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7.2. Perimeter Block

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(Weitergeleitet von Perimeter Block)

Within the Small Blocks, buildings must be organized in relation to outdoor spaces for various functions.


07 2 01 Perimeter Blocks.jpg


Problem-statement: Within a block there is a need for outdoor space which is connected to the buildings, but not to the street.


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Discussion: Residences require outdoor space for recreation, for gardening, for parking and other needs. Commercial users also need outdoor space for utilitarian functions and service access. If this space is between the building and the street, it will cut the building off, and probably damage the experience of walking on the street. Putting it behind, inside the block and with buildings forming a perimeter, solves this problem, and offers other advantages.


The perimeter block arose independently in different civilizations over millennia as a naturally economical and practical urban typology. One important advantage is that buildings benefit from proximity to the walkable streetscape, and at the same time get ample light and adjacent private outdoor space in the quieter and more secluded interiors of the blocks.¹ Another benefit is that the perimeter block saves energy by clustering the buildings along the perimeter, and by facilitating a low-tech passive solar orientation, especially when exploiting deciduous trees and other near-ground benefits.² In addition, enclosing a gradient of small private gardens, parking courts and utilitarian spaces in the rear keeps the street intact for more public uses, and helps to frame more active, better-quality streetscapes.


Nevertheless, perimeter blocks fell into disfavor by industrial-modernist planners, who favored a very different typology: the apartment “slab” tower set in a large, undifferentiated green space. From an urban point of view, this is exactly the wrong geometry: the seldom-used green space is outside, separating buildings from streets and creating amorphous, unwalkable and often dangerous zones that Jane Jacobs memorably called “project prairies.”3


This contradiction is due to a misunderstanding of human psychology, which requires comfortable space to be defined by boundaries, and not left too open. It is also at the heart of the switch from traditional design — where buildings help to define urban space — to using open space instead to define a stand-alone building.


A perimeter block has the right sequence of public and private space: well-activated streets with close-grained private spaces in tight spacing; buildings that look out onto the streets; and then private outdoor space for gardening or utilitarian uses. Parks are where they should be: frequently distributed in lively locations. The entire perimeter block structure facilitates a greater mix of uses and grain of streetscape.⁴


07 2 02 Perimeter Blocks.jpg
A very flexible perimeter block with a mix of uses, as proposed by the UK’s Urban Task Force (1999).


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Therefore:

Place the bulk of building mass at the perimeter of the blocks, leaving the interior for outdoor space to serve the adjacent occupants, accommodating recreation, gardening, parking, service and other functions.


07 2 03 Perimeter Blocks.jpg


Use the Perimeter Building pattern at the edges of the blocks. Use Layered Zones and careful transitions from public to semi-private to private, and again to semi-private in the courtyards.




¹ One of the most thorough discussions of the perimeter block and its benefits is in Carmona, M., Heath, T., Oc, T., & Tiesdell, S. (2012). Public Places-Urban Spaces. London: Routledge.


² See for example Vartholomaios, A. (2015). The residential solar block envelope: A method for enabling the development of compact urban blocks with high passive solar potential. Energy and Buildings, 99, 303-312.


³ There has been much debate and research on the safety of such spaces. The architect Oscar Newman famously argued for “defensible space” rather than open park-like spaces. UCL’s Bill Hillier presented evidence that the picture is more complex, and that an overriding problem is the lack of “co-presence” of others and natural surveillance from buildings. See for example Hillier, B., & Sahbaz, O. (2008). An evidence-based approach to crime and urban design. London: Bartlett School of Graduates Studies, University College London.


⁴ Urban Task Force (1999). Towards an Urban Renaissance. London: Routledge.


Image: Kaspars Upmanis via Unsplash



SECTION I:

PATTERNS OF SCALE


1. REGIONAL PATTERNS

Define the large-scale spatial organization…

1.1. POLYCENTRIC REGION

1.2. BLUE-GREEN NETWORK

1.3. MOBILITY CORRIDOR

1.4. 400M THROUGH STREET NETWORK

2. URBAN PATTERNS

Establish essential urban characteristics…

2.1. WALKABLE MULTI-MOBILITY

2.2. LEVEL CITY

2.3. PUBLIC SPACE SYSTEM

2.4. BIOPHILIC URBANISM

3. STREET PATTERNS

Identify and allocate street types…

3.1.URBAN GREENWAY

3.2. MULTI-WAY BOULEVARD

3.3. AVENUE

3.4. SHARED SPACE LANE

4. NEIGHBORHOOD PATTERNS

Define neighborhood-scale elements…

4.1. STREET AS CENTER

4.2. PEDESTRIAN SANCTUARY

4.3. NEIGHBORHOOD SQUARE

4.4. NEIGHBORHOOD PARK

5. SPECIAL USE PATTERNS

Integrate unique urban elements with care…

5.1. SCHOOL CAMPUS

5.2. MARKET CENTER

5.3. INDUSTRIAL AREA

5.4. HOSPITAL

6. PUBLIC SPACE PATTERNS

Establish the character of the crucial public realm…

6.1. PLACE NETWORK

6.2. WALKABLE STREETSCAPE

6.3. MOVABLE SEATING

6.4. CAPILLARY PATHWAY

7. BLOCK AND PLOT PATTERNS

Lay out the detailed structure of property lines…

7.1. SMALL BLOCKS

7.2. PERIMETER BLOCK

7.3. SMALL PLOTS

7.4. MID-BLOCK ALLEY

8. STREETSCAPE PATTERNS

Configure the street as a welcoming place…

8.1. STREET AS ROOM

8.2. TERMINATED VISTA

8.3. STREET TREES

8.4. STREET FURNISHINGS

9. BUILDING PATTERNS

Lay out appropriate urban buildings…

9.1. PERIMETER BUILDING

9.2. ARCADE BUILDING

9.3. COURTYARD BUILDING

9.4. ROW BUILDING

10. BUILDING EDGE PATTERNS

Create interior and exterior connectivity…

10.1. INDOOR-OUTDOOR AMBIGUITY

10.2. CIRCULATION NETWORK

10.3. LAYERED ZONES

10.4. PASSAGEWAY VIEW



SECTION II:

PATTERNS OF MULTIPLE SCALE


11. GEOMETRIC PATTERNS

Build in coherent geometries at all scales…

11.1. LOCAL SYMMETRY

11.2. SMALL GROUPS OF ELEMENTS

11.3. FRACTAL PATTERN

11.4. FRAMING

12. AFFORDANCE PATTERNS

Build in user capacity to shape the environment…

12.1. HANDLES

12.2. CO-PRODUCTION

12.3. FRIENDLY SURFACES

12.4. MALLEABILITY

13. RETROFIT PATTERNS

Revitalize and improve existing urban assets …

13.1. SLUM UPGRADE

13.2. SPRAWL RETROFIT

13.3. URBAN REGENERATION

13.4. URBAN CONSOLIDATION

14. INFORMAL GROWTH PATTERNS

Accommodate “bottom-up” urban growth…

14.1. LAND TENURE

14.2. UTILITIES FIRST

14.3. DATA WITH THE PEOPLE

14.4. INCREMENTAL SELF-BUILD

15. CONSTRUCTION PATTERNS

Use the building process to enrich the result…

15.1. DESIGN-BUILD ADAPTATION

15.2. HUMAN-SCALE DETAIL

15.3. CONSTRUCTION ORNAMENT

15.4. COMPLEX MATERIALS



SECTION III:

PATTERNS OF PROCESS


16. IMPLEMENTATION TOOL PATTERNS

Use tools to achieve successful results…

16.1. FORM-BASED CODE

16.2. ENTITLEMENT STREAMLINING

16.3. NEIGHBORHOOD PLANNING CENTER

16.4. COMMUNITY MOCKUP

17. PROJECT ECONOMICS PATTERNS

Create flows of money that support urban quality…

17.1. TAX-INCREMENT FINANCING

17.2. LAND VALUE CAPTURE

17.3. EXTERNALITY VALUATION

17.4. ECONOMIES OF PLACE AND DIFFERENTIATION

18. PLACE GOVERNANCE PATTERNS

Processes for making and managing places…

18.1. SUBSIDIARITY

18.2. POLYCENTRIC GOVERNANCE

18.3. PUBLIC-PRIVATE PLACE MANAGEMENT

18.4. INFORMAL STEWARDSHIP

19. AFFORDABILITY PATTERNS

Build in affordability for all incomes…

19.1. INTEGRATED AFFORDABILITY

19.2. COMMUNITY LAND TRUST

19.3. MULTI-FAMILY INFILL

19.4. SPECULATION TAX

20. NEW TECHNOLOGY PATTERNS

Integrate new systems without damaging old ones…

20.1. SMART AV SYSTEM

20.2. RESPONSIVE TRANSPORTATION NETWORK COMPANY

20.3. AUGMENTED REALITY DESIGN

20.4. CITIZEN DATA