Reporting Scope

Economy

Financial Performance (SK ecoplant)¹⁾

1) Separate basis

Financial Performance (Subsidiaries)¹⁾

1) Separate basis for each subsidiary

Environmental

Climate Change Response

Scope 1 & 2 Emissions (SK ecoplant)

1) Scope 1 & 2 Emissions were calculated based on a location-based approach. 2) Scope 1 & 2 Emissions Intensity: Scope 1 & 2 Emissions ÷ Domestic Revenue (separate basis) 3) Scope 2 emissions figures may vary depending on the classification of organizational boundaries as defined in the greenhouse gas statement verification manual and
detailed verification guidelines 4) Greenhouse gas emission figures may be subject to minor adjustments due to fluctuations in emission factors provided by steam suppliers

Scope 1 & 2 Emissions (Subsidiaries)

1) Scope 1 & 2 Emissions: Calculated on a regional basis

Scope 3 Emissions (SK ecoplant)

1) Total Scope 3 Emissions: Calculated based on domestic emissions; among the detailed items, only Category 15 (Investment) includes the overseas assets of investee
companies.

Energy Consumption (SK ecoplant)

1) Total Energy Consumption: Total Non-Renewable Energy Consumption + Self-Generated Solar Power 2) Energy Intensity: Total Energy Consumption ÷ Domestic Revenue (separate basis) 3) Renewable Energy Conversion Rate: (Total Renewable Energy Supplied ÷ Total Energy Consumption) × 100

Energy Consumption (Subsidiaries)

1) Total Energy Consumption: Total Non-Renewable Energy Consumption + Self-Generated Solar Power 2) Energy Intensity: Total Energy Consumption ÷ Revenue (separate basis) 3) Renewable Energy Conversion Rate: (Total Renewable Energy Supplied ÷ Total Energy Consumption) × 100 4) ESSENCORE’s Total Energy Consumption: 0.85 TJ (Due to the nature of the business, only electricity consumption at branch offices and subsidiaries is included in the tally)

Environmental Management

Waste Generation and Treatment by Type (SK ecoplant)

1) Total Waste Generation Intensity: Total Waste Generated ÷ Revenue (separate basis) 2) Waste Recycling Rate: (Total Waste Recycled ÷ Total Waste Generated) × 100

Waste Generation and Treatment by Type (Subsidiaries)

1) Total Waste Generation Intensity: Total Waste Generated ÷ Revenue (separate basis) 2) Waste Recycling Rate: (Total Waste Recycled ÷ Total Waste Generated) × 100 3) Construction Waste Generated: Due to the nature of their business areas, SKOP, SK tes, and SKAP do not track construction waste generation or disposal volumes

Water Intake and Usage (SK ecoplant)

Water Intake and Usage (Subsidiaries)

1) SKAP Total Water Consumption: Total Water Intake (1,170,187 tons) minus Total Water Discharge (327,598 tons) 2) SKOP Total Water Consumption: Total Water Intake (154,188 tons) minus Total Water Discharge (43,046 tons)

Environmental Education Performance (SK ecoplant)

1) Participation Rate: (No. of Participants ÷ Total No. of Eligible Employees (as of the time of training)) × 100 2) Training Hours and Cost per Employee: Total Training Hours or Training Cost ÷ No. of Participants; figures for 2023–2024 have been revised due to changes in internal
calculation standards

Environmental Education Performance (Subsidiaries)

1) Participation Rate: (No. of Participants ÷ Total No. of Eligible Employees (as of the time of training)) × 100 2) Training Hours and Cost per Employee: Total Training Hours or Training Cost ÷ No. of Participants

Status of Major Environmental Regulation Violations (SK ecoplant)¹⁾

1) Based on cases each involving fines or penalties of KRW 10 million or USD 10,000 or more.

Status of Major Environmental Regulation Violations (Subsidiaries)¹⁾

1) Based on cases each involving fines or penalties of KRW 10 million or USD 10,000 or more.

Sustainable Products and Services

Green Building Certification (SK ecoplant)

1) Green Building Certification (G-SEED): A system that grants eco-friendly building certification to structures that contribute to energy conservation and the reduction of
environmental pollution throughout the entire process, including design, construction, and maintenance. 2) Building Energy Efficiency Rating : A certification system designed to expand demand for high-energy-performance buildings and promote awareness of effective building
energy management by providing quantitative and objective information on building energy performance.

