(Up)lifting the ground level: Recreational green rooftops as integrated part of the cities green infrastructure

Many large cities in the world have an unhealthy stressful urban climate: air pollution, lack of water retention, lack of biodiversity, urban heat island effects, etc. There is also a lack of space in the urban environment and predictions are that urbanisation and densification will increase (United Nations, 2007). Urban green is regarded as big part of the solution for the environmental challenges that cities are facing. Ecosystem services, (Bolund & Hunhammar, 1999) in cities should be planned for. Physical needs, security of existence, social and psychological needs can all benefit from green interventions (Hop & Hiemstra, 2013). Therefore, it is very important that local governments have ambitious green policies. The challenge in a densified city is space, where new dwellings need to be built, which leaves almost no space for green development. However, since the 1980s rooftop green was introduced. Projects were developed which resulted in beautiful green roofscapes. There are some critical remarks though: First, they primarily occur in the private sector. Second, public green roofs are often unknown by citizens, as they are hardly seen from ground level and often have bad accessibility. Since mid 2000’s, green façades began to emerge and green architecture became a fact. The advantages of green façades, in contrast with green roofs, is that they are visible from the street level. However, one cannot walk through a green façade. The third problem of green vertical and rooftop interventions is that they are implemented on a small scale scattered all over, with little to no interaction with the ground level. The effects of those green interventions are still very local, many potential synergies are unused.Green roofs and façades are mainly architectural projects and are connected to the isolation of the building. There is not enough attention for this type of green interventions yet from a landscape architectural point of view. This research shows an exploration of how city green can be optimized by integrating the facade-and rooftop green into the neighbourhood landscape. Rotterdam, the Netherlands, will be the main focus due to the many green roof interventions and number of flat roofs. The results show a stepwise approach how an existing city can transform into a biophilic one. Rooftop and facade green can be an extension of the ground level landscape and together form a new green urban landscape. To integrate the surrounding landscape into the city, requirements for new developments are set regarding historical structures, view lines, native species, etc. The city becomes part of the ‘natural’ landscape again. So there is "daily human contact with nature as well as the many environmental and economic values provided by nature and natural systems" (Beatley, 2011).Architecture, Urbanism and Building Sciences | Landscape Architectur