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
• Optimal energy performance factors
Roof reflectivity (albedo) (+)
Existing insulation
Roof surface temp (-)
Plants with a high leaf area index
Heat flux (-)
Optimally thick substrate
Daily indoor temp fluctuations (-)
Low moisture content
Lower energy consumption
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: • Policy Perspective:
Intensive roofs better for:
Energy performance
Reducing runoff
Biodiversity
Urban heat island
Extensive still provide benefits, just not
to same degree
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