Environmental Performance Evaluation Using Green Construction Site Index (GCSI) for Residential and Non-Residential Building Construction

The realization of sustainable development is the responsibility of every construction element to carry out the prevention of development activities that have the potential to damage and cause environmental problems. Alignment of the ongoing construction project with the maintenance of environmental balance can be carried out through environmental management and monitoring in construction site. One of them, through an assessment and evaluation related to the implementation of sustainable construction, is one of the efforts that can be made to prevent environmental damage due to construction activities. The guideline or measuring tool is the Green Construction Site Index (GCSI) to evaluate six building construction which are grouped into two categories (residential and non-residential buildings). A quantitative measuring instrument to measure five elements consisting of waste minimization, sustainable green construction, resource management, understanding of construction waste and environmental performance on construction as parameters in the implementation of construction activities. The average values obtained from the two categories of buildings based on five elements respectively are 4.11, 3.94, 4.27, 3.85, and 4.20.


Introduction
The value of construction completed has increased every year which indicates that construction activity in Indonesia is always growing.This has a positive impact on the economic and social aspects, but not necessarily on the environmental aspect sector growth triggered by several things, including: (a) overpopulation; (b) overconsumption [1].The energy consumption and air emissions associated with the construction industry have adverse effects on the environment.This has led to an increased focus on sustainability within the industry, resulting in the emergence of various global environmental concepts and efforts to create and implement eco-friendly approaches like environmentally conscious construction, sustainable building, and eco-friendly financing [2].The negative environmental impact of the construction sector is regarded as one of the world's challenges.The construction industries generate severe implications to the environment.The construction industry consumes large amounts of raw materials, such as stone, wood, water, and so on.In addition, the required built-in infrastructure provides years of service without any security issues.Thus, the design, construction, maintenance, and demolition are important to reduce the economic, environmental, and social consequences [3].High quality infrastructure projects, primarily for commercial and residential use, are the main source of waste generation.The selection of building materials, processing, transportation, construction, and maintenance that finally turn into waste, had to be considered to minimize construction waste [4].In comparison to other 1321 (2024) 012045 IOP Publishing doi:10.1088/1755-1315/1321/1/012045 2 sectors, construction waste management encounter more risks due to uncertainties occurring because of various construction practices and working conditions.[5] Sustainable construction is the most important issue in recent years besides construction technology and building structures and systems [6].The purpose of sustainable construction is to create buildings based on designs that are environmentally friendly, efficient in the use of natural resources, and environmentally friendly during building operations [1].That is why sustainable construction has recently become very important [3].This is in line with the research objective to analyze the Green Construction Site Index (GCSI) in evaluating two categories of construction project which is included in the categories of non-residential and residential buildings.

Materials and methods
The analysis cantered on primary data acquired from six buildings: three were classified as category I (residential construction) and three as category II (residential construction).These buildings are strategically located in the central city of Semarang, surrounded by residents.Given their location in a densely populated area, it's paramount to assess the implementation of green construction in these projects.Large-scale construction in such areas can significantly affect the local community and environment.A questionnaire survey was administered throughout the construction phase to gather primary data.In the study, the respondents comprised members from planning consultants and primary contractors, totalling 60 respondents, who were given a questionnaire to gauge the efficacy and adherence to green construction principles.The Green Construction Site Index (GCSI) served as the quantitative tool for this assessment.The GCSI incorporates five key elements: sustainable green construction, resource management, construction site performance, and construction waste management.Furthermore, the evaluation was based on 133 distinct criteria categorized into five major factors, as previously mentioned.These 133 criteria served as the foundation for the assessment.Respondents validated these factors, ensuring their relevance and comprehensiveness.A score between 0 and 1.24 indicates a "lack of commitment", meeting only 20% of the essential factors.Scores between 1.25 and 2.44 highlight a "need for improvement", meeting 40% of the factors.A "good" classification is achieved with scores ranging from 2.45 to 3.74, representing a 60% adherence to the factors.Lastly, scores between 3.75 and 5.0 denote an "excellent" rating, implying compliance with at least 80% of the 133 factors.

