Environmental & Contextual Conditions
Climate first, then context
Environmental analysis starts with the sun and the wind, then layers on the immediate surroundings. You must be able to read a sun path diagram - the difference between altitude (angle above the horizon) and azimuth (compass bearing) - and to reason about solstices versus equinoxes. Know that a sun path diagram is latitude-specific, that the sun rises north of east in summer and south of east in winter in the northern hemisphere, and that low winter sun penetrates deep into a south-facing space while high summer sun does not.
Contextual analysis covers prevailing winds (often different in summer and winter), natural ventilation potential, urban heat island, topography and cold-air pooling, noise and air-quality sources, views and privacy, and the massing and future development rights of adjacent parcels. Vegetation is a design tool: deciduous trees shade in summer and drop leaves for winter gain; evergreens block year-round.
Traps
- Confusing azimuth with altitude, or assuming due south is always the best orientation regardless of climate.
- Mixing up summer and winter prevailing wind directions.
- Forgetting that a shadow study must be run for both solstices and at multiple hours.
Rule of thumb
Shadow length = object height ÷ tan(solar altitude). At 45° the shadow equals the height; at 30° it is about 1.7 times the height; at 60° about 0.58 times. Example: a 40 ft building with a noon winter altitude of 25° (tan ≈ 0.47) casts roughly 85 ft of shadow - enough to shade a plaza across a two-lane street.