. This study can serve as a valuable reference for the future development of low-carbon pathways within the building sector. Full article

(This article belongs to the Special Issue Approaching Carbon Neutrality: Low-Carbon Solutions to Urban Regeneration and Green Economy)

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34 pages, 5173 KiB

Open AccessArticle

Volumetric Modular Construction Risks: A Comprehensive Review and Digital-Technology-Coupled Circular Mitigation Strategies

by Ayaz Ahmad Khan, Rongrong Yu, Tingting Liu, Ning Gu and James Walsh

Sustainability 2023, 15(8), 7019; https://doi.org/10.3390/su15087019 - 21 Apr 2023

Cited by 3 | Viewed by 3123

Abstract

Volumetric modular construction (VMC) has considerable benefits in providing better cost, time, quality, productivity, and sustainability performance. However, the adoption is low, owing to various associated risks. This study aims to identify VMC critical risk factors (CRFs) in project stages and project attributes [...] Read more.

Volumetric modular construction (VMC) has considerable benefits in providing better cost, time, quality, productivity, and sustainability performance. However, the adoption is low, owing to various associated risks. This study aims to identify VMC critical risk factors (CRFs) in project stages and project attributes by conducting a systematic literature review of 91 articles. In the project stages, 31 CRFs were identified based on frequency analyses, and divided into four stages: design and planning, offsite manufacturing, transportation and logistics, and onsite assembly. The project attribute risks were divided into the following categories: implementation and schedule, supply chain and financial, safety and ergonomic, and civil and structural. Overall, design and planning risks were critical, as they are crucial in maintaining the project’s upstream and downstream flow. Finally, the study proposed a mitigation framework for using digital technology-based circular strategies to overcome VMC risks. The framework includes disruptive and emergent digital technologies aiming to mitigate risks in VMC, keeping circularity in action. In terms of theoretical contributions, this research delivers a CRF register and categorical division for professionals to better understand the landscape of VMC risks. In terms of practical contributions, the study guides the practitioners towards strategies to overcome the pertinent risks. Full article

(This article belongs to the Special Issue Approaching Carbon Neutrality: Low-Carbon Solutions to Urban Regeneration and Green Economy)

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15 pages, 2355 KiB

Open AccessArticle

A Comparative Study on the Crystalline and Surface Properties of Carbonized Mesoporous Coconut Shell Chars

by Zaib Un Nisa, Lee Kean Chuan, Beh Hoe Guan, Faiz Ahmad and Saba Ayub

Sustainability 2023, 15(8), 6464; https://doi.org/10.3390/su15086464 - 11 Apr 2023

Cited by 3 | Viewed by 1773

Abstract

In the present work, the facile thermal decomposition of raw coconut shells was carried out for the exploitation of the role of inert gas in the carbonization process and its role in determining the morphology, crystallographic parameters, and surface area of biochar before [...] Read more.

In the present work, the facile thermal decomposition of raw coconut shells was carried out for the exploitation of the role of inert gas in the carbonization process and its role in determining the morphology, crystallographic parameters, and surface area of biochar before activation. The comparative investigation of mesoporous carbonized products synthesized with the muffle and tube furnace was carried out at a similar temperature and an assessment was made with a commercial carbon. The focus of the work was aimed at the interpretation of surface morphology, elemental identification, phase composition, interplanar spacing, full-width half maximum, crystallite size, lateral size, number of layers, dislocation density, microstrain, packing density, crystallinity index, and the specific surface area of the product obtained from two different approaches. It was revealed that the carbonized coconut shell chars obtained from the tube furnace have better characteristics to be activated further for carbon black synthesis. So, the flow of inert gas in a tube furnace is demonstrated to have a key role in improving the attributes of coconut shell chars. Full article

(This article belongs to the Special Issue Approaching Carbon Neutrality: Low-Carbon Solutions to Urban Regeneration and Green Economy)

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21 pages, 12918 KiB

Open AccessArticle

Analysis of a Simplified Model of a Rigid Rocking Block on Winkler Foundation

by Dongyi He, Peizhen Li and Zhen Zhang

Sustainability 2023, 15(6), 5095; https://doi.org/10.3390/su15065095 - 13 Mar 2023

Viewed by 1083

Abstract

It has been observed from previous large earthquakes that weakening the structural foundation can reduce the damage of the structure itself by allowing a rocking motion to release the seismic energy, and this seismic design philosophy is gradually applied to new constructions. In [...] Read more.

It has been observed from previous large earthquakes that weakening the structural foundation can reduce the damage of the structure itself by allowing a rocking motion to release the seismic energy, and this seismic design philosophy is gradually applied to new constructions. In this paper, a simplified model of the motion process of a rigid rocking block is proposed, the rocking motion equation of rigid rocking block is derived, and the parameter analysis is carried out. It was found that the height–width ratio and damping have a great impact on the rocking response of the structure. On this basis, combined with the Winkler foundation model, the equation of motion of the rigid rocking block considering the flexibility of the foundation is established. Through the analysis of an example, it is found that damping plays an important role in the overturning resistance of high-rise buildings and the soil elastic coefficient has a greater impact on the higher structure. Full article

(This article belongs to the Special Issue Approaching Carbon Neutrality: Low-Carbon Solutions to Urban Regeneration and Green Economy)

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18 pages, 2987 KiB

Open AccessArticle

An Analysis of Soil Erosion on Construction Sites in Megacities Using Analytic Hierarchy Process

by Hongliang Tang, Pengkun Shi and Xiaoli Fu

Sustainability 2023, 15(2), 1325; https://doi.org/10.3390/su15021325 - 10 Jan 2023

Cited by 3 | Viewed by 1542

Abstract

The highly intensive construction activities in the process of urbanization have led to the risk of soil loss, which is due to the disturbance of urbanization on the soil; this makes the soil more vulnerable to erosion by rain and other factors, thus [...] Read more.

The highly intensive construction activities in the process of urbanization have led to the risk of soil loss, which is due to the disturbance of urbanization on the soil; this makes the soil more vulnerable to erosion by rain and other factors, thus causing soil loss to the urban drainage pipe network or the river channels around the city. This process is affected by both natural and human factors. Based on engineering experience and existing research, 13 influencing factors were identified and classified into four dimensions: Natural Conditions (NC), Construction Activities (CA), Conservation Measures (CM) and Management Measures (MM). Fifteen experts from Shanghai, Guangzhou and Zhengzhou, three main cities in China, were invited to assess the weight of each influencing factor through pairwise comparison. Based on the analytic hierarchy process, the soil erosion risk evaluation model of construction sites in megacities was established, and the weight of each influencing factor was determined. According to the weights, the weighted summation method can be used to calculate the comprehensive scores of these sites and the soil erosion risks of the construction sites can be ranked according to the comprehensive scores for multiple construction sites. The analysis of the model shows that MM is the most important factor, and improving the management level is the key measure to control the soil erosion of construction site in megacities. In addition, in the four dimensions, the results of the weight of each influencing factor in the NC dimension are quite different; this is due to the different cities where the experts are from, indicating that the natural conditions of the location will affect empirical judgment. By inviting many experts to evaluate, the deviation in judgment results, caused by differences in natural conditions, can be reduced. Full article

(This article belongs to the Special Issue Approaching Carbon Neutrality: Low-Carbon Solutions to Urban Regeneration and Green Economy)

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23 pages, 7161 KiB

Open AccessArticle

Research on Sustainable Development of the Regional Construction Industry Based on Entropy Theory

by Zhiwu Zhou, Julián Alcalá and Víctor Yepes

Sustainability 2022, 14(24), 16645; https://doi.org/10.3390/su142416645 - 12 Dec 2022

Viewed by 1467

Abstract

Human beings are now facing the increasingly urgent problem of global ecological environment pollution. To verify the scientific nature of environmental governance by governments of various countries, researchers need to provide a scientific basis and practical support for governments to adjust and formulate [...] Read more.