Waste minimization
The element of waste minimization can be interpreted as an effort made by a construction project to minimize waste resulting from the construction process as much as possible.The construction project reflected the direct correlation between construction output and extended environmental impacts [7].In the waste minimization element, there are five main factors that become the focus of the assessment of this element, namely the application of environmentally friendly products, the use of factory-made construction units, the ability of factory-made subcontractors, completeness of design and construction planning, and completeness of contract documents.Then given a score to determine the extent of consciousness of the ongoing project as proven in Table 1.
Table 1 .89Category score: 1.0 -1.9 = lack of commitment; 2.0 -2.9 = need improvement; 3.0 -3.9 = good; 4.0 -5.0 = excellence; Table 1 shows that the index of waste management carried out by six projects assessed is included in excellence with an average score 4.11, compiled from five indicators.The project that deserved excellence category was Category I (residential building), there were project #1 (index=4.66),project #2 (index=4.23),and project #3 (index=4.06).Even though they were in the excellence category, the project that was included in Category I had some problems that showed by the lowest index.Project #1 get the lowest score in the application of environmentally friendly products indicator (3.32) is mean that the construction project needs to improve the use of green products.Meanwhile project #2 and project #3 were needed to increase the order of pre-cast items because the indicator use of factory-made construction units was placed in the lowest score (3.00).Category II (non-residential building) was lower than Category I (residential building) the projects that were included were in a good category.The lower score in Category I that included in need improvement category (index=2.49)was application of environmentally friendly products category.This index must be maintained and improve for all project, because five from six project get the lowest score there.

Sustainable green construction
To stabilize sustainability necessities and the call for affordable construction, one capability approach is to aid efficiency and use the sustainability overall performance [8].The research before find that prefabricated construction reduces construction waste by using 12.22% and 60-70% reduction of waste with sustainable techniques as compared with conventional construction [9,10].Sustainable green construction can be defined as the achievement of projects carried out based on several acceptable criteria in counteracting the negative impacts that occur during the construction project.The second element in the Green Construction Site Index (GCSI) is sustainable green construction.This element consists of five indicators.As shown in Table 2, the five indicators include the provision of trash bins at construction project sites, implementation of construction waste regulations, documentation reports on the reuse and recycling of construction waste, maximum reuse of building components, and utilization of recycled materials.73 Category score: 1.0 -1.9 = lack of commitment; 2.0 -2.9 = need improvement; 3.0 -3.9 = good; 4.0 -5.0 = excellence; Table 2 explains how the project applies the indicators of sustainable green construction in six construction projects.The data shows that the highest to the lowest scores based on the five indicators is project #2 (4.66), followed by project #3 (4.63), project #4 (4.42), project #5 (3.79), project #1 (3.392), and project #6 (2.73).The indicator that had to get more attention is the utilization of recycled materials it because the average score only till 3.17 which mean lower than other indicators.Moreover, three of six projects get need improvement category (2.00).Project #6 had the lowest score (2.73) it was included in the need improvement category, from data the implementation of the construction waste arrangement indicator in this project only had lack of commitment category (1.00).It is necessary to improve arrangement which include rules on dealing with wastes-by-wastes generators, installing a data board to word classes for isolating wastes, preventing mixing wastes with soil, shortening the duration of collection waste in a site, and shortening the duration of taking waste out of a site.

Resource management
In the implementation of material management, knowledge of the source of material which often becomes the rest of the material includes demolition waste, which is the result of demolition or destruction of old buildings and construction waste, which comes from construction [11].Elements of resource management which has five fundamental factors that are characteristic to evaluating present practices in the field practices of a construction site.This element determines assessing construction activities through the preparation of material procurement procedures in the achieved construction environment, the selection and use of materials, assessment of material waste, steel reinforcement waste control indicators, and concrete waste control indicators as shown in table 3. .51Category score: 1.0 -1.9 = lack of commitment; 2.0 -2.9 = need improvement; 3.0 -3.9 = good; 4.0 -5.0 = excellence.Table 3 demonstrates that, utilizing five specific metrics, the mean waste score across four construction initiatives is 4.27, classified as 'excellence'.These projects have satisfactorily met the established standards.To uphold this index, it's crucial to enhance aspects currently rated as 'good' and to focus on areas needing improvement.In terms of material procurement planning in construction settings, the average score is 4.50, denoting 'excellence'.Similarly, the average score for material selection and usage is 4.50, also indicating 'excellence'.The evaluation of material waste stands at an average of 3.67, which is 'good', with the steel reinforcement waste management scoring 4.17 ('excellence'), and the control of concrete waste achieving an average of 4.50.According to these assessment indices, all projects are considered 'excellent' in the area of material procurement preparation in the construction context.Notably, project #6's material waste assessment scored the lowest with 0.00.Of all the evaluated projects, project #4 stands out with the highest index score of 4.79.

