In the course of its existence, the IÖW has carried out more than 400 individual projects. The following institutions are either promoters or clients, amongst others:
Institutions of the German Federation
- Federal Ministry of Labour and Social Affairs (BMAS) | Berlin
- Federal Ministry of Education and Research (BMBF) | Bonn, Berlin
- Federal Ministry of Food, Agriculture and Consumer Protection (BMELV) | Berlin
- Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) | Bonn, Berlin
- Federal Ministry of Transport, Building and Urban Affairs (BMVBS) | Berlin
- Federal Ministry of Economics and Technology (BMWi) | Bonn, Berlin
- Federal Office for Building and Regional Planning (BBR) | Bonn
- Federal Agency for Nature Conservation (BfN) | Bonn
- Federal Institute for Risk Assessment (BfR) | Berlin
- Office of Technology Assessment at the German Parliament (TAB) | Berlin
- Council for Sustainable Development (RNE) | Berlin
- Federal Environment Agency (UBA) | Dessau
Institutions of the German States (Länder)
- Berlin Senate Department of Labour, Vocational Education and Women | Berlin
- Berlin Senate Department of Urban development | Berlin
- Berlin Senate Department for Economics and Technology | Berlin
- Hessen Ministry of economics, transportation, urban and regional development | Wiesbaden
- Hessen Ministry for Environment, Energy, Youth, Family and Health | Wiesbaden
- Schleswig-Holstein Ministry of Environment, Nature Conservation and Forests | Kiel
- North Rhine-Westphalian Ministry for Environment, Nature Conservation, Technology, Agriculture and Consumer Protection | Düsseldorf
- Ministry of Environment and Transportation Baden-Württemberg | Stuttgart
- Ministry of Economics Brandenburg | Potsdam
- North Rhine-Westphalian Ministry for Economy, Technology, Medium-sized Businesses and Transport | Düsseldorf
- Ministry of Regional Policy and Environment Sachsen-Anhalt | Magdeburg
- State Institute for Environment Hessen | Wiesbaden
- State Institute for Environmental Protection Baden-Württemberg | Karlsruhe
International Institutions
- United Nations Conference on Trade and Development (UNCTAD) | Genf
- United Nations Environment Programme (UNEP) | Paris
- Federal Office for the Environment FOEN Switzerland | Bern
- European Commission, different Directorate-Generals | Brussels
NGOs
- Bund für Umwelt und Naturschutz e.V. (BUND) | Berlin
- Bund Naturschutz in Bayern e.V. (BN) | Regensburg
- foodwatch e.V. | Berlin
- Greenpeace e.V. | Hamburg
- Naturschutzbund Deutschland e.V. (NABU) | Berlin
- Verbraucherzentrale Bundesverband e.V. (vzbv) | Berlin
- World Wide Fund For Nature Deutschland (WWF) | Frankfurt
Companies
- Bayer AG
- BSH Bosch und Siemens Hausgeräte GmbH
- Ciba-Geigy GmbH, Division Pharma
- Daimler Chrysler AG
- DEGUSSA
- dena - Deutsche Energie Agentur
- Deutsche Bahn AG
- Flughafen Frankfurt/Main AG
- Henkel KgaA
- Kraft Jacobs Suchard Deutschland
- Landesbank Baden-Württemberg (LBBW)
- Märkisches Landbrot GmbH
- Media Profil GmbH
- Miele & Cie. GmbH & Co
- MVV Energie AG
- Nature Pack, S.A., Spanien
- Ökobank e.G.
- Otto Versand AG
- Siemens AG
- Triumph International AG
- Vodafone Deutschland
- Volkswagen AG
- WELEDA AG
- YTONG AG
- CAPITAL Magazine
Other institutions
- Deutsche Bundesstiftung Umwelt (DBU) | Osnabrück (German Foundation for Environment)
- Study Commission "Schutz des Menschen und der Umwelt" | Deutscher Bundestag (German Parliament)
- Study Commission "Zukunft der Mobilität" | State of Nordrhine-Westfalia | Düsseldorft
- Study Commission "Zukunftsfähiges Berlin" | Abgeordnetenhaus Berlin (State Parliament of Berlin)
- Parliamentary Party Bündnis 90 / Die Grünen, German Bundestag | Bonn, Berlin
- Friedrich-Ebert-Stiftung e.V. | Bonn
- Gesellschaft für technische Zusammenarbeit (GTZ) | Eschborn (Society for technical cooperation)
- Germany's Public Services and Transport Workers' Union | Bonn
- Hans-Böckler-Stiftung (HBS) | Düsseldorf
- IHK Rhine-Neckar
- Landkreis Osnabrück
- Otto-foundation | Hamburg
- Raumordnungsverband Rhine-Neckar | Mannheim
- Stadt Heidelberg
- Stadt Mannheim
- Stadt Wuppertal
- Stadtwerke Augsburg
- Unternehmensvereinigung Solarwirtschaft e.V. (UVS) | Berlin
- Volkswagen-Stiftung | Hannover
- Institut für Organisationskommunikation (IFOK) | Bensheim
- Eco-Centre Northrhine-Westfalia | Hamm
- Wirtschaftsförderungs- und Regionalentwicklungsgesellschaft Flensburg/Schleswig mbH (WiREG) | Flensburg
- Social Science Research Center | Berlin
- VRD Energie Stiftung | Mannheim