Intervention record · CHANGE4PLANET

The intervention

TIMELINE

WHAT WAS DEPLOYED

Since 2005 the City of Zurich has required recycled concrete, so far as technically possible, in every building it constructs [1][4]. The specification requires a minimum of 25 percent recycled aggregates in concrete in line with SN EN 206:2013 and SIA 2030, with RC-C quality (aggregate from crushed concrete demolition) as the minimum and RC-M quality (aggregate from mixed mineral demolition) where technically possible, aiming for a 25 to 50 percent minimum range [1][2]. The mandate followed a 2002 demonstration: a new school built with 80 percent recycled aggregates in partnership with a local producer, costing about EUR 78 million [1]. In 2013 (2015 per the city's current page) the city added a requirement for low-carbon CEM III/B cement, which replaces 66 to 80 percent of clinker with blast-furnace slag [1][4][6]. By 2019, around 90 percent of the concrete used in city public buildings was recycled concrete containing up to 50 percent recycled aggregates, a building could be made with up to 98 percent recycled concrete, and approximately 17,000 m3 of virgin materials and landfill space had been spared [1]. Over 2016 to 2021 the city consumed about 31,900 m3 of concrete per year, of which about 19,100 m3 (around two thirds) used CEM III/B, reaching approximately 80 percent from 2020 and avoiding about 7,430 tonnes of CO2 over the six years [1]. Recycled concrete cost the same or slightly less than virgin concrete (about EUR 178 per m3 in 2019) [1]. Supply followed demand: 8 to 10 local recycled concrete suppliers existed by the end of the 2000s and recent private buildings reach up to 50 percent recycled aggregates [1]. Industry reporting documents the spread beyond city ownership: 90 percent recycled concrete in an airport car park (13,050 m3 total) and about 80,000 m3 of recycled concrete on the Europaallee development, 2010 to 2015 [7].

HOW IT WORKS

Physical: recycled concrete (RC-Beton) is concrete with at least 25 percent by mass recycled aggregate [2][5]. RC-C concrete uses aggregate from processed concrete demolition (the city's reference mix: 50 percent recycled aggregate); RC-M concrete contains mixed-demolition granulate including brick and sand-lime masonry (reference mix: 25 percent mixed granulate of 40 percent concrete-derived and 60 percent masonry-derived grains, per SN EN 933-11) [2]. CEM III/B cement replaces 66 to 80 percent of clinker with blast-furnace slag; clinker production emits about 680 kg CO2 per tonne of cement, about 250 kg CO2 per tonne of concrete [1][2]. Recycled concrete is suitable for most building applications including exposed concrete and waterproof basements; as of 2017 it was not used for frost and de-icing salt exposure or precast elements, and CEM III/B cures more slowly, needing longer formwork stripping times and care at low temperatures [2]. Administrative: the Amt fuer Hochbauten writes binding concrete requirements into tenders for all city building projects and its engineering unit reviews offers [1][2][5]. The city built acceptance deliberately: demonstration buildings from 2002, a published fact sheet, an online concrete-type environmental calculator, and a 2017 mock-up wall comparing aggregate and cement types and surface treatments side by side [1][2]. The city ran a standards dialogue with SIA from the 1990s so national standards (1994, revised 2010 and 2021) carried the practice [1]. Construction-program performance is reported publicly every two years under the 7 Meilenschritte controlling framework (city council resolution STRB 722/2014), covering all city projects above CHF 2 million [3].

The measurements

11 OUTCOMES

OUTCOMES

METRIC	VALUE	METHOD	MEASURED BY	INDEPENDENT	PERIOD	SRC
Share of concrete used in city public buildings that is recycled concrete	90 % of concrete, approximate, containing up to 50% recycled aggregates	City material accounting compiled for the European Commission GPP In Practice case study (Issue 88, May 2019), republished by Agora	City of Zurich, Building Surveyor's Office	○	by 2019	[1]
Virgin materials and landfill space spared by recycled concrete in buildings	17000 m3, approximate, cumulative	City figure reported in the EC GPP case study, republished by Agora and Bloomberg	City of Zurich	○	by 2019	[1]
Concrete consumed in city building projects	31900 m3 per year, average	City consumption records released in a documented interview with the Building Surveyor's Office (Armin Grieder, 29 September 2021)	City of Zurich	○	2016-2021	[1]
City concrete made with CEM III/B low-carbon cement	19100 m3 per year of about 31,900 m3 total, around two thirds on average; approximately 80% since 2020	Same city consumption records	City of Zurich	○	2016-2021	[1]
CO2 avoided through CEM III/B cement substitution (scope 3)	7430 tonnes CO2 over six years	City calculation from consumption records, published by Agora	City of Zurich	○	2016-2021	[1]
Greenhouse gas reduction per m3 of concrete from CEM III/B cement	25 % reduction versus conventional concrete with CEM II/B, approximate · baseline conventional concrete, primary aggregates with CEM II/B (2017 publication)	City-commissioned life cycle assessment (Betonsortenrechner background study) published in the Beton konkret fact sheet	Consultants for the Amt fuer Hochbauten	○	2017	[2]
Overall environmental burden per m3 (Swiss eco-points, UBP), recycled aggregates plus CEM III/B versus primary aggregates plus CEM II/B	>10 % reduction · baseline conventional concrete, primary aggregates with CEM II/B (2017 publication)	Same city-commissioned life cycle assessment	Consultants for the Amt fuer Hochbauten	○	2017	[2]
Price of recycled concrete relative to virgin concrete	178 EUR per m3 in 2019; same price or slightly cheaper than virgin concrete	Market price reported in the EC GPP case study, republished by Agora; corroborated as roughly equal by Bloomberg [6]	City of Zurich / European Commission	○	2019	[1]
Local recycled concrete suppliers competing for city contracts	8-10 suppliers · baseline one partner producer at the 2002 pilot (2002)	Market development reported in the EC GPP case study, republished by Agora	City of Zurich	○	by the end of the 2000s	[1]
Recycled aggregate share achieved in recent private-sector buildings	up to 50 % of aggregates	Reported in the EC GPP case study, republished by Agora	City of Zurich	○	by 2019	[1]
Recycled concrete share, Kunsthaus Zurich extension	98 % of concrete; all in-situ concrete specified as RC-C with CEM III/B per the city's 2017 fact sheet [2]; about 20,000 m3 of recycled concrete per industry reporting [7]	Project figure reported by the city, republished by Bloomberg	City of Zurich / project team	○	2020-2021	[6]

● independently measured○ operator-reported· not stated in any source

COST BASIS

CAPITAL: not published
OPERATING: not published
PER UNIT: 178 EUR per m3 of concrete, 2019 market level; recycled concrete was the same price or slightly cheaper than virgin concrete [1]
FUNDING: 1

Scale context: the city had a public procurement budget of EUR 1.8 billion in 2019 and spent EUR 370 million on new public buildings, of which 15 to 25 percent (EUR 55 to 90 million) went to structural work including the concrete shell; in 2021 the city spent EUR 504 million on refurbished and new buildings [1]. Price parity mechanism: the saving from avoided virgin material and landfill disposal is roughly offset by the higher energy consumption of recycled concrete production [1]. The city's 2017 fact sheet states recycled concrete tends to be cheaper than primary concrete and advises checking offers for a cost advantage [2].

The assessment

PRECONDITIONS

A dense, constant local stream of construction and demolition waste: recycled concrete is only worth using when available within about 25 km of the construction site, which holds throughout the greater Zurich area [1][2]
Mandatory high-quality sorting of construction materials at demolition sites, required by the city from the 1990s, a practice already mandatory in some EU countries [1]
National standards recognizing recycled concrete so specifiers can call it up (Swiss standards from 1994, revised 2010 and 2021; SIA 2030 and SN EN 206:2013) [1][2]
A public building program large enough to anchor supplier investment: EUR 55 to 90 million per year of structural work created a demand suppliers competed for [1]
In-house engineering capacity to write binding concrete specifications and review offers (Fachstelle for engineering and sustainable construction) [2][5]
Deliberate acceptance work with architects and builders: demonstration buildings, a published fact sheet, an environmental calculator and a physical mock-up wall comparing concrete types [1][2]
For the cement component: tolerance in the construction program for slower CEM III/B curing, longer formwork stripping times, and restrictions on pumped concrete and low-temperature exposed concrete [2]
A market price environment where avoided landfill and virgin material costs offset recycling energy, keeping recycled concrete at or below the price of virgin concrete [1][2]

OPERATOR HINDSIGHT

Stated in the sources. The city's building surveyor's office named awareness as the limiting factor in 2021: "The biggest obstacle to a more widespread use of recycled concrete is awareness" (Armin Grieder), noting architects and engineers wrongly assume extra effort [6]. The city's current page states that broader knowledge and competence are still needed across the industry [5]. The 2017 fact sheet records the applications then still closed to recycled material: special concretes for frost and de-icing salt exposure and precast elements, for lack of experience [2]. Agora's assessment argues composition-based cement standards restrict innovation and should move to performance-based standards, the route Zurich pushed nationally through SIA revisions [1]. The city has since extended the approach to piloting the reuse of whole building parts, with catalogues of components from buildings slated for demolition [1].

TRANSFERABILITY ASSESSMENT

AXIS	SCORE	RATIONALE
CAPITAL INTENSITY	●●	A specification inside the routine building budget: recycled concrete cost the same or slightly less than virgin concrete (about EUR 178 per m3 in 2019), so no capital program was needed [1][2].
GOVERNANCE DEPENDENCY	●●	Implemented through the city's own building specifications and tender requirements as building owner, under existing procurement powers; the SIA standards dialogue supported adoption but the mandate itself needed no new legislation [1].
ENVIRONMENTAL SPECIFICITY	●○	Requires a dense local demolition-waste stream, with the material available within about 25 km of the construction site, the stated energy break-even radius; CEM III/B is constrained for pumped concrete and low-temperature exposed work [1][2].
SKILLS AND MAINTENANCE	●○	Specifying sits within normal procurement, but the documented uptake relied on a dedicated engineering unit, demonstration buildings and a mock-up wall to build supplier and architect competence, and the city still reports an industry-wide knowledge gap [1][2][5].
FUNDING REPEATABILITY	●●	Recurrent by construction: the requirement rides the ordinary building investment budget (EUR 370 million on new public buildings in 2019) at price parity [1].
POLITICAL DURABILITY	●●	In force continuously since 2005 across successive city administrations, extended with the cement requirement in 2013/2015 and restated as current practice on the city's pages as of 2026 [1][4][5].

TOTAL 10/12 · T1

POLITICAL TEST

The requirement has been in force for 21 years across successive elected city administrations: piloted 2002, mandated 2005, extended with the low-carbon cement requirement in 2013 (2015 per the city's current page), and carried into the city's 2022 decision to become climate neutral by 2040 (2035 for the administration) [1][4][6]. The city's own public pages state the practice as current as of August 2026 [4][5]. The mandate also survived a standards environment shift: Swiss recycled concrete standards were revised in 2010 and 2021 with the city participating, and since February 2025 SN/EN 206 allows reduced minimum cement quantities [1][5]. No source documents any attempt to repeal the requirement.

The file

7 SOURCES

SOURCES

[1] case_study · Recycled Concrete and Low-Carbon Cement (Success Stories, Switzerland, Buildings and Industry), doc. 282/03-DO-2022/EN · Agora Energy Transition (Agora Energiewende) · 2022-12 · en · PRIMARY · INDEPENDENT · www.agora-energiewende.org Full 7-page PDF fetched and read. Independent think-tank documentation carrying original sourced interviews with City of Zurich officials (Armin Grieder, 29 September 2021; Philipp Noger, 11 June 2021), including the otherwise unpublished 2016-2021 concrete and cement consumption figures. Its uptake figures (90 percent share, 17,000 m3, 8-10 suppliers, EUR 178 per m3, 98 percent building) are attributed to the European Commission GPP In Practice Issue 88 case study (May 2019), which could not be retrieved directly (see confidence notes).
[2] operator_publication · Beton konkret: Musterwand Recyclingbeton (Fachbeitraege No. 1) · City of Zurich, Amt fuer Hochbauten, Fachstelle Nachhaltiges Bauen and Fachstelle Ingenieurwesen (named participants include Philipp Hubler, Philipp Noger, Simon Kraus) · Stadt Zuerich, Amt fuer Hochbauten · 2017-06 · de · PRIMARY · www.stadt-zuerich.ch Full 5-page PDF fetched and read in German. Operator fact sheet: RC-Beton definition (minimum 25 mass percent recycled aggregate per SIA 2030:2010 and SN EN 206:2013), RC-C and RC-M mix compositions, CEM III/B emission figures, environmental comparison chart from the city-commissioned Betonsortenrechner study, applications and limits, cost statement, and six named case buildings 2004-2020 with their concrete specifications.
[3] operator_report · 7 Meilenschritte zum umwelt- und energiegerechten Bauen: Jahresbericht 2017/2018 · Annette Aumann, Raffael Hegglin, Philipp Noger, Markus Simon, Thomas Kessler, Michael Poell, Annick Lalive d'Epinay, Markus Hilpert · Stadt Zuerich, Amt fuer Hochbauten · 2019-07 · de · PRIMARY · www.stadt-zuerich.ch Full 33-page PDF fetched and read in German. Establishes the biennial published controlling regime (STRB 722/2014, all projects above CHF 2 million, reporting at completion), documents the mock-up wall program, and records the Velostation Europaplatz (1,600 bicycle spaces) built with exclusively recycled concrete for its walls and decks.
[4] operator_webpage · Kreislaufwirtschaft (circular economy page) · Stadt Zuerich · accessed 2026-08-13 · de · PRIMARY · www.stadt-zuerich.ch Fetched and read 2026-08-13. Current operator statement that since 2005 all buildings constructed by the city are built as far as possible with recycled concrete, and since 2015 additionally with CO2-reduced cement. This page is the record's evidence that the mandate is current, and the source of the 2015 date for the cement requirement.
[5] operator_webpage · Recyclingbeton (Meilenschritt 4, intelligente Ressourcennutzung) · Stadt Zuerich · accessed 2026-08-13 · de · PRIMARY · www.stadt-zuerich.ch Fetched and read 2026-08-13. Current operator technical page: RC-Beton definition (minimum 25 mass percent recycled aggregate; RC-C and RC-M types), about 680 kg CO2 per tonne of cement, CEM III/B reduction of up to 35 percent, note that since February 2025 SN/EN 206 permits reduced minimum cement quantities, and the statement that more knowledge and competence are needed across the industry.
[6] news_article · How Zurich Blazed a Trail for Recycled Concrete · Corinne Gretler · Bloomberg CityLab · 2021-09-26 · en · INDEPENDENT · www.bloomberg.com Read in full via the nowcomment.com mirror (nowcomment.com/documents/294131); the Bloomberg original is paywalled and its URL slug is dated 2021-09-27 while the mirror states September 26, 2021. Independent journalism confirming the 2002 school (80 percent), the 2005 mandate, the 2013 cement requirement, the Kunsthaus extension at 98 percent, hospital and housing complexes at 95 percent, the 17,000 m3 figure, price parity, and the Grieder quote used in this record.
[7] industry_publication · Vorreiter im Bauen mit Recyclingbeton · BETONSUISSE Marketing AG · accessed 2026-08-13 · de · INDEPENDENT · www.betonsuisse.ch Fetched and read 2026-08-13; no publication date stated. Industry marketing body, independent of the city but promotional; used only for building-level volumes evidencing market spread: Schulhaus Leutschenbach about 6,750 m3 recycled concrete (75 percent of its concrete), Kunsthaus extension about 20,000 m3, Parkhaus C at Zurich Airport 90 percent of 13,050 m3, about 80,000 m3 across Europaallee fields C, E and H (2010-2015), Schulhaus Hardau 100 percent.

RECORD

PUBLISHED: 2026-08-13
LAST VERIFIED: 2026-08-13
REVIEW DUE: 2027-02-13
RUBRIC: v1.0
STATUS HISTORY: 2026-08-13 · operating · Record published.
LANGUAGE: The operator's primary sources (Beton konkret fact sheet, 7 Meilenschritte annual report, stadt-zuerich.ch pages) are German-language and were read in German; figures and quoted phrases were translated by the registry. The Agora study and Bloomberg article are English-language.
CONFIDENCE: Solid: the policy dates (2005 mandate, standards 1994/2010/2021), definitions (25 mass percent minimum, RC-C, RC-M, CEM III/B composition), the 2016-2021 consumption and CO2 figures (31,900 m3 per year, 19,100 m3 CEM III/B, 80 percent since 2020, 7,430 t CO2), the 2019 uptake figures (90 percent share, 17,000 m3 spared, EUR 178 per m3, 8-10 suppliers), and the named buildings were all read directly in the cited documents, not from abstracts. Thin or judgment-based: (a) the headline uptake figures originate in the European Commission GPP In Practice Issue 88 case study (May 2019), which could not be retrieved directly (the ec.europa.eu URL redirects to a CIRCABC application; two mirrors returned 403); those figures are cited here as republished, with attribution, by the Agora study [1], and the 17,000 m3 scope (buildings, cumulative to 2019) is not further specified there. (b) Sources disagree on when the low-carbon cement requirement began: 2013 per Agora and Bloomberg [1][6], 2015 per the city's current page [4]; both dates are retained and the discrepancy is unresolved. (c) The per-m3 CO2 reduction from CEM III/B is stated as about 25 percent in the 2017 fact sheet [2], 25 to 30 percent by Agora [1], and up to 35 percent on the city's current page [5]; the record's outcomes table uses the operator's published 2017 figure. (d) No independent audit of the city's material accounting exists in the fetched sources; all uptake outcomes are marked not independent and the record grades E3. (e) The Betonsuisse building volumes are industry-published without stated method. (f) The 90 percent and up-to-50-percent figures are shares at a point in time (by 2019), not a continuously monitored series; the city's controlling reports monitor energy milestones biennially but the fetched 2017/2018 report contains no recycled concrete share table. (g) population_served is null; no source publishes one. (h) Bloomberg's publication date differs by one day between the mirror text and the canonical URL slug. No figures were estimated or interpolated by the registry; all nulls reflect absence in sources.

CITE THIS RECORD

change4planet.org. C4P-CIR-0001: Recycled concrete procurement for public buildings, City of Zurich: minimum-content specification since 2005 with published uptake. Grades T1/E3 (rubric v1.0). Last verified 2026-08-13. https://change4planet.org/records/c4p-cir-0001-zurich-recycled-concrete