Human beings are now facing the increasingly urgent problem of global ecological environment pollution. To verify the scientific nature of environmental governance by governments of various countries, researchers need to provide a scientific basis and practical support for governments to adjust and formulate new policies and regulatory measures at any time through data analysis. This paper applies visual literature, aggregate analysis, engineering data programming, advanced mathematical science algorithms, and innovation entropy theory, and through this study obtains sustainable impact data from eight Chinese provinces in the 21st century, including environmental, economic, and social impacts. The results show that China’s sustainable data should grow from 2021 to about 2044. After 2045, it will be stable, and there will be negative growth in a short period. The overall life cycle assessment (LCA) and social impact assessment (SIA) continue to remain in the positive range. There will be no negative growth in aggregate data and zero or negative emissions before 2108. The final research data are accurately presented in the form of annual emissions, which provide a scientific and theoretical basis for the government to formulate medium- and long-term ecological regulations and plans. Full article

(This article belongs to the Special Issue Approaching Carbon Neutrality: Low-Carbon Solutions to Urban Regeneration and Green Economy)

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18 pages, 764 KiB

Open AccessArticle

Exploring the Critical Success Factors of Value Management Implementation for Sustainable Residential Building Project: A Stationary Analysis Approach

by Ahmed Farouk Kineber, Md Sharif Uddin and Alaa Fouad Momena

Sustainability 2022, 14(23), 16215; https://doi.org/10.3390/su142316215 - 05 Dec 2022

Cited by 4 | Viewed by 1898

Abstract

During the past two decades, value management (VM), has developed into a recognized construction practice. However, the methods and activities associated with VM adopt informal approaches in developing countries. This study aims to explore the critical success factors (CSFs) of VM implementation. Consequently, [...] Read more.

During the past two decades, value management (VM), has developed into a recognized construction practice. However, the methods and activities associated with VM adopt informal approaches in developing countries. This study aims to explore the critical success factors (CSFs) of VM implementation. Consequently, VM CSFs were investigated from the previous literature and further categorized over a semi-structured interview. The importance of these CSFs investigated by 335 structured questionnaires completed by residential building professionals. Subsequently, the exploratory study using the exploratory Pearson correlation of the VM CSFs was employed to validate the categorization resulting from a semi-structured interview and pilot study phases. Based on the validation results, the VM CSFs may be divided into four dimensions: culture and environment, workshop dynamics, stakeholder and knowledge, and standardization. Through important relative index (RII) analysis, the essential CSFs creates a VM team from a variety of disciplines, VM knowledge, experience of participants, and professional experience of the different participants’ diverse disciplines. In addition, this research used a stationary analytic strategy to evaluate the degree to which VM critical success factors (CSFs) have been incorporated into residential construction projects in Egypt. The results revealed that “establishing the roles and purposes of various professions” was the stationary success factor for adopting VM. This research establishes a road map for successful VM implementation via VM CSFs in Egypt and other underdeveloped nations. Stakeholders in the residential construction sector would benefit from this study by learning more about VM CSFs and how they may be used to increase the value of their projects. Full article

(This article belongs to the Special Issue Approaching Carbon Neutrality: Low-Carbon Solutions to Urban Regeneration and Green Economy)

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24 pages, 4755 KiB

Open AccessArticle

Reuse and Retrofitting Strategies for a Net Zero Carbon Building in Milan: An Analytic Evaluation

by Daniela Besana and Davide Tirelli

Sustainability 2022, 14(23), 16115; https://doi.org/10.3390/su142316115 - 02 Dec 2022

Cited by 9 | Viewed by 3176

Abstract

The building sector accounts for 38% of carbon emissions, the principal cause of climate change. To meet the targets set by the Paris Agreement, including zero net emissions by 2050, it is necessary that governments develop a culture of sustainability. Whole Life Carbon [...] Read more.

