Building dwellings in greenfields instead of developing within-city transformation sites is more viable in terms of economic welfare. There are major differences between the sites examined, however, as a social cost-benefit analysis based on 18 exemplary sites in the Rotterdam urban region shows. The study was carried out in collaboration with LPBL and Atlas voor gemeenten.

The social cost-benefit analysis examined the pros and cons of within-city building versus building in greenfields and expressed them in monetary terms. This was the first analysis to include not only the financial balance but also almost all the ‘external effects’ and express them in monetary terms: the effects on demography, quality of life & security, mobility, nature and open spaces, as well the economic aspects of agglomerations, i.e. productivity, human capital and level of amenities.

The economic outcome is determined mainly by the cost of acquiring the land and making it suitable for building and occupation and of the house-building programme that can be carried out there. The benefits of housing are determined mainly by car and public transport access and proximity to urban centres with highly-educated people, employment and amenities. Also, the more people are currently botheredby unattractive within-city locations,, the greater the potential positive effects of developing them into housing areas.

The findings are specific to the Rotterdam region and the selected sites. One major advantage of within-city building as opposed to building in greenfields – i.e. higher returns – was found to be smaller in Rotterdam than many other cities. Although Rotterdam has a number of potentially valuable inner-city building sites, their value is diminished by the quality-of-life problems that Rotterdam still faces.