ARE 5.0: PPD cheat sheet

Solar altitude at solar noon = 90° − |latitude − solar declination|; declination is positive in Northern Hemisphere summer and negative in winter.

In the Northern Hemisphere the sun rises generally east, is due south at solar noon, and sets generally west; noon altitude peaks at the summer solstice and bottoms at the winter solstice.

Long-axis east-west orientation reduces east- and west-facing glazing, the largest source of low-angle solar gain and glare; south glazing can be shaded with overhangs.

Shadow length behind a vertical shade = height / tan(solar altitude); an overhang shades a window when its projection exceeds this length.

Prevailing winter winds raise infiltration and conductive loss; windbreaks reduce speed, while summer breezes support natural ventilation and should not be blocked.

Heat islands form where low-albedo pavement and roofs, sparse vegetation, and waste heat raise local air temperature; high-albedo surfaces, trees, and water reduce the effect.

Impervious site area increases peak runoff and pollutant loads; detention, retention, bioswales, and permeable paving reduce peak flow and improve quality.

Daylight factor = interior horizontal illuminance / unobstructed exterior horizontal illuminance × 100; it excludes direct sun and varies with sky conditions.

Noise control follows source-path-receiver: distance, barriers, mass, decoupling, and absorