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Good practice Imported

Green Million — Wieliczka's Proportional-Algorithm Participatory Budget (Method of Equal Shares)

Poland · Wieliczka · See the Poland profile

Evidence: Quasi-experimental Top 6% 87/100 · Ask Evidence Copilot about this practice

Wieliczka's 2023 'Green Million' pilot allocated a PLN 1,000,000 citizen budget using the Method of Equal Shares, a proportional algorithm from University of Warsaw researchers, cutting voter exclusion from 28% to 18% versus the town's prior standard-voting method.

PLN 1,000,000 (~EUR 220,000)
Budget allocated
6586
Residents who voted
64
Projects submitted
30
Winning projects selected under MES
PLN 995,079
Value of funded projects
2
Projects that would have won under the prior standard rule
28 %
Voters receiving none of their preferred projects, prior method
18 %
Voters receiving none of their preferred projects, under MES
~10 %
Rise in average voter satisfaction under MES
6.1 km
Maximum distance to nearest funded project, prior method
3.4 km
Maximum distance to nearest funded project, under MES
Green Million — Wieliczka's Proportional-Algorithm Participatory Budget (Method of Equal Shares)

Details

Maturity
Pilot
Promoter
Gmina Wieliczka (Wieliczka Municipality), with University of Warsaw's PRO-DEMOCRATIC project
Period
2023 (Zielony Milion pilot election)
Region (NUTS)
PL21
Keywords
participatory budgeting, civic tech, computational social choice, local government

Context

In April 2023, the Polish town of Wieliczka ran an experimental edition of its participatory budget, 'Zielony Milion' (Green Million), allocating PLN 1,000,000 among proposals submitted by residents.

Objectives

Instead of the town's usual plurality voting rule, the election tested the Method of Equal Shares (MES), a proportional budget-allocation algorithm developed by researchers including Prof. Piotr Skowron at the University of Warsaw's Faculty of Mathematics, Informatics and Mechanics under the ERC-funded PRO-DEMOCRATIC project.

Activities

6,586 residents voted across 64 submitted projects, and MES selected 30 winning projects worth PLN 995,079, compared with just two large projects that would have won under the previous standard rule.

Results

The share of voters who received none of their preferred projects fell from 28% under the old method to 18% under MES, average voter satisfaction rose by about 10%, and the maximum distance from a resident to their nearest funded project shrank from 6.1 km to 3.4 km, indicating better geographic fairness across the municipality.

Conclusions

The same algorithm has since been used in real participatory budgets in Swiecie (Poland), Aarau and Winterthur (Switzerland), and Assen (Netherlands), suggesting genuine transferability, though Wieliczka ran Green Million as a one-off experimental pilot alongside its regular participatory-budget cycle rather than replacing it, so it is not yet confirmed as the town's permanent method.

Implementation
Indicative cost
Low (< €50k)
Time to results
Short (< 1 year)
Staffing & skills
Delivered jointly by Gmina Wieliczka (municipal administration) and the University of Warsaw's ERC-funded PRO-DEMOCRATIC research team, led by Prof. Piotr Skowron.

Conditions for success

  • Partnership with an academic computational social choice research team to design and audit the algorithm.
  • Publication of anonymised election data for transparency via equalshares.net.
  • Running as an add-on pilot alongside the existing participatory budget process rather than a full replacement.

Common failure modes

  • No dedicated ongoing local governance body was established for the method beyond the one-off pilot.

Commonly funded by

Horizon Europe National / regional programmes

Indicative funding routes for practices of this type — always check each programme's current calls and eligibility rules.

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Data sources

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