Understanding of Construction Waste
The complexity with which the project was implemented to achieve the goals of the sustainable green building concept was recognized because it concerns all aspects of the project structure, including policies, processes, and practices.The elements of construction waste management can be interpreted as competencies that must be carried out by each engineer in carrying out the work that has been determined.The assessment indicators included in this element are training intending to reduce construction waste, socializing the movement for environmentally responsible attitudes, applying rewards and sanctions by environmental provisions or regulations, operating procedures for construction equipment, and awareness of the involvement of construction equipment in the environment as shown in Table 4. .06Category score: 1.0 -1.9 = lack of commitment; 2.0 -2.9 = need improvement; 3.0 -3.9 = good; 4.0 -5.0 = excellence.
In the factor understanding of construction waste the six project average index score is 3.85, which consists of training to reduce construction waste, socializing the movement for environmentally responsible attitudes, and applying rewards and sanctions in accordance with the provisions or environmental regulations, operating procedures of construction equipment, and awareness of the involvement of construction equipment in the environment.The assessment index achieved by the six projects reached the category of excellence, except for project #3 with a score of 2.83 which was still in the good category.

Environmental Performance on Construction
Project management is one of the which is the priority scale to sharpen implementation of construction projects effectively and efficient [12].Elements of environmental management assessment at construction site performance to assess a construction project does not cause adverse environmental impacts to have five main factors that function to assess environmental management at construction project sites as known with data (Table 5).76 Category score: 1.0 -1.9 = lack of commitment; 2.0 -2.9 = need improvement; 3.0 -3.9 = good; 4.0 -5.0 = excellence; Known in Table 5 the indicator understanding of construction waste in average of each indicator are 3.32 (good category), 4.67 (excellence category), 4.00 (excellence category), 4.33 (excellence category), and 4,67 (excellence category).Close on all projects be included to the excellence category.Meanwhile, In the meantime, a consideration highlighted that project #6 involved truly need improvement category (index=2.76).The fact could be explained so there are still issues with waste management and planning in the environmental sector, including the need for improvement in projects #2 and project #3.In project #1, it is shown that in some indicators it only belongs to the category of lack of commitment.Generally, estimated waste disposal (10-30%) is due to construction and demolition activities.It is estimated that approximately 10-30% of the waste sent to landfills around the world comes from construction and demolition activities.

Conclusion
Quantifying the assessment of ongoing projects through an on-site assessment of completion using the indexed GCSI clarified management's intent to meet the requirements of the concept of sustainable green building [13].The capacity of The Green Construction Site Index to assess an ongoing project demonstrates its usefulness related to the construction project by perspective on technicality-related parameters that quantitatively measure waste minimization, sustainable green construction, resource management, understanding of construction waste, and environmental performance on construction.The data collected from the six projects concluded that these are five parameters thoroughly and precisely calculated the strengths and weaknesses of each factor, indicator, and variable in the ongoing project.Another perspective is the ability of these tools to cross-check the five parameters and the category of construction that covers the dwelling and dwelling.The results show that the category of construction building is closely associated with the achievement of each positive and negative parameter.The most crucially, the Green Construction Site Index can quantitatively indicate the degree of correlation.

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Score of Waste Management

Table 2 .
Score of Sustainable Green Construction

Table 3 .
Score of Resource Management

Table 4 .
Score of Understanding of Construction Waste

Table 5 .
Score of Environmental Performance on Construction