As part of the Scenario Building process for TYNDP 2026, conducted jointly with ERAA 2025, a dedicated survey was conducted among national electricity and gas TSOs to validate input datasets. This was done to ensure alignment with European regulatory requirements and enhance transparency in scenario development. The survey builds on the data collection exercise for ERAA 2025 and TYNDP 2026 launched in November 2024 by ENTSO-E and ENTSOG, and guided by the “Joint ERAA 2025 and TYNDP 2026 Scenarios Data Collection Guidelines”1.
The survey was open between 25 July and 29 August 2025, and responses were requested as joint submissions from electricity and gas TSOs at national level. A total of 35 responses were received out of 40 countries, representing a high participation rate and providing a robust basis for assessing the quality, consistency, and transparency of the datasets used in Scenario Building 2026. All EU27 member states TSOs responded to the survey.
The responses collected through this survey confirmed the following points:
- National datasets submitted by TSOs are mostly aligned with key European requirements, including the TEN-E Regulation and the ACER Framework Guidelines. If not aligned, a justification was provided by the country.
- National datasets provided were mostly validated on national level before submission by Ministries, DSOs, other national authorities, or other stakeholders.
- National datasets are mostly compliant with the country NECPs or national strategies, and if not a justification was provided by the country.
Responses are published in Annex I as part of the TYNDP 2026 Scenarios Package, supporting a transparent scenario development process.
