The Hidden Data Problem Draining Zurich's Digital Archives: Duplicate Images by the Numbers

Zurich's public-sector digital archives are carrying tens of thousands of duplicate image files, and the bill for storing them is growing. Across city departments, cantonal agencies, and university libraries, IT administrators have quietly flagged the problem for years. Now, with cloud storage costs rising and housing-crisis budget pressures forcing every department to justify its expenditure line by line, the numbers are finally getting attention at the management level.

The issue is not unique to Zurich, but the city's concentration of data-heavy institutions — from ETH Zurich's research image repositories to the Zentralbibliothek Zürich's digitisation projects along Zähringerplatz — gives the problem particular local weight. Digitisation efforts that accelerated during the pandemic years left many institutions holding multiple copies of the same scanned photograph, archival plate, or research graphic, stored under different file names across different servers.

What the Numbers Actually Show

Industry benchmarks from digital asset management consultancies suggest that duplicate files typically account for between 20 and 30 percent of total storage volume in large institutional archives. Applied to Zurich's context, that matters: ETH Zurich's library system alone managed over 90 petabytes of research data as of figures published in its 2024 annual report, spanning multiple storage tiers. Even if image duplicates represent only a fraction of that total, the redundancy compounds quickly when factored across the University of Zurich, the Stadt Zürich's own Stadtarchiv on Neumarkt, and the cantonal health and planning departments.

Storage costs in Switzerland run significantly higher than the European average. Enterprise-grade object storage from Swiss-based providers — a requirement for institutions handling sensitive or legally protected materials under cantonal data-protection rules — can cost anywhere from CHF 0.025 to CHF 0.05 per gigabyte per month, depending on contract scale and redundancy tier. A single institution sitting on 50 terabytes of unnecessary duplicates could be spending upward of CHF 15,000 per year on storage it does not need. Multiply that across a dozen major city and cantonal bodies, and the aggregate waste becomes a line item worth cutting.

The human cost compounds the infrastructure cost. IT staff at institutions in the Hochschulgebiet district — the dense cluster of university buildings between Rämistrasse and Gloriastrasse — report spending measurable portions of their working week manually reviewing and deduplicating image collections before major system migrations. Automated deduplication tools exist, but adoption has been inconsistent, partly because Swiss public procurement rules require competitive tendering processes that can stretch six months or longer for software contracts above certain thresholds.

Pressure to Act Is Building

The timing of this reckoning is not accidental. The UBS-Credit Suisse merger fallout has sharpened scrutiny of institutional efficiency across Switzerland's financial and public sectors alike, with cantonal governments under political pressure to demonstrate fiscal discipline. In Zurich's case, the city council approved a digital infrastructure audit framework in early 2025 as part of the broader Stadtentwicklung strategy, with results from the first audit cycle expected later this year.

Parallel pressure comes from the climate agenda. The City of Zurich's 2040 net-zero target, embedded in the Energierichtplan, explicitly includes reducing the energy footprint of municipal data infrastructure. Duplicate data means duplicate energy consumption in server rooms — a fact that has given IT efficiency arguments new political traction in a council chamber where climate votes carry weight.

For institutions looking to address the problem practically, the Stadt Zürich's IT coordination office has been piloting a shared deduplication protocol since March 2026, trialling hash-based image fingerprinting across three city departments. Early internal reviews, circulated to participating departments but not yet published, reportedly show storage reduction rates in the 18 to 24 percent range. If the pilot expands to cantonal level before the end of the year, it could serve as a model other Swiss cities — Geneva, Basel, Bern — have already asked to observe. The numbers, at least, make a compelling case for moving fast.