The building sector accounts for 38% of carbon emissions, the principal cause of climate change. To meet the targets set by the Paris Agreement, including zero net emissions by 2050, it is necessary that governments develop a culture of sustainability. Whole Life Carbon Assessment of a building, comprehensive of operational and embodied carbon (EC), is described by EN15978:2011. Net Zero Carbon Buildings (NZCB) achieve a balance of zero emissions during their life cycle, promoting both reduction and compensation by adopting many strategies (e.g., reuse of existing structures, design for adaptability and disassembly, circular economy principles). Choosing bio-based materials is also helpful to compensate for EC, thanks to the biogenic carbon stored during their growth. The aim of this research is to find out which strategies are relevant to meet NZCB target, in order to apply them to a case study of reuse of an abandoned building in Milan, highlighting the design process. Material quantities were extracted from the BIM model and imported in OneClick LCA to assess embodied carbon emissions (A1–A5 modules, material production and supply, transport, construction). The final design stage achieved a reduction of 91% in EC compared to a standard new construction, while the bio-based materials compensated for the rest. Further research can improve the Environmental Product Declaration (EPD) of materials and assess the entire building life cycle. Full article

(This article belongs to the Special Issue Approaching Carbon Neutrality: Low-Carbon Solutions to Urban Regeneration and Green Economy)

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19 pages, 946 KiB

Open AccessArticle

Exploring the Sustainable Delivery of Building Projects in Developing Countries: A PLS-SEM Approach

by Ahmed Farouk Kineber and Mohammed Magdy Hamed

Sustainability 2022, 14(22), 15460; https://doi.org/10.3390/su142215460 - 21 Nov 2022

Cited by 6 | Viewed by 1612

Abstract

Sustainable building approaches should be included at every level of the development process for maximum benefit without jeopardising the structure’s intended usage. However, researchers have paid less attention to how they may be applied to developing nations. This study aims to investigate the [...] Read more.

Sustainable building approaches should be included at every level of the development process for maximum benefit without jeopardising the structure’s intended usage. However, researchers have paid less attention to how they may be applied to developing nations. This study aims to investigate the numerous determinants of sustainable delivery in the construction industries of developing nations. For this to happen, existing literature was used to inform the development of a closed-ended questionnaire. Consequently, 95 structured questionnaires by building professionals investigated the importance of these factors. As a result, the factor’s structure was determined and confirmed using the study’s partial least square structural equation modelling (PLS-SEM) approach, which was utilised to investigate the connections between these factors. According to the PLS-SEM analysis, the factors most strongly influencing sustainable delivery are those associated with the preparation, followed by evaluation and use factors, respectively. As a result of this research, authorities in Egypt’s building sector will have a road map for implementing sustainability principles to reduce building costs, boost the local ecosystem, and strengthen social cohesion. Full article

(This article belongs to the Special Issue Approaching Carbon Neutrality: Low-Carbon Solutions to Urban Regeneration and Green Economy)

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17 pages, 7411 KiB

Open AccessArticle

The Effect of Recycled Sand on the Tensile Properties of Engineered Cementitious Composites

by Zhifu Dong, Yan Tan, Xiangru Jian, Jiangtao Yu and Kequan Yu

Sustainability 2022, 14(20), 13530; https://doi.org/10.3390/su142013530 - 19 Oct 2022

Cited by 1 | Viewed by 1189

Abstract

This research aims to investigate the feasibility of replacing natural sand (NS) with recycled sand (RS) to enhance the mechanical property of engineered cementitious composites (ECC). For a comparative study, ECCs incorporating natural sands (NS) and recycled sands with different sieve sizes were [...] Read more.

This research aims to investigate the feasibility of replacing natural sand (NS) with recycled sand (RS) to enhance the mechanical property of engineered cementitious composites (ECC). For a comparative study, ECCs incorporating natural sands (NS) and recycled sands with different sieve sizes were taken as experimental subjects. The results demonstrated that RS-ECC possessed better tensile properties featuring saturated cracks and superior strain-hardening behavior than that of NS-ECC. The highest tensile strain capacity of RS-ECC was up to 7%. Meanwhile, the compressive and flexural strengths of RS-ECC were over 50 and 20 MPa. The pseudo-strain-hardening (PSH) index of the RS-ECC-20 grid and RS-ECC-12 grid were 141 and 201, which increased by 46% and 70% than that of NS-ECC. Furthermore, the thicker weak ITZ and comparatively aggregate/ITZ ratio were found in the RE-ECC by a microstructure test, which revealed and explained the mechanism for the lower matrix fracture toughness of RS-ECC. Full article

(This article belongs to the Special Issue Approaching Carbon Neutrality: Low-Carbon Solutions to Urban Regeneration and Green Economy)

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21 pages, 6125 KiB

Open AccessArticle

Feasibility of using Waste Brine/Seawater and Sea Sand for the Production of Concrete: An Experimental Investigation from Mechanical Properties and Durability Perspectives

by Yongxiang Cui, Jiafei Jiang, Tengfei Fu and Sifeng Liu

Sustainability 2022, 14(20), 13340; https://doi.org/10.3390/su142013340 - 17 Oct 2022

Cited by 6 | Viewed by 2144

Abstract

The anti-corrosion property of fiber reinforced polymer (FRP) makes the concrete produced with marine wastes (waste brine after desalination) and resources (seawater and sea sand) a promising green structural material which can be a sustainable solution to fresh water and river sand scarcity [...] Read more.

The anti-corrosion property of fiber reinforced polymer (FRP) makes the concrete produced with marine wastes (waste brine after desalination) and resources (seawater and sea sand) a promising green structural material which can be a sustainable solution to fresh water and river sand scarcity in marine and offshore construction. To evaluate the feasibility of using waste and marine resources in concrete, this study investigated the mechanical properties and durability of brine-sea sand concrete (BSC) and seawater-sea sand concrete (SSC) with three different water-to-cement ratios and compared them to the corresponding ordinary concrete (OC). The results demonstrated that the increased salinity had a minor effect on the 28-day compressive strength, but a significant effect on the large-size capillary pore structure. The semi-quantitative analysis of the concrete phase based on the X-ray diffraction (XRD) and thermogravimetric analysis (TGA) revealed that BSC and SSC had larger mass fractions of the amorphous phase (mainly C-S-H), ettringite and gypsum during hydration. At last, the comprehensive performance of three different concrete mixtures was evaluated by five indexes (workability, alkali environment, compressive strength, carbonization resistance, and sulfate resistance). The results show that it is feasible to use brine/seawater and sea sand to replace freshwater and river sand for marine structural concrete reinforced with FRP. Full article

(This article belongs to the Special Issue Approaching Carbon Neutrality: Low-Carbon Solutions to Urban Regeneration and Green Economy)

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11 pages, 3845 KiB

Open AccessArticle

Experimental Investigation on Vibration Control of a Suspended Particle-Tuned Liquid Damper

by Zheng Lu, Mengyao Zhou and Hongmei Ren

Sustainability 2022, 14(20), 13085; https://doi.org/10.3390/su142013085 - 12 Oct 2022

Cited by 1 | Viewed by 1144

Abstract

The particle-tuned liquid damper (PTLD) can combine the functions of baffles and energy-dissipating materials, such as highly viscous liquids, by integrating the particle dampers into a conventional tuned liquid damper (TLD). However, the particles distributed only at the bottom of the container cannot [...] Read more.

The particle-tuned liquid damper (PTLD) can combine the functions of baffles and energy-dissipating materials, such as highly viscous liquids, by integrating the particle dampers into a conventional tuned liquid damper (TLD). However, the particles distributed only at the bottom of the container cannot drive the motion of water in the middle layer to function effectively. Therefore, a suspended particle-tuned liquid damper (SPTLD) is proposed in this study and its effectiveness and reliability are examined compared with the conventional TLD through shaking table tests. Based on the experimental results, a parametric analysis of the SPTLD is further conducted to investigate the damping mechanism of the SPTLD, including the number of particles, the excitations with various amplitudes, and the use of suspended versus floating particles in liquid. The test results revealed that SPTLD successfully controlled the structural acceleration responses under seismic excitations with good reliability; the peak acceleration response was reduced by 67.4% and the RMS value was reduced by 75.9%. In the SPTLD, the particles filled in the container can drive more liquid to effectively participate in the sloshing motion, and the superimposed damping effects involving collisions and the energy-dissipation mechanisms of buoyancy and hydraulic resistance in the SPTLD lead to an improvement in the vibration control performance. Furthermore, the comparison of SPTLD and the floating particle-tuned liquid damper (FPTLD) demonstrates the better availability of SPTLD in practical applications, especially for some slender structures with limited plane space on the top floor. Full article