Eco-friendly Building Revenue (SK ecoplant)

1) Eco-friendly Revenue: Eco-friendly revenue is defined as revenue from products that have received third-party certification, and includes revenue generated from projects
that have completed final and preliminary certification 2) Eco-friendly Revenue Ratio = (Eco-friendly Revenue ÷ Revenue (separate basis)) × 100

R&D Investment Status (SK ecoplant)

1) R&D Investment Ratio to Revenue: (R&D Expenditures ÷ Revenue (separate basis)) × 100

R&D Investment Status (Subsidiaries)

1) R&D Investment Ratio to Revenue: (R&D Expenditures ÷ Revenue (separate basis)) × 100

Patent Status (SK ecoplant)

Patent Status (Subsidiaries)

Social

Occupational Safety and Health at Worksites

Occupational Safety and Health Training Performance (SK ecoplant)

Status of Occupational Safety and Health Grievance Handling by Biz. Partner (SK ecoplant)

1) Improvement Action Rate: (No. of Improvement Actions Taken ÷ No. of Improvement Suggestions) × 100

Status of Occupational Safety and Health Law Violations (SK ecoplant)

Status of Occupational Safety and Health Law Violations (Subsidiaries)

Occupational Safety and Health Management Indicators (SK ecoplant)

1) Lost-Time Injury Rate (LTIR): (Lost Time Incidents ÷ Total Work Hours) × 200,000

Occupational Safety and Health Management Indicators (Subsidiaries)

1) Total Recordable Incident Rate (TRIR): (Total Recordable Incidents ÷ Total Work Hours) × 200,000 2) Lost-Time Injury Rate (LTIR): (Lost Time Incidents ÷ Total Work Hours) × 200,000 3) ESSENCORE selects and manages certain occupational safety and health management indicators for its employees

Sustainable Supply Chain

Raw and Recycled Material Usage (SK ecoplant)

Eco-Friendly Product Procurement Status (SK ecoplant)

1) Eco-friendly Product Procurement Amount: Officially Certified Eco-friendly Products + Other Eco-friendly Product Procurement Amount 2) Other Eco-friendly Product Procurement Amount: Purchases of products that meet the eco-friendly product certification systems and standards established by SK ecoplant 3) Eco-friendly Procurement Ratio: (Eco-friendly Product Procurement Amount ÷ Total Procurement Amount) × 100

Performance of Shared Growth Support Programs (SK ecoplant)

1) HR and Recruitment Support Program: Integrated operation of legacy “Job Creation via Industry-University Partnership” and “Enabling Participation in Job Fairs” programs as
the HR and Recruitment Support Program

Biz. Partner Grievance Reception and Resolution Status (SK ecoplant)

1) Grievance Resolution Rate: (No. of Grievances Resolved ÷ No. of Grievances Received) × 100

Subcontract Dispute Mediation Committee Case Status (SK ecoplant)

Biz. Partner ESG Improvement Action Implementation Status (SK ecoplant)

1) No. of Biz. Partner Participating in ESG Evaluation: 80% of No. of Core Biz. Partner (as of 2025) 2) No. of Biz. Partner Under Priority Management (Implementation of improvement actions): The number of Biz. Partners identified through ESG evaluation results as having
high ESG risks or requiring urgent improvement and thus requiring priority management 3) Implementation Rate of Improvement Actions: (No. of Biz. Partners that implemented improvement actions ÷ No. of Biz. Partner Under Priority Management) × 100

Quality Management and Customer Satisfaction

Quality Training Performance (SK ecoplant)

1) Participation Rate: (No. of Participants ÷ Total No. of Eligible Employees (as of the training date)) × 100

Status of Violations of Product and Service Safety Regulations (SK ecoplant)

Status of Violations of Product and Service Safety Regulations (Subsidiaries)

Customer Satisfaction Survey Results (SK ecoplant)¹⁾

1) Scores are based on a 5-point scale.

Customer Happiness Center – VoC Handling Status (SK ecoplant)

1) Processing Rate: (No. of Cases Processed ÷ No. of Reports Received) × 100

Human Resource Management

Employee Status (SK ecoplant)

1) Total No. of Employees: The sum of executives, regular employees, part-time employees, and contract employees; 76 temporary employees are excluded from the total (as of
December 31 of the reporting year). 2) Calculated excluding the 140 employees in the Gas & Materials business division, which was newly incorporated in December 2025

Employee Status (Subsidiaries)

1) Total No. of Employees: The sum of executives, regular employees, part-time employees, and contract employees; temporary employees are excluded from the total (as of
December 31 of the reporting year).

New Employee Recruitment Status (SK ecoplant)

1) Total No. of New Hires: Employees transferred from SKEE to SK ecoplant not included

New Employee Recruitment Status (Subsidiaries)

1) Since some of SK tes’s new hires did not disclose their gender, there is a discrepancy between the combined number of males and females and the Total No. of New Hires

Employee Diversity Status (SK ecoplant)

1) Percentage of Employees with Disabilities: Calculated based on Article 28 of the Act on the Employment Promotion and Vocational Rehabilitation of Persons with Disabilities
and Article 25 of the Enforcement Decree of the same Act

Employee Training and Education Performance (SK ecoplant)

1) Total Training Hours: Total hours spent by executives, regular employees, part-time employees, and contract employees on SK ecoplant’s mySUNI platform + hours spent on
internal and external training + hours spent on mandatory training such as sexual harassment prevention 2) Training Hours and Expenses per Employee: Total Training Hours or Total Training Expenses ÷ Total No. of Employees (as of December 31 of the reporting year)

Employee Training and Education Performance (Subsidiaries)

