URSI 100--Introduction to the City

Design with Nature

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

MSU