9 Gap filling methodology //

Demand scenarios are developed based on the latest NECPs submitted by Member States. This bottom-up data collection forms the foundation of the NT.

As the aggregated EU27 Final Energy Consumption (FEC) in the 2030 NT dataset exceeds the EU target of 763 Mtoe set under the Energy Efficiency Directive (Directive (EU) 2023 / 1791), an adjustment is required. This adjustment is implemented through the gap-filling methodology.

The gap-filling methodology ensures alignment with EU policy targets while preserving the integrity of Member State contributions. It represents a controlled transformation of the NT dataset into a policy-compliant scenario (NT+), in line with the ACER Scenario Framework Guidelines.

For TYNDP 2026 Scenarios, a dedicated task force was established to assess alternative approaches to the methodology in the 2024 cycle. This taskforce presented the enhanced methodology outlined below to key stakeholders including SRG, EC and ACER, shown in Figure 17.

In the TYNDP 2026 Scenario, as in the 2024 cycle, the gap filling methodology was applied selectively:

This represents an evolution from previous cycles, where adjustments were applied more broadly. The methodology includes all energy carriers eligible for FEC reduction, with important exclusions.

These exclusions reflect recommendations from the Stakeholder Reference Group (SRG).

Gap identification is performed by comparing FEC from the NT data collection to EU and national FEC targets (see reference in previous subchapter). Where the NT exceeds the target, the difference defines the gap, which is quantified at member state level.

The methodology follows a structured logic:

The methodology aims to reduce final energy consumption by targeting the most emission-intensive energy carriers.

Sequential reduction approach

Fossil fuels are reduced in order of their greenhouse gas emission intensity:

Reduction is applied sequentially until the EC’s national FEC targets are met.

In practice methane remains available as a reduction option. However, for TYNDP 2026, reductions in coal and oil were sufficient to meet targets, and methane reductions were not required.

Proportional and sectoral allocation

Within each member state, reductions are distributed proportionally across sectors, maintaining the relative structure of energy consumption.

To avoid unrealistic results, the methodology incorporates constraints:

This constraint approximates the real world behaviour observed in energy transitions, where phase-out processes occur progressively rather than instantaneously.

The gap filling methodology is anchored to 2030 targets but applied consistently across all time horizons (2035, 2040, 2050).

The 2030 national FEC targets act as a ceiling constraint, ensuring that Final energy Consumption does not increase beyond 2030 levels and decarbonisation trajectories remain consistent over time.

The application of gap filling is guided by the following principles:

Pragmatism and feasibility: uses a simplified approach to ensure timely delivery of the TYNDP cycle.