Environmental Factors Flashcards
GRAVEL
well-drained, bears loads
2mm or larger
SAND
well-drained; can serve as foundation if graded
0.5-2mm
SILT
stable when dry, swells when frozen
0.002-0.5mm
CLAY
to stiff when dry and too plastic when wet
0.002 mm or smaller
Human comfort
winter
summer
humidity
63-71 degrees
66-75 degrees
30-60% is tolerable
75% or more is uncomfortable
Wind speed unnoticeable pleasant pleasant and noticeable drafty uncomfortable
unnoticeable: less than 50 feet/min.
pleasant: 50-100 ft/min.
pleasant and noticeable:100-200 ft/min.
drafty: 200-300 ft/min.
uncomfortable: over 300 ft/min.
U-factor
high: fast heat transmission
low: low heat transmission
R-value
inverse of U
high: high thermal resistance
low: low thermal resistance
8 areas most to least tolerant of development, according to Ian McHarg’s Design With Nature
surface water marsh floodplain aquifer recharge area aquifer steep slope forests/woodland flat land (except prime agricultural land)
100 YEAR FLOOD
flood that has a 1% chance of occurring in any given year
INFILTRATION BASIN
temporarily collects water and only releases by absorption into the earth; recharges groundwater
CATCH BASIN
temporarily collects water and dumps into storm sewer
BIOSWALE
grassy sloped ditch that filters storm runoff and directs away from impermeable areas. allows water to seep into ground and helps recharge aquifers
CISTERN
tank for collecting and storing water; often a rainwater harvest system for irrigation and non-potable uses
ALBEDO
measure of solar reflectance; 0 is flat black and 1 is mirror
angle of repose for: loose, wet clay or silt compact dry clay wet sand dry sand
loose, wet clay or silt: 30%
compact dry clay: 100%
wet sand: 80%
dry sand:65%
DESIGN FOR HOT ARID CLIMATE
minimize sun exposure and effects of wind
use small windows
optimize thermal mass for big temperature swing
cluster buildings to shade each other
DESIGN FOR HOT HUMID CLIMATE
minimize sun exposure and maximize natural ventilation
use lightweight construction to minimize radiant heat
space buildings far apart to allow breezes
DESIGN FOR TEMPERATE CLIMATE
maximize solar gain in winter and minimize in summer
maximize breezes in summer and minimize in winter
take advantage of daylighting opportunities
DESIGN FOR COLD CLIMATE
orient buildings and openings for maximum protection from cold winds
use small windows and compact shapes to minimize heat loss
use south-facing windows to maximize solar gain
