URSI 100--Introduction to the City

Design with Nature


I.                   The Land

a. Water—Apparently tame creeks can flood their banks and threaten the lives of people near them. Usually this is due to rain, but not always.

                                                              i.      River profiles

1.      New—V-shaped profile

2.      Old—U-shaped profile, lateral cutting

                                                            ii.      Floodplain

1.      Fertile, stable soil deposited at bottom of river valley

2.      Affected by stormwater runoff:

a.      Groundcover

                                                                                                                                      i.      Forest absorbs 80%

                                                                                                                                    ii.      Farm field absorbs 40%

                                                                                                                                  iii.      Suburban development absorbs 60%

                                                                                                                                  iv.      Downtown absorbs 10% or less

b.      Time of year

c.       Soil type (sand vs. clay)

3.      Solutions:

a.      Channelization a, b, c, d, e, f

b.      Impoundment

c.       Avoidance a, b, c

b.      Soil & Subsurface Structures

                                                              i.      Strata (difference between limestone, shale, granite, sandstone)

                                                            ii.      Soils (see above)

                                                          iii.      Erosion & differential settling (e.g., “cut & fill”)

                                                          iv.      Groundwater and “aquifer recharge area”

c.       Earthquakes & Sinkholes

II.                The Climate

a.      Heat (city is a “heat island”)

b.      Wind (wind gradient)

c.       Dust

                                                              i.      dust dome

                                                            ii.      dust plume

d.      Rain

III.             Plant & Animal Life

a.      Commensalism

b.      Stress tolerance

                                                              i.      Air pollution

                                                            ii.      Drought

                                                          iii.      Contaminated soil

                                                          iv.      Contaminated water

c.       Urban plants

d.      Urban animals

IV.              Designing with Nature

a.      Key environmental concerns

                                                              i.      Keep rain out

                                                            ii.      Let light in (more in winter, less in summer)

                                                          iii.      Maintain internal temperature (keep heat out in summer, keep it in during summer)

                                                          iv.      Air circulation (less in winter)

b.      Topography--Preference varies by location

                                                              i.      Principles

1.      cold air pools at bottom of hill

2.      wind picks up at brow of hill

3.      hilltops are breezy

4.      mid-slope is warmest

                                                            ii.      Locations

1.      SSE slope for cool, temperate climates

2.      hilltop for hot, humid climates

3.      bottom of hill for hot, dry climates

c.       Solar control

                                                              i.      Shading—deep overhangs shade windows in summer but not in winter

                                                            ii.      Shape—greatest heat loss/gain is through roof (but ranch style gathers most breezes)

                                                          iii.      Materials—mass can absorb solar gain

d.      Air Motion

                                                              i.      Windbreaks—obstruct or channel prevailing wind

                                                            ii.      Landscaping

                                                          iii.      Windows—high inlet, low narrow outlet

e.      Temperature Control

                                                              i.      Prevent heat transfers

1.      insulation

2.      thermal curtains

3.      air-lock foyers

                                                            ii.      Heatsink—thermal mass

                                                          iii.      Solar collecto

1.      windows & roof collectors

2.      active vs. passive solar design

                                                          iv.      Example

1.      Wind towers a, b, c

2.      Earth-sheltered design

3.      Sound barriers



2003 A.J.Filipovitch
Revised 1 January 06