(This article belongs to the Special Issue Approaching Carbon Neutrality: Low-Carbon Solutions to Urban Regeneration and Green Economy)

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18 pages, 4925 KiB

Open AccessArticle

The Suburbanization and Revitalization of Industrial Land in Shanghai, China

by Jihong Li, Kaiming Li and Rongxu Qiu

Sustainability 2022, 14(12), 7062; https://doi.org/10.3390/su14127062 - 09 Jun 2022

Cited by 2 | Viewed by 1960

Abstract

Land use efficiency is one of the critical indicators of sustainable development. Increasing land use efficiency can help build a more compact urban form and reduce the urban footprint. Industrial development is often considered a major driving force of urban land use expansion [...] Read more.

Land use efficiency is one of the critical indicators of sustainable development. Increasing land use efficiency can help build a more compact urban form and reduce the urban footprint. Industrial development is often considered a major driving force of urban land use expansion and use change. Both industrial development and urban land use change are constrained and facilitated by urban planning and management, constantly shaping the spatial trajectory of urban transformation. Taking the suburbanization and revitalization of industrial land uses in Shanghai as a case study, this research uses thematical analysis and geospatial data change detection methods to investigate how the evolution of industrial spatial structure leads to urban land use growth, and how urban planning and governance reconfigure the industrial spatial structure of a city through revitalization. This study found that the unplanned suburbanization of industrial land use brought about significant residential and commercial land use expansion. The city was able to consolidate its industrial land uses by adopting the designated industrial blocks strategy to curb the sprawl of industrial land use and enhance land use efficiency. With the transformation of industry structure, the city achieved great success in transforming underutilized industrial land in the city’s central area and consolidating scattered industrial land into industrial blocks in the city’s suburban areas. Full article

(This article belongs to the Special Issue Approaching Carbon Neutrality: Low-Carbon Solutions to Urban Regeneration and Green Economy)

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17 pages, 5391 KiB

Open AccessArticle

Simulation of Leakage Characteristics of Combined Seal Structure under Rotational Conditions

by Bin Zhang, Jin Li, Xiaoli Fu and Shenglin Yan

Sustainability 2022, 14(6), 3648; https://doi.org/10.3390/su14063648 - 20 Mar 2022

Cited by 1 | Viewed by 1587

Abstract

In order to reduce fluid leakage and improve the working efficiency of rotational machinery, a three-dimensional (3D) model of combined seal structure (CSS) was established to study the influence of pressure ratio (π, the ratio of the leakage port pressure to [...] Read more.

In order to reduce fluid leakage and improve the working efficiency of rotational machinery, a three-dimensional (3D) model of combined seal structure (CSS) was established to study the influence of pressure ratio (π, the ratio of the leakage port pressure to the outlet pressure) and rotational speed (n) on the leakage characteristics of CSS with a traditional labyrinth seal structure (LSS) and pocket damping seal structure (PDS) under rotational conditions. Two turbulence models, the standard k-ε model and the SST k-ω model, were used for turbulence closure and the results of the standard k-ε model were found to be more accurate based on comparison with experimental results. The results revealed that under rotational condition, the leakage rates of LSS, CSS and PDS all decreased with the increase in π and n. Under the same axial length of seal structure and π of 0.5 and n of 6000 r/min, the leakage rate of CSS is approximately 8.56% less than LSS, and approximately 0.51% more than PDS. There is a critical value for the influence of n on the leakage rate. The critical n of CSS is close to that of LSS, about 1000 r/min, which is greater than the critical n of 500 r/min for PDS. Finally, the sealing mechanism of CSS was studied using a two-dimensional (2D) model, and was found that the jet structure has a greater influence on the sealing characteristics. Among them, when the ΔP (internal resistance of the device) is the same, the shape of the jet structure, the position of the guide tube and the nozzle radius have a greater impact on the leakage rate, and the shape and length of the extended section have a small effect on the leakage rate. Full article

(This article belongs to the Special Issue Approaching Carbon Neutrality: Low-Carbon Solutions to Urban Regeneration and Green Economy)

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15 pages, 3336 KiB

Open AccessArticle

Analytical Comparison of German Owner’s Budget Estimate and Chinese Contractor’s Bid: A Case Study for a Warehouse Building Project in China

by Gen Li and Rong Xu

Sustainability 2022, 14(2), 970; https://doi.org/10.3390/su14020970 - 15 Jan 2022

Cited by 1 | Viewed by 2536

Abstract

Nowadays, the need for scientific and modernized engineering cost management has been increasingly prominent. Hence, this study compared the differences of the quantities’ terms, the management philosophy, the related institutions (or specifications), and other factors in engineering cost management between China and Germany [...] Read more.

Nowadays, the need for scientific and modernized engineering cost management has been increasingly prominent. Hence, this study compared the differences of the quantities’ terms, the management philosophy, the related institutions (or specifications), and other factors in engineering cost management between China and Germany accompanied by a case study for a warehouse building project in China. There are two main parts. Firstly, according to the literature research, the comparative analysis was conducted on the engineering cost-control mode, the list of bills of quantities, and other parameters between China and Germany. On the basis of this, the “differences” between China and Germany especially in the bidding process were further studied with the empirical analysis of engineering cases, which is a supplementary argument to the theoretical analysis. Finally, several related suggestions were put forward, including proposing a set of “universal” bills of quantities (which can be understood by Chinese enterprises and also accepted by foreign-funded enterprises), the establishment of the whole process, a dynamic and information-based project cost-management system, cultivation of talents with the advanced management concept, and the development of international engineering companies and project-management companies with core competitiveness. The conclusions are expected to provide some references for China’s construction industry to further expand the international market and to increase the influences in global markets. Full article

(This article belongs to the Special Issue Approaching Carbon Neutrality: Low-Carbon Solutions to Urban Regeneration and Green Economy)

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14 pages, 5386 KiB

Open AccessArticle

Experimental Study on Local Scour Depth around Monopile Foundation in Combined Waves and Current

by Junhan Li, Bin Zhang, Chao Shen, Xiaoli Fu and Weichao Li

Sustainability 2021, 13(24), 13614; https://doi.org/10.3390/su132413614 - 09 Dec 2021

Cited by 10 | Viewed by 2251

Abstract

Local scour is one of the key factors that cause the collapse of structures. To avoid structure failures and economic losses in water, it is usually essential to predict the equilibrium scour depth of the foundation. In this study, several design models which [...] Read more.

Local scour is one of the key factors that cause the collapse of structures. To avoid structure failures and economic losses in water, it is usually essential to predict the equilibrium scour depth of the foundation. In this study, several design models which were presented to predict the equilibrium scour depth either under steady clear water conditions and combined waves and current conditions were recommended. These models from China, the United States and Norway were analyzed and compared through experiments. Moreover, flume tests for monopile foundation embedded in sand under different flow conditions were carried out to observe the process and gauge the maximum depth around the pile. Based on this study, for predicting the equilibrium scour depth around bridge piers, the computational results of three design methods are all conservative, as expected. For the foundation of offshore structures in marine environment, most of the predicted scour depths by design methods are different from field data; in particular, the mean relative error with these design methods proposed may reach up to 966.5%, which may lead to underestimation of the problem, overdesign and consequently high construction cost. To further improve the ability of the scour prediction in a marine environment, data from flume tests and some field data from a previous study were used to derive the major factors of scour. Based on the dimensional analysis method, a new model to estimate the equilibrium scour depth induced by either current or waves is proposed. The mean relative error of the new formula is 49.1%, and it gives more accurate scour depth predictions than the existing methods. Full article

(This article belongs to the Special Issue Approaching Carbon Neutrality: Low-Carbon Solutions to Urban Regeneration and Green Economy)

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17 pages, 50852 KiB

Open AccessArticle

Mechanical Properties of High-Performance Hybrid Fibre-Reinforced Concrete at Elevated Temperatures

by Moawiah Mubarak, Raizal Saifulnaaz Muhammad Rashid, Mugahed Amran, Roman Fediuk, Nikolai Vatin and Sergey Klyuev

Sustainability 2021, 13(23), 13392; https://doi.org/10.3390/su132313392 - 03 Dec 2021

Cited by 15 | Viewed by 2964

Abstract

Deterioration of concrete’s integrity under elevated temperature requires an alteration in its composition to have better thermal stability. Fibre-reinforced concrete has shown significant improvements in concrete strength and this paper aimed to investigate the influence of steel (ST) and polypropylene (PP) fibres on [...] Read more.

Deterioration of concrete’s integrity under elevated temperature requires an alteration in its composition to have better thermal stability. Fibre-reinforced concrete has shown significant improvements in concrete strength and this paper aimed to investigate the influence of steel (ST) and polypropylene (PP) fibres on the behaviour of high-performance concrete (HPC) exposed to elevated temperatures. Six mixtures were prepared and cast by adding one or two types of polypropylene fibre (54 and 9 mm) at 0.25 or 0.5% and either singly or in a hybrid combination, along with a fixed volumetric content at 1% of five-dimensional hooked steel (5DH) fibres. At the age of 28 days, samples were heated to the targeted temperature of 800 °C and cooled down naturally to the laboratory temperature. Visual inspection, flexural, split tensile and compressive strengths were examined before and after the exposure to elevated temperatures. Results exhibited that the hybridization of long and short PP fibres, along with the ST fibres, has notably improved all residual mechanical properties of HPC and kept the integrity of concrete after exposure to elevated temperatures. In addition, PP fibres can significantly prevent spalling, but ST fibres were ineffective in mitigating explosive spalling in beams specimens. Full article

(This article belongs to the Special Issue Approaching Carbon Neutrality: Low-Carbon Solutions to Urban Regeneration and Green Economy)

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14 pages, 1465 KiB

Open AccessArticle

Study on Feasibility of Photovoltaic Power to Grid Parity in China Based on LCOE

by Zheng Lu, Yunfei Chen and Qiaoqiao Fan

Sustainability 2021, 13(22), 12762; https://doi.org/10.3390/su132212762 - 18 Nov 2021

Cited by 8 | Viewed by 1782

Abstract

Today, photovoltaic (PV) power generation accounts for a relatively small proportion of total power generation in China. If photovoltaic power can achieve grid parity, it can replace the original traditional thermal power generation, which has positive significance on the environment. The Levelized Cost [...] Read more.

Today, photovoltaic (PV) power generation accounts for a relatively small proportion of total power generation in China. If photovoltaic power can achieve grid parity, it can replace the original traditional thermal power generation, which has positive significance on the environment. The Levelized Cost of Energy (LCOE) is the main general economic indicator for the evaluation of power generation technology in the world. Based on the traditional LCOE evaluation model and considering the shortcomings of the previous LCOE evaluation models, the cost of photovoltaic power generation is refined in this paper. The cost of the taxation with calculating the depreciation, the loss, and the income of the Clean Development Mechanism (CDM) are taken into consideration. Hence, a more accurate and more comprehensive LCOE model is presented. Moreover, combined with other investment indicators, a photovoltaic power generation benefit model corresponding to the current development status is proposed. Taking a 3-MW distributed photovoltaic power station project in Nanjing as a case study, the sensitivity analysis of factors that affect the benefit of photovoltaic power generation is carried out to further explore the feasibility of photovoltaic power to grid parity. Full article

(This article belongs to the Special Issue Approaching Carbon Neutrality: Low-Carbon Solutions to Urban Regeneration and Green Economy)

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