1.12 adapting the existing - retrofitting buildings for flood risk rotterdam & new york...
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Adapting the existing Retrofitting buildings for flood risk Rotterdam and New York
Presentation CAMINO Conference Antwerp, March 24 2015 Peter van Veelen Urban planner City of Rotterdam PhD researcher TU Delft Urbanism
The existing is vulnerable
Manhattan
Jersey City Brooklyn
Jersey Coast
Bridgeport
Long Island
Challenge: Retrofit flood resilience into existing building stock
• What adaptive measures and policies are effective? • How can we incorporate adaptation into processes of
urban development and management?
• What pathways to resilience provide flexibility and efficiency in the long run?
Flood risk Noordereiland Flood risk
Vulnerability of sewer system
Vulnerability of urban infrastructure
Basement appartment elevated first floor elevated social housing
Building typology
Current policy: living with water
Pictures: DSA Rotterdam
3,00 m + NAP
25/50 year flood
10 year flood in 2050
Annual flood 2100
3,45 m + NAP (4000 year flood)
1000 year flood in 2050 or 500 year flood in 2100
foto: DSA Rotterdam
Dry proofing
Source: Deltares
Sea level rise years from now
Effectiveness of measures
Develop adaptation pathways based on combinations of measures
Develop adaptation pathways based on combinations of measures
Possible adaptation pathway Noordereiland: Dry-proofing buildings 20-40 yrs.
Elevated boulevard 35 – 75 yrs. or: temporary flood defences >100 y.
Source: Deltares
Using urban dynamics
Social housing Annual building stock refurbishing rates: 3%-5% (20-35 year cycle) Average investment : € 23.000 Annual redevelopment rate: 1% (100 year cycle) Source: annual reports of social housing corporation (www.aedes.nl)
Privately owned buildings Planned maintenance cycle: 20 year cycle Large-scale renovation cycle 30-40 year cycle
Adaptation the existing housing stock requires at least 20 – 40 year
New York - Red Hook
Picture: Vin Crosbie
Demountable flood wall flood resilient architecture elevating houses
Current policy: building level adaptation
Flood risk
Less than 30 % of the building stock has a first floor above the required flood elevation level
Historical waterfront Elevated Residential buildings
Building typology
Wet proofing existing building
Filling in all below grade levels
Wet flood proofing all below BFE levels
Relocate all mechanical systems
Relocation of lost floor area Within the zoning envelope
type Compensation Adaptation options
NFIP premium reduction
# buildings
Wood frame detached
Elevate building full 6 (1%)
Brick stone and first floor above BFE
Plot is overbuilt or no space available in building envelope
Wet proof mechanical equipment
partial 93 (18%)
Space available in building envelope
fill all below grade spaces and wet proof all below BFE uses
full 61 (11%)
Brick stone and first floor below BFE
Plot overbuilt or no room in building envelope
Wet proof mechanical equipment
Almost none
158 (30%)
Space available in building envelope
fill all below grade spaces and wet proof all below BFE uses
full 208 (40%)
More than 50 % of the buildings can be brought up to full flood resilience requirements Only 50% of these building plots have opportunity to compensate the loss of space
Using urban dynamics
Brooklyn: Annual renovation rate: 0.4% (250 year cycle) Annual redevelopment rate: 0.35% (285 year cycle) District 6 (including Red Hook): Annual renovation rate: 2% (50 year cycle) Annual redevelopment rate: 0.2% (500 year cycle) Source: NYU Furman Center, 2014
Adaptation the existing housing stock requires at least 50 years
There is little potential to build resilience from household redevelopment or renovation within an acceptable timeframe (Sea level rise exceed the speed of retrofitting). Need to develop new complementary policies and regulative instruments that support easy-to-implement building-level resilience. District-wide solutions are effective to reduce overall flood damages and disruption but also need a considerable amount of planning and implementation time. Building level adaptation may be effective “to buy time”.
Conclusions