1) Total Training Hours: Total hours spent by executives, regular employees, part-time employees, and contract employees on internal and external training + hours spent on mandatory training such as sexual harassment prevention 2) Training Hours and Expenses per Employee: Total Training Hours or Total Training Expenses ÷ Total No. of Employees (as of December 31 of the reporting year)

Employee Performance Evaluation Status (SK ecoplant)

1) No. of Eligible Employees : Number of regular employees, excluding those who have been with the company for less than 6 months (e.g., those on leave or who joined mid-year) and contract employees 2) Evaluation Rate: (No. of employees evaluated ÷ No. of Eligible Employees) × 100

Parental Leave Utilization Status (SK ecoplant)

Employee Welfare Support Status (SK ecoplant)

1) Employee Welfare Expenses: Calculated based on specific items related to employee welfare (welfare expenses in the business report include various incentives and other
related items; the calculation criteria differ from those used in this report) 2) Employee Health Check-up Participation Rate: (No. of employees who underwent health check-ups ÷ Total No. of Employees (as of December 31 of the reporting year)) × 100 3) Participation Rate in Flexible Work Arrangements: (No. of employees who used flexible work arrangements ÷ Total No. of Employees (as of December 31 of the reporting
year)) × 100

Turnover and Resignation Status (SK ecoplant)

1) Total Resignation Rate: (Total No. of Resignations ÷ Total No. of Employees (as of December 31 of the reporting year)) × 100 2) Total Resignation Rate for 2023–2024: Figures revised due to a change in the calculation criteria for the Total No. of Employeess, now based on December 31 of the reporting
year 3) Voluntary Turnover Rate: (No. of Voluntary Leavers ÷ Total No. of Employees (as of December 31 of the reporting year)) × 100 4) Voluntary Turnover Rate for 2023–2024: Figures revised due to a change in the calculation criteria for the Total No. of Employeess, now based on December 31 of the
reporting year

Employee Engagement Survey Results (SK ecoplant)

Management Development Council Meeting Status (SK ecoplant)

1) Grievance Resolution Rate: (No. of Grievances Resolved ÷ No. of Grievances Received) × 100

Human Rights Management

Status of Human Rights Grievance Receipt and Resolution (SK ecoplant)

1) Grievance Resolution Rate: (No. of Grievances Resolved ÷ No. of Grievances Received) × 100

Status of Human Rights Grievance Receipt and Resolution (Subsidiaries)

1) Grievance Resolution Rate: (No. of Grievances Resolved ÷ No. of Grievances Received) × 100 2) If the investigation finds no evidence of a human rights violation or determines that the incident does not constitute a human rights violation, the case is closed without
disciplinary action or warning.

Human Rights Training Performance (SK ecoplant)

1) Participation Rate: (No. of Participants ÷ Total No. of Eligible Employees (as of the training date)) × 100 2) Training Hours per Employee: Total Training Hours ÷ No. of Participants

Human Rights Training Performance (Subsidiaries)

1) Participation Rate: (No. of Participants ÷ Total No. of Eligible Employees (as of the training date)) × 100 2) Training Hours per Employee: Total Training Hours ÷ No. of Participants

Social Contribution

Employee Volunteer Activity Performance (SK ecoplant)

1) Volunteer Participation Rate: (Total No. of Participants ÷ Total No. of Employees (as of December 31 of the reporting year) × 100 2) 2023 Volunteer Participation Rate: Figures revised due to a change in the calculation criteria for the Total No. of Employeess, now based on December 31 of the reporting year 3) Total Volunteer Hours: For certain activities such as the One Meal Sharing Project and the Goods for Good Donation Campaign, the number of participations was converted
into volunteer hours. 4) Volunteering Hours per Person: Total Volunteer Hours ÷ Total No. of Participants

Employee Volunteer Activity Performance (Subsidiaries)

1) Volunteer Participation Rate: (Total No. of Participants ÷ Total No. of Employees (as of December 31 of the reporting year) × 100 2) Volunteering Hours per Person: Total Volunteer Hours ÷ Total No. of Participants

Social Contribution Investment Status (SK ecoplant)

1) Social Contribution Activity Expenses: Includes cash, time, goods, and management fees, social contribution activity expenses, and costs associated with “Happy Space”
environmental improvement activities

Key Social Contribution Program Performance (SK ecoplant)

Information Security

Information Security Investment Status (SK ecoplant)

1) Information Security Investment Ratio: (Information Security Investment ÷ IT Budget) × 100

Status of Cybersecurity Simulation Training (SK ecoplant)

Information Security Regulation Violation Status (SK ecoplant)

Information Security Regulation Violation Status (Subsidiaries)

Governance

Governance Structure

Board of Directors Composition (SK ecoplant)¹⁾

1) Board Composition: As of March 31 of the year following the reporting year 2) Industry Experts: Industry experts based on the BSM (Board Skills Matrix) 3) Finance experts: Finance experts as defined by the Commercial Act (including non-executive directors) 4) Experts in Other Fields: Registered directors other than industry and finance experts

Board of Directors Operations (SK ecoplant)¹⁾

1) Board of Directors Operations: As of December 31 of the reporting year

Board Committee Status (SK ecoplant)¹⁾