Implementing Green Roof Technology: An Integrative Approach Towards Optimizing Social and Ecological Benefits Yanique Bedward Coosje Hammink Mihai Hopirtean Ole Johannsen Ariane Laporte-Bisquit Susan Rees Arielle Tozier de la Poterie 29 October 2010

Introduction to Green Roofs Intensive Extensive

Central Research Question How can green roofs benefit or hinder the cause for sustainability in the Watergraafsmeer (Amsterdam) area, and what obstacles, opportunities and uncertainties face the current situation in terms of both policy and technical considerations? Additionally, how can future research be best directed in order to fill knowledge gaps and to overcome the challenges of implementing and sustaining green roof proliferation in this area?

Chapter 2: What are the energy related benefits of green roofs and for which green roof design are these benefits maximized? Benefits Roof reflectivity (albedo) (+) Roof surface temp (-) Heat flux (-) Daily indoor temp fluctuations (-) Lower energy consumption Optimal energy performance factors Existing insulation Plants with a high leaf area index Optimally thick substrate Low moisture content Porous substrate Large roof-envelope ratio (semi-) intensive green roof

Chapter 3: Combining Green Roofs & Solar Technology Green roof systems combined with: Roof ponds (blue roofs) Solar photovoltaic systems Solar water heating systems Conclusions: Energy performance of blue roofs hasn’t been documented in the Netherlands Green roofs lead to lower surface temperatures of rooftops which can be Photovoltaic conversion efficiency can be enhanced by the presence of a green roof due to the a lower ambient temperature, however more research is required

Chapter 4: The role of green roofs in rainwater runoff management in urban areas Optimal design for reducing runoff: Deep substrate, rich in organic matter and minerals Dense and diverse vegetation cover Potential of blue roofs to reduce runoff? Integrating green roofs with other rainwater infrastructures? Water quality: Overall positive effect BUT risk of water pollution from fertilizers and nutrient enriched substrates

Chapter 5: Green Roofs, Biodiversity, & Urban Heat Island Intensive green roofs have a higher potential for biodiversity conservation/creation Proper management increases local pollinator diversity Green roofs probably contribute in a positive way to green-space networks and therefore to the overall urban ecology/biodiversity Green roofs can help to improve the air quality, reduce the “urban heat island effect”

Chapter 6: Market & Civil Society Stakeholders Market and Civil Society Governance Arrangements Obstacles and Opportunities Little official policy, much market power Utilize the power of market actors, official policy is necessary Carrot and Stick

Chapter 7: Green Roofs and the State: New Public Management New Public Management Market-based techniques Downsize state Green Roofs Government has steering function Market-oriented incentives Competition

Chapter 8: Policy Instruments & International Examples Examined policy instruments (theoretical) and how they are used around the world (practical) Policy instruments Direct financial incentives Indirect financial incentives Command & control Case Studies: Germany & Toronto No quick fixes Main conclusion: Need local data on which to base policies Outlined criteria on which policies could be evaluated

Integrated Conclusions Environmental Science Perspective: Intensive roofs better for: Energy performance Reducing runoff Biodiversity Urban heat island Extensive still provide benefits, just not to same degree Policy Perspective: Intensive roofs may be more difficult to adopt Cost, maintenance, expertise Extensive feasible alternative Easier to combine with other technology Currently a lack of vertical & horizontal coordination Need to explore applicability of policy instruments to local context

Research Action Plan Overall Conclusion: Need data 1) Experimental site to collect ecological, energy savings, and biodiversity data and to test combinations of different techonologies 2) Explore horizontal & vertical opportunities for coordination and cooperation between State, Market, Civil Society concerning green roofs 3) Using data from collecion sites, evaluate benefits and drawbacks of different policy instruments Select appropriate policy instruments for Amsterdam based on criteria outlined in chapter 8