The Reduction of CO2 Emissions by Application of High-Strength Reinforcing Bars to Three Different Structural Systems in South Korea

Construction Waste Reduction through Application of Different Structural Systems for the Slab in a Commercial Building: A South Korean Case

Construction waste generation along with the extensive consumption of natural resources has propelled researchers to investigate effective measures for minimising the waste. While several studies have shown that the structural design would be an influencing factor on the carbon dioxide emissions of a building, there is a lack of studies to corroborate the effect of different structural systems to generate waste during the construction stage. This article seeks to bridge some of the knowledge gaps regarding the waste generation from different structural systems during the construction phase in a building project in South Korea and demonstrate its potential for waste reduction. In this study, the amount of waste generation during the construction phase was calculated based on the quantities and the material loss rate of each building material to estimate the quantity of construction waste by the changes in the application of different structural systems for the slab of the studied model. The total waste generation during the construction phase of the different slab systems shows that the solid slab system produces the largest amount of construction waste, which is 101,361.385 kg. On the other hand, the void slab system generates 87,603.958 kg of the construction waste, which is the lowest amount among the four variables of this study. The additional purchasing costs due to the loss of construction materials indicate that the solid slab system would require 80,709.76 USD, which is the highest value of the four variables in this study. The void slab system would cost USD 50,054.12 for additional materials purchasing costs, which is approximately 38% lower than the solid slab system.

Status of Environmental Life Cycle Assessment (LCA): A Case Study of South Korea

The Life Cycle Assessment (LCA) as an environmental-impact assessment tool has received increasing attention over the years. Unlike the water footprint (WF) and carbon footprint (CF) assessments, whose focus is only on a single environmental aspect, the LCA systematically analyzes the different impacts along the entire life cycle, making possible the identification of potential environmental tradeoffs. In Korea, LCA has drawn much attention from both industry and academia since the mid-1990s. However, the level of Korean-related LCA studies with respect to different sectors in the last 20 years has not been analyzed. This study, therefore, sought to assess the status of environmental Life Cycle Assessment (LCA) studies in South Korea. Specifically, the study focused on a bibliometric review of LCAs conducted in South Korea in the last 20 years and identified potential research gaps. Online searches of English-written articles published between 2000 and 2019 were conducted on Google, Google Scholar, Scopus, and Web of Science databases, using eligible keywords. At the end of the search, about 91 LCA-related studies were discovered for South Korea within the study period. The majority of these studies focused on the construction (47%) and energy (30%) sectors, with fewer environmental studies on manufacturing (11%), transportation (9%), agriculture (2%), and information and communication (1%) industries. Based on publication trends, results show that LCA studies in South Korea have been on the rise in the past 20 years, even though the number of publications has not followed a constant pace. In comparison with the economic sectors of the country, reports show an inadequacy in the coverage of major industries of growing economic relevance, such as tourism, health, and agriculture, suggesting a need to increase and improve LCA-related studies in these sectors.

Evaluation of Road Transport Pollutant Emissions from Transporting Building Materials to the Construction Site by Replacing Old Vehicles

Since the life cycle of a building spans more than 50 years, studies of the environmental impacts in the construction industry have focused on reducing the energy consumption and greenhouse gas emissions during the operation and maintenance phase. The products of the construction industry are assembled using various building materials manufactured outside of the construction site. Consequently, it is essential that the manufactured building materials be transported to the construction site using various types of transportation methods. However, there is a lack of studies that assess the pollutant emissions of road transport while executing a construction project. The purpose of this study is to investigate the changes in the road pollutant emissions when the old diesel vehicles for transporting building materials are replaced according to enhanced pollutant emission regulations. In this study, we found that approximately 89, 64, 77, and 64% of NO_x, VOC, PM, and CO, respectively, were emitted during transportation of building materials as a proportion of the emissions during the construction of the structure. The analyzed results also show that about 10, 35, 23, and 35% of NO_x, VOC, PM, and CO, respectively, were generated from material transportation as a proportion of the emissions from finishing the work. It is expected that a reduction in pollutant emissions from transporting building materials of up to approximately 64, 39, 49, and 27% of NOx, VOC, PM, and CO, respectively, can be achieved when vehicles registered before 2003 are replaced with ones that adhere to the tightened regulations.

Framework for Designing Sustainable Structures through Steel Beam Reuse

The architecture, engineering, and construction sector requires carbon-intensive materials, such as steel, in the construction process and generates a large amount of waste in the life cycle. This causes global warming and waste problems. The demand for the reuse of construction materials is increasing, although it is not the convention, to reduce the environmental impact. Although the sustainable effect of the reuse of materials has been proven in several studies, materials are not always reused in practice, owing to the lack of an information system for reusable materials and the economic uncertainty. In this study, we propose a framework for designing structures using reusable steel beams. The design framework consists of a material bank and a design support tool. The material bank provides information on reusable materials based on the building information modeling. The design support tool generates efficient material procurement plans and provides information about the environmental and economic impact of the project. In a case study used to verify the framework, CO2 emissions were reduced by up to 77% through material reuse, which was consistent with the results of previous studies. However, owing to the cost of processing reusable materials, the overall cost was found to increase by up to about 40%. Therefore, an economic analysis over the entire life cycle when using reusable materials needs to be done.

Comparison of Environmental Impact of Three Different Slab Systems for Life Cycle Assessment of a Commercial Building in South Korea

The environmental impacts of the construction stage should be considered since a large amount of building materials are used to construct a building at this stage. Studies on the improvement of construction techniques or the application of newly developed construction methods for reducing the environmental impacts are relatively scant compared to other topics of studies. This study aimed to assess and compare the environmental impacts of the ordinary solid slab, the flat plate slab and the voided slab system during the construction phase. A process-based quantitative model was adopted to evaluate the environmental impacts and the comparative results were analysed to demonstrate the significant characteristics of the environmental impacts of the construction of slab in a building. The assessment results show that the environmental impacts from the ordinary solid slab are the highest and the voided slab system is the lowest among three slab systems. As the slab system of the studied building was replaced, it was shown that the environmental impact indicators showed the decreased tendency. Based on the results of environmental impact reduction from the ordinary solid slab, the flat plate slab and the voided slab system, the voided slab system would have the least environmental impact in all indicators.

Evaluation of Carbon Dioxide Emissions amongst Alternative Slab Systems during the Construction Phase in a Building Project

Global warming is now considered to be one of the greatest challenges worldwide. International environmental agreements have been developed in response to climate change since the 1970s. The construction industry is considered one of the main contributors to global warming. In order to mitigate global warming effects, the construction industry has been exploring various approaches to mitigate the impacts of carbon dioxide emissions over the entire life cycle of buildings. The application of different structural systems is considered a means of reducing the carbon dioxide emissions from building construction. The purpose of this research is to assess the environmental performance of three different slab systems during the construction phase. In this study, a process-based life cycle assessment (LCA) method was applied in order to evaluate the level of performance of the three slab systems. The results showed total CO2 emissions of 3,275,712, 3,157,260, and 2,943,695 kg CO2 eq. for the ordinary reinforced concrete slab, flat plate slab, and voided slab systems, respectively. The manufacturing of building materials is by far the main contributor to CO2 emissions, which indicate 3,230,945, 3,117,203, and 2,905,564 kg CO2 eq., respectively. Comparing the building materials in the three slab systems, reinforcing bars and forms were significant building materials to reduce the CO2 emissions in the flat plate slab and voided slab systems. In this study, reinforcing bars were the main contributor to lowering the carbon dioxide emissions in the flat plate slab and voided slab systems. The results of this study show that amongst all the three different slab systems, the voided slab system shows the greatest reduction potential. Moreover, replacing the ordinary reinforced concrete slab system by alternative methods would make it possible to reduce the carbon dioxide emissions in building projects.

Reducing Greenhouse Gas Emissions and Costs with the Alternative Structural System for Slab: A Comparative Analysis of South Korea Cases

