Environmental Impact Assessments (EIA)

In the current era of the “Green Economy” (BCG Model). The Environmental Impact Assessment (EIA) has evolved from a simple checklist into a mandatory strategic requirement. This for almost every significant development project in Thailand. As of 2026, the intersection of the Clean Air Act, Climate Change Act, and updated NEQA . This being the Enhancement and Conservation of National Environmental Quality Act. This has made the EIA process more transparent than before.

An Environmental Impact Assessments (EIA) is more like a predictive tool. It identifies the potential environmental as well as the health and social consequences of a project before it begins. In Thailand, this is not just a recommendation. It is a statutory requirement under Section 48 of the NEQA. 

Section 48 For the benefit of enhancing and conserving environmental quality.

By 2026, the scope of an EIA has expanded to include Carbon Footprint Accounting and Climate Resilience Strategy. Developers are now required to prove not only that they won’t pollute the local water.

The primary regulatory body is the Office of Natural Resources and Environmental Policy and Planning (ONEP). However in 2025, a reorganization saw the birth of the Department of Climate Change and Environment (DCCE). This department which now works alongside ONEP to ensure that EIA reports align with Thailand’s 2050 Carbon Neutrality goal.

Types of Assessments in 2026

• IEE (Initial Environmental Examination): This is normally required for smaller projects. Those projects with minor impacts. These types of projects are often managed at the provincial level.
• EIA (Environmental Impact Assessment): This is the standard for medium-to-large projects in Thailand. These tend to include projects such as condominiums (80+ rooms) or mid-sized factories.
• EHIA (Environmental Health Impact Assessment): These tend to be reserved for “mega-projects” or hazardous industries (e.g., power plants, deep-sea ports) that could seriously impact the health of local communities.

The most significant operational change in 2026 is the National Digital EIA Portal. Those day of submitting thousands of pages is long gone.

Real-Time Monitoring: Large-scale projects are now required to install IoT sensors for air and water quality that feed data directly to the ONEP and DCCE dashboard.

Public Transparency: Every submitted EIA report is now accessible to the public online. This allowing local communities as well as NGOs to review and comment on the findings.

Phase 1: Screening Selection

Firstly check if your project is on the regulated list. You will note that list has been expanded in 2026. This now also includes large-scale data centers and renewable energy farms like floating solar. This which were previously in a grey area. Proponents must hire a ONEP-registered consultancy firm. Using an unlicensed consultant is a criminal offense under the 2025 amendments.

Phase 2: Scoping and Baseline Data Collection

The consultant must conduct a “Scoping” exercise to define the boundaries of the study. This includes:

Physical: Soil, air, water, and noise.

Biological: Impact on local flora and fauna this with new 2026 standards on migratory bird patterns.

Human Use: Infrastructure, land use, and transportation.

Quality of Life: Socio-economics and health.

Phase 3: Public Participation (The “Heart” of the EIA)

This is where many projects fail. Under the 2026 guidelines, you must conduct at least two rounds of public hearings.

The “Social License”: In 2026, ONEP rarely approves a project that faces overwhelming local opposition. The hearings must be inclusive, including materials in local dialects if necessary. Likewise specifically inviting groups representing the newly recognized diverse family structures.

Phase 4: Mitigation Measures

If a project will cause noise pollution. Then the EIA must specify the exact height and material of sound barriers. If it will produce wastewater, the exact specifications of the treatment plant must be included. These measures are not “suggestions”—they become legal conditions of the project’s permit.

Real Estate & Hospitality

For developers in Phuket, Bangkok, or Samui, the thresholds are strict:

Condos/Hotels: 80 rooms or more, or a total area of 4,000 sqm.

Environmentally Protected Areas (EPA): In places like Samui or parts of Chonburi, the thresholds are even lower, sometimes requiring an IEE for as few as 10 rooms.

Industrial and Manufacturing

The 2026 Clean Air Act has added “Air Pollutant Fees” to the EIA process. Factories must calculate their PM2.5 and CO2 emissions. High-emitters must pay into the Clean Air Fund. This fund is then used local reforestation or community health projects.

In 2026, the “polluter pays” principle is enforced. See Toxic Torts

License Revocation: If a developer fails to submit their bi-annual Monitoring Report. The local municipality has the power to suspend their building permit immediately.

Criminal Penalties: Falsify EIA data by the director of the company will face up to 3 years in prison and fines of up to 10 million THB.

Civil Liability: Community members can use the EIA report. This as evidence in the Central Administrative Court. They will do this when they seek compensation for damages to their health or property.

A unique aspect of 2026 legal practice is how Family Law intersects with EIA Social Impacts. When an infrastructure project (like a new railway) requires land expropriation. Then you have to look at the social impact assessment for same-sex spouses . This as legal beneficiaries of compensation and relocation assistance. This ensures the “Socio-Economic” section was inclusive under the new Civil and Commercial Code.

Based on 2025 data that we have looked at. The top reasons for EIA rejection in Thailand include the following:

Insufficient Engagement: You may have failed to reach a diverse enough cross-section of the local community.

Outdated Data: Using air quality stats that were more than 12 months old.

 Weak Mitigation: Proposing “greenwashing” solutions that don’t actually meet the 2026 technical standards for carbon reduction.

Incompatibility with Local Plans: The project contradicts provincial “Green Growth” zoning.

Looking ahead, Thailand is moving toward Strategic Environmental Assessments (SEA). While an EIA looks at a single project, an SEA looks at an entire region (e.g., the Eastern Economic Corridor). By 2026, developers are being encouraged to align their individual EIAs with these broader SEAs to speed up the approval process.

Summary Checklist for Developers in 2026:

• Verify project size against the 2026 ONEP/DCCE regulated list.
• Appoint a ONEP-registered consultant.
• Budget for two rounds of public hearings.
• Likewise ensure the design includes Net-Zero compatible technologies in it.
• Install IoT monitoring hardware before the operational phase.
• Likewise you will also need to update HR and Social plans to include inclusive family recognition for compensation.

Conclusion

The Environmental Impact Assessment in Thailand is no longer a static document. The EIA is a living commitment to the Kingdom’s sustainable future. For investors, a successful EIA is the ultimate “Social License to Operate,”. Likewise ensuring that business growth does not come at the expense of Thailand’s natural beauty or its people’s health.In addition by embracing the digital and social shifts of 2025–2026, developers can navigate these waters smoothly and contribute to the nation’s ambitious environmental goals.

Since you are looking for specific technical requirements.  I have detailed the mandatory checklists for Hotel Development and Factory Operations. This is based on the updated 2026 standards. These lists incorporate the recent integration of the Clean Air Act and the Marriage Equality Act into the social and environmental scoring of projects.

1. 2026 Technical Requirements: Hotel & Resort EIA

In 2026, any hotel project with 80 rooms or more, or a total floor area exceeding 4,000 square meters. They must now  obtain EIA approval before a building permit is issued.

Core Technical Checklist

Wastewater Management: Must include a dedicated treatment plant. One that is more than capable of handling 120% of peak capacity. Effluent must meet the PCD (Pollution Control Department) 2026 Standards for BOD, TKN, and grease/oil levels.

Public Participation (2 Rounds): 

Round 1: The first is conducted within a 5km radius of the announced project.

Round 2: Focused on presenting specific mitigation measures. These include noise barriers as well as traffic rerouting.

Green Space & OSR: Minimum Open Space Ratio (OSR) of 30%. This with at least 50% of that being “Permeable Green Surface” to prevent urban heat island effects.

Traffic Impact Study: Mandatory for hotels on “Orange” or “Brown” zones. These are the medium or high density areas. Likeiwse in it is to prove no more than a 10% decrease in local traffic flow speed during peak hours.

[NEW 2026] PM2.5 & Air Quality: Mandatory installation of real-time air quality sensors. This at the construction site boundary, linked to the BMA/ONEP Digital Dashboard.

2. 2026 Technical Requirements: Industrial & Factory EIA

Industrial projects are governed by the Factory Act. This in addition to the newly tightened law called the Clean Air Management Act (2025/2026) in Thailand.

Mandatory “Polluter Pays” Checklist

Emission Control (Clean Air Act Integration): You will note that factories must provide a Continuous Emission Monitoring System (CEMS) for their stacks. Under the new 2026 rules, specific “Air Pollutant Fees” are levied. This based on your quarterly emission reports.

Hazardous Waste Tracking: Full integration with the Manifest System 2.0. This requiring blockchain-verified tracking of industrial waste from the factory to the disposal site.

Noise as well as Vibration: There needs to be continuous monitoring during the piling and operational phases of the project. This with a maximum daytime limit of 70 dB(A) at the site boundary.

Chemical Safety: Submission of a Material Safety Data Sheet (MSDS) for all stored chemicals. In addition you must have an emergency evacuation plan for nearby communities within a 2km radius.

[NEW 2026] Climate Resilience: A “Carbon Footprint for Organizations” (CFO) report is now a prerequisite. Likewise, anticipating the full rollout of the Climate Change Act.

3 The “Social & Family” Impact Component (2026 Updates)

Under the 2026 EIA guidelines. The new “Socio-Economic Impact” chapter of your report must now reflect the following legal realities:

Summary of Regulatory Milestones (Early 2026)

Alcohol Deregulation: If your hotel or commercial project involves F&B. I addition note that the January 2026 Ordinance should abolished alcohol zoning, potentially allowing 24-hour zones in specific “Red Zone” districts.

Digital Submission: All EIA reports must now be submitted via the ONEP Smart EIA portal. Physical paper submissions are no longer accepted for new projects as of January 1, 2026.

The information contained in our website is for general information purposes only and does not constitute legal advices. For further information, please contact us.