Environmental Conditions & Context: From Regional Climate to Building Response
Climate first, then form
Site conditions set the boundaries for every later design decision, so questions in this domain usually test whether you can move from regional climate to a specific building response.
Macroclimate to microclimate. Latitude, heating and cooling degree days, humidity, and prevailing winds define the regional load. Microclimate then modifies it: topography, vegetation, water bodies, adjacent buildings, and surface materials. Traps appear here - summer and winter prevailing winds often differ, and a south-facing slope is not automatically best in a hot-arid climate where east and west exposure drives the cooling load.
Sun path geometry. Solar altitude is the angle above the horizon; azimuth is the compass bearing. At solar noon on an equinox, altitude = 90° − latitude. Add 23.5° for the June solstice and subtract it for December. Horizontal overhangs control high summer sun on south facades; vertical fins control low east and west sun. Trees help only where deciduous species admit winter sun.
Psychrometrics. On the chart, dry-bulb temperature is the horizontal axis and humidity ratio the vertical. Watch for questions that conflate relative humidity with humidity ratio, or that treat dew point as a fixed value.
Water and soils. Frost depth, water table, expansive clay, and percolation rates drive foundation and drainage strategy.
Worked example: at 40°N, noon sun altitude is 73.5° on June 21 and 26.5° on December 21. A 3-ft overhang casts a shadow of 3 × tan(73.5°) ≈ 10 ft down the wall in June but only 3 × tan(26.5°) ≈ 1.5 ft in December - shading a 10-ft window in summer and admitting sun in winter.