The construction industry is one of the main contributors to the production of large volumes of greenhouse gases, since it consumes a large quantity of energy and construction materials. The purpose of this research is to assess the environmental impacts and economic efficiency of the voided slab system compared to the ordinary reinforced concrete slab. A life cycle assessment (LCA) and the total cost of construction were calculated to evaluate the performance of both slab systems. Additionally, the total costs of construction for both cases were determined based on the unit price of the building materials. The results of this study indicate that manufacturing building materials contributes most to the total GHG emissions where concrete is responsible for nearly 1/2 of all emissions. Additionally, forms are the second largest contributor of the total GHG emissions and account for nearly 40% and 15% of emissions for the ordinary reinforced concrete slab and the voided slab system, respectively. This study verified that the voided slab system indicated better environmental performance than the ordinary reinforced concrete slab. The total GHG emissions of the ordinary reinforced concrete slab were 256,599 and 13,989 kg·CO2·eq, for concrete and forms, respectively. Additionally, the total GHG emissions of the voided slab system were 224,945 and 12,211 kg·CO2·eq. The reduction of GHG emissions from Case 1 for aboveground floors and Case 2 for underground parking was 12.3% and 12.7% over the ordinary reinforced concrete slab, respectively. The economic efficiency of the ordinary reinforced concrete slab and the voided slab system were assessed by comparison of the total costs of construction. This showed a total cost reduction of 12.3% and 11.2% for the case of applying the voided slab system to the aboveground floors and underground parking, respectively. Thus, replacing the ordinary reinforced concrete slab by the voided slab system in the aboveground floors and the underground would make it possible to decrease not only the emissions of GHG, but also the cost of construction.

Comparison of Carbon Dioxide Emissions of the Ordinary Reinforced Concrete Slab and the Voided Slab System During the Construction Phase: A Case Study of a Residential Building in South Korea

The construction industry not only consumes a lot of energy but also emits large volumes of carbon dioxide. Most countries have established target reduction values of the carbon dioxide emissions to alleviate environmental burdens and promote sustainable development. The reduction in carbon dioxide emissions in the construction industry has been taking place in various ways as buildings produce large quantities of the carbon dioxide over their construction life cycle. The aim of this study is to assess and compare the carbon dioxide emissions of an ordinary reinforced concrete slab and the voided slab system applied to a case study involving a commercial-residential complex building in South Korea. Process-based life-cycle assessment (LCA) is adopted to compute the carbon dioxide emissions during the construction phase, which includes all processes from material production to the end of construction. The results indicate that the total CO2 emissions are 257,230 and 218,800 kg CO2 for the ordinary reinforced concrete slab and the voided slab system, respectively. The highest contributor to CO2 reduction is the embodied carbon dioxide emissions of the building materials, which accounts for 34,966 kg CO2. The second highest contributor is the transportation of the building materials, accounting for 3417 kg CO2.

Peanut Shell for Energy: Properties and Its Potential to Respect the Environment

The peanut (Arachys hypogaea) is a plant of the Fabaceae family (legumes), as are chickpeas, lentils, beans, and peas. It is originally from South America and is used mainly for culinary purposes, in confectionery products, or as a nut as well as for the production of biscuits, breads, sweets, cereals, and salads. Also, due to its high percentage of fat, peanuts are used for industrialized products such as oils, flours, inks, creams, lipsticks, etc. According to the Food and Agriculture Organization (FAO) statistical yearbook in 2016, the production of peanuts was 43,982,066 t, produced in 27,660,802 hectares. Peanuts are grown mainly in Asia, with a global production rate of 65.3%, followed by Africa with 26.2%, the Americas with 8.4%, and Oceania with 0.1%. The peanut industry is one of the main generators of agroindustrial waste (shells). This residual biomass (25–30% of the total weight) has a high energy content that is worth exploring. The main objectives of this study are, firstly, to evaluate the energy parameters of peanut shells as a possible solid biofuel applied as an energy source in residential and industrial heating installations. Secondly, different models are analysed to estimate the higher heating value (HHV) for biomass proposed by different scientists and to determine which most accurately fits the determination of this value for peanut shells. Thirdly, we evaluate the reduction in global CO2 emissions that would result from the use of peanut shells as biofuel. The obtained HHV of peanut shells (18.547 MJ/kg) is higher than other biomass sources evaluated, such as olive stones (17.884 MJ/kg) or almond shells (18.200 MJ/kg), and similar to other sources of biomass used at present for home and industrial heating applications. Different prediction models of the HHV value proposed by scientists for different types of biomass have been analysed and the one that best fits the calculation for the peanut shell has been determined. The CO2 reduction that would result from the use of peanut shells as an energy source has been evaluated in all production countries, obtaining values above 0.5 ‰ of their total emissions.