Green roofs and climate resilience in The Hague

Abstract

Due to climate change, cities are expected to become subject to increasingly intense heat waves and precipitation. This calls for them to become more resilient towards such fluctuations. Green infrastructure is increasingly acknowledged as a means to enhance climate resilience, but cities – especially city centres – often lack the necessary space for realising such infrastructure. That is why green, vegetated roofs are frequently promoted as a potential solution for this spatial problem. This is also the case in the city of The Hague. In this municipality, green roof development has been stimulated for years with subsidies to increase the resilience towards the urban heat island effect (UHI) and stormwater flooding (SWF).

But while there is consensus within the municipality that more green roofs should be realised, no clear, quantifiable targets are set to achieve specific resilience goals. In part, this is because the potential benefits of green roofs have not been quantified at the city scale. And while most local benefits of green roofs are well known, downsides, costs and the barriers to implementation are not well understood.

The goal of this study is to examine the extent to which green roofs can increase climate change resilience in The Hague. In order to view this matter from complementing perspectives, three methods are used to answer five sub-questions. These methods are spatial analysis, financial cost-benefit analysis and stakeholder interviews.

In conclusion, large scale realisation of extensive green roofs is likely to have a positive effect on climate resilience in The Hague. These effects are significant at the city scale if green roofs are realised in large quantities, but they will likely not lead to easily noticeable results for the average citizen on the street. Substantial economic, political, legal and social barriers need to be overcome to implement green roofs at city scale for public environmental benefits. Several areas in the city do however hold notable potential to use its roof space for increased climate resilience.