ARE 5.0: PA cheat sheet

Solar geometry: noon sun altitude = 90° − latitude ± 23.5° (plus at summer solstice, minus at winter solstice); azimuth is measured clockwise from true north.

Overhang rule of thumb: depth ≈ window height ÷ tan(noon altitude); size for the summer solstice to shade, then verify the winter solstice sun still penetrates for passive gain.

Prevailing winds are read from a wind rose; windbreaks placed perpendicular to the prevailing winter wind reduce infiltration, while openings oriented to summer breezes support natural ventilation.

Rational method for peak runoff: Q = C·i·A, where Q is peak flow (cfs), C is the runoff coefficient (dimensionless, 0.1–0.95), i is rainfall intensity (in/hr), and A is drainage area (acres).

FEMA flood zones: A and AE map the 1% annual chance flood (AE includes a published base flood elevation); V and VE are coastal high-hazard with wave action; X is moderate or minimal risk.

Sound from a point source drops about 6 dB per doubling of distance; a barrier or berm attenuates only if it breaks the line of sight between source and receiver.

Daylight factor = interior illuminance ÷ exterior illuminance under an unobstructed CIE overcast sky, expressed as a percent; roughly 2% is a common target for ordinary office work.

Heat island mitigation set: high-albedo/high-SRI roofs and paving, shade trees, green roofs, and pervious surfaces, which lower ambient temperature and reduce runoff volume.

Environmental site assessment sequence: Phase I (records review, site reconnaissance, interviews) precedes Phase II (soil and groundwater sampling); both precede brownfield redevelopment.

Zoning math: floor area ratio = gross floor area ÷ lot area; lot coverage = building footprint ÷ lot area; both are zoning limits separate from building-code requirements.

Occupant load = floor area ÷ occupant load factor (e.g., 100 sf/person for business); egress width = occupant load × capacity factor (0.2 in per occupant for stairs, 0.15 in for other components under IBC).

IBC occupancy groups: A assembly, B business, E educational, F factory, H high hazard, I institutional, M mercantile, R residential, S storage, U utility.

IBC Types I–V run from most to least fire resistive; automatic sprinklers commonly allow area increases up to 200% and a one-story height increase, subject to the tables.

Accessible route minimums: 36 in clear width, 60 in turning space, ramp slope max 1:12 with a landing every 30 in of rise, walking surface cross slope max 1:48.

Reach ranges: unobstructed reach 15–48 in above the floor for both forward and side reach; obstructed high forward reach max 40 in.

Guards 42 in minimum at floor openings and open-sided elevated surfaces; handrails 34–38 in above stair nosings.

Zoning relief tools are distinct: variance (hardship), conditional/special use permit (listed use with conditions), and rezoning; Section 106 review applies to federal undertakings affecting historic properties.

Two means of egress are triggered by occupant load thresholds, common path limits, and travel distance limits that vary by occupancy and construction type.

Slope = rise ÷ run, expressed as a percent; 5% is a comfortable walkable grade, and accessible routes cap running slope at 1:20 and cross slope at 1:48.

Contours: spacing is inversely proportional to slope (close = steep); a contour crossing a drainage swale forms a V pointing upstream.

Balanced cut and fill minimizes haul cost, but bank volume, loose volume, and compacted fill volume differ by swell and shrinkage factors.

Site inventory layers: boundary survey, topography, soils/geotech, vegetation, hydrology and floodplain, utilities, easements, views, noise sources, and solar access.

Net program area divided by the target efficiency yields required gross area; typical efficiency is 65–80% depending on building type and core size.

Parking planning figure: roughly 300–350 sf per space including drive aisle; verify against local ratios and count accessible spaces from the code table.

Stormwater rules commonly require post-development peak discharge and volume to match pre-development conditions, achieved with detention, infiltration, and pervious paving.

Utility feasibility: confirm invert elevations and capacity; a 4 in gravity sanitary line needs at least about 1/8 in per foot of fall (roughly 1%).

Wetlands, floodplains, and stream buffers constrain the buildable area; buffers of 25–100 ft are common and trigger federal or state permitting.

Programming sequence: space list with net areas and occupancies → adjacency matrix → bubble diagram → block plan → schematic plan, adding dimensional constraint at each step.

Core components (elevators, egress stairs, restrooms, shafts) typically consume 15–25% of the floor plate; office net-to-gross efficiency is often 75–85%.

Structural bay sets the parking module: a double-loaded parking bay needs roughly 60 ft of column-free span to fit two rows of stalls plus a drive aisle.

Daylight and natural ventilation generally work with lease spans of 40–45 ft or less from core or corridor to exterior wall; deeper plates require mechanical or atrium strategies.

Floor-to-floor height = clear ceiling + structure + mechanical/electrical zone; verify against existing floor-to-floor dimensions in adaptive reuse.

A change of occupancy classification in an existing building triggers code evaluation of egress, fire resistance, sprinklers, and accessibility under the applicable existing-building code.

Elevator planning rule of thumb: about one elevator per 40,000–50,000 sf of office area, confirmed by a traffic analysis for the actual population.

Space planning check: assignable area plus walls, circulation, core, and mechanical must reconcile to the gross area used for cost and code calculations.

Envelope performance depends on continuity of insulation; thermal bridging at slab edges, balconies, and shelf angles degrades the assembly's effective R-value.