By the year 2025 Rotterdam aims to have halved its CO2 emissions; an ambitious plan that will require a revolutionary approach to urban areas. One proactive response to this challenge is an exploratory study of the Hart van Zuid area. An interdisciplinary team has investigated how to tackle CO2-issues in a structured way. This has resulted in the Rotterdam Energy Approach and Planning (REAP) methodology. REAP supports initial demand for energy, propagates the use of waste streams and advocates use of renewable energy sources to satisfy the remaining demand. REAP can be applied at all levels: individual buildings, clusters of buildings and even whole neighbourhoods. Applying REAP to the Hart van Zuid has shown that this existing area can become CO2 neutral. Best of all: REAP can be applied everywhere.

Work on a liveable low carbon city has often been approached in a technocratic way, not linking to other disciplines and urban practices at a large scale. This paper explores a stakeholder based urban agenda for a more liveable low carbon city by densifying and greening with the case study of Rotterdam inner city. Rotterdam presents a unique European case with a modernistic inner city. Like many North American cities, the inner city for a long time mainly served as a business or shopping district with few inhabitants and few synergetic links between flows, urban functions, and areas. In line with other cities, Rotterdam aims to reduce carbon emissions and provide a high quality of life. To address this, the hypothesis 'densifying and greening leads to a more sustainable inner city', was tested and applied with stakeholders using transition management combined with urban data, modelling, and design. With sustainability indicators, geographic information system (GIS) mapping, and urban models, a baseline study was completed and expected outcomes were described and, where possible, validated in reality. The outcomes confirmed the stated hypothesis and showed that linking design, GIS mapping, and city data to transition management proved successful.