A multicriteria index developed at the Data Science Laboratory of the Technical University of Crete by Dimitris Zopounidis, presented at 102nd EWG-MCDA at ETH Zurich organized by the Paul Scherrer Institut, finds substantial variation in sustainability performance across airports and over time.

Airports are usually judged by the numbers that are easiest to count: passengers, movements, revenue. It is a convenient measure and a misleading one. It rewards size, and it tells you almost nothing about whether an airport is managing its energy, water, emissions, infrastructure and workforce well.

A new framework presented last month at the 102nd Meeting of the EURO Working Group on Multiple Criteria Decision Aiding, hosted at ETH Zurich and organised by the Paul Scherrer Institute, sets out to close that gap.

The Airport Sustainability Performance Index (ASPI), developed at the Data Science Laboratory of the Technical University of Crete, applies multicriteria decision analysis to the 14 regional airports operated by Fraport Greece over the period 2018 to 2024.

What makes it different

ASPI is built on thirteen indicators organised into five dimensions: environmental, infrastructure, accessibility, socio-economic and operational. They cover carbon emissions, energy and water efficiency, terminal capacity, ground accessibility, employment stability, seasonality pressure and traffic composition.

The critical design choice is normalisation. Every indicator is expressed relative to passenger volume, and each is explicitly defined as either a benefit or a cost. This removes the scale bias that dominates conventional airport rankings. A small island airport is no longer penalised simply for being small, nor a large one rewarded for being large. The question the index asks is not how big an airport is, but how efficiently it operates for its size.

The aggregation is handled by PROMETHEE II, an outranking method that compares each airport against every other one, criterion by criterion, and builds a complete ranking from net preference flows. Gaussian preference functions are applied to the quantitative criteria, so that marginal differences are treated as noise rather than as genuine superiority.

Solving the weighting problem

Every composite index faces the same objection: who decided that the environment matters more than infrastructure, and by how much?

ASPI does not answer that question. It sidesteps it.

The framework runs the entire model through SMAA-2 (Stochastic Multicriteria Acceptability Analysis) using 100,000 scenarios with randomly generated criterion weights and preference parameters, constrained so that no dimension can fall below five percent. Instead of producing a ranking under one set of assumptions, it explores the whole space of defensible weightings.

The result is that an airport’s position is not an artefact of a particular weighting scheme. If it ranks well across most of that space, the position is robust. Results are reported both as median net flow scores and through the holistic acceptability index, and the two rankings agree closely. That agreement is the robustness check.

What the data show

Chania and Thessaloniki are the consistent performers, holding strong positions throughout the period.

Rhodes is the standout improver. It sits eleventh in 2018 and reaches first place by 2024.

Mytilene moves in the opposite direction. First for three consecutive years from 2018, tenth by 2024.

That contrast is the central finding. Forward-looking Kendall τ correlations between annual rankings average 0.32 for median net flows and 0.34 for the acceptability index. Consecutive years correlate reasonably, but the relationship decays quickly across longer horizons. In plain terms: being a sustainability leader this year says very little about where you will stand in five.

The intertemporal analysis also isolates the pandemic. Performance falls sharply in 2020 and recovers strongly from 2021 onwards, driven by gains in the environmental and accessibility dimensions. Infrastructure is the laggard, and the reason is structural rather than managerial. Terminal capacity at tourism-dependent island airports is sized for the July and August peak and underused for the rest of the year, and improving it requires capital investment over years, not operational adjustment over months.

Why it matters for the sector

For airport operators, the practical value is diagnostic. ASPI identifies which dimension is holding a given airport back, and whether its position is robust or fragile across different priority sets. For regulators and policymakers, it offers a longitudinal benchmarking framework adapted to the specific characteristics of regional, seasonal and island airports, rather than one imported from large hub operations.

It also complements rather than replaces existing schemes. Airport Carbon Accreditation certifies performance on a single dimension. ASPI ranks across five, with explicit treatment of uncertainty.

Next steps

The authors Dimitris Zopounidis and Professor Michalis Doumpos of the Technical University of Crete identify several directions for further work: incorporating economic criteria, investigating the internal and external drivers of sustainability improvement, engaging airport management and passengers directly in the preference elicitation, and comparing alternative multicriteria aggregation models.

The reception in Zurich, in a room of energy and environmental decision analysts from across Europe, suggested there is appetite for exactly this kind of framework. Whether Greek regional airports act on what it tells them is a separate question.

Beyond Greece

The framework itself is not specific to Greece. It is built on publicly reported environmental and operational data, which means it transfers to any airport network operated under a common reporting standard. Fraport’s German portfolio is the most obvious extension, given the identical reporting methodology, as are the Swiss, Spanish, Portuguese and Croatian networks, where seasonal and island-dominated traffic profiles resemble the Greek case closely. A cross-country application would allow the same question to be asked at European scale: whether sustainability leadership among regional airports is as unstable everywhere as it appears to be in Greece.