Green roofs in temperate climate cities in Europe - An analysis of key decision factors

- Systematic analysis of factors relevant for green roof diffusion.
- Experts consider prospects for green roofs to be rather bright.
- Green roofs are likely to benefit from climate change adaptation and mitigation strategies.
- Dilemmatic incentive structures might prevent green roof diffusion.

This paper aims to identify and assess the main decision factors that are relevant for the diffusion of green roof technology in cities of temperate climate in Europe. A mixed design method was applied to identify relevant factors and to structure these along a Strengths, Weaknesses, Opportunities and Threats framework. The factors were subsequently assessed by a sample of green roof experts, using an Analytical Hierarchy Process. The results indicate that prospects for green roofs are in general rather bright, and that dissemination potential is substantial. Green roofs are particularly likely to benefit from climate change and respective counter-strategies, as they are seen as an adaptation and mitigation measure. However, current barriers to adoption need to be carefully considered. Especially the dilemmatic incentive structures, in that building owners bear most of the risks and potential disadvantages, while the public collectively benefits from green roof advantages, could be a major implementation barrier. Without supportive policies, green roofs are thus unlikely to move from niche to regime level in the near future.