"City-zen deals with the development of the city of the future. The project has three major goals, 1- to realize more effective collaboration models and a methodology for development of smart cities, 2- to connect with industry, and have them develop technology to the benefit of smart cities and 3- to showcase to society ambitious pilot projects. Main idea for this project is that after successful implementations in topics such as district heating, energy grids, local energy generation, energy efficiency for housing, now it is time for the next big step: integrated flexible open infrastructures.The approach taken is the set-up of stakeholder teams in the demonstrator cities, to accelerate the realization of energy-efficient city development. This effort is supported by technology teams including industrial parties. Workshops aiming at decreasing the gap between innovation and implementation will be organized and knowledge-disclosing material will be developed by specialized working groups in retrofitting, smart grids, and heating and cooling. This approach holds for both technology and process improvement.The demonstrators in Amsterdam and Grenoble include retrofitting 105000 m2 of housing to levels down to 53 kWh/m2, showing average savings of the order of 80%. Furthermore they include fully-functional smart grid development, electricity storage demonstrators, free cooling schemes and district heating efficiency improvements.The City-zen project recognizes the key position of citizens, so ample attention is paid to dissemination and education of this group. Serious gaming is included as part of the work, as well as a roadshow bringing the results of the project right at the doorsteps of decision makers in other cities.Extensive monitoring of all buildings and installations is included.All demonstrators together have an estimated impact of 59000 tonne/year CO2 reduction. Amsterdam and Grenoble CO2 reduction goals for 2050 are 80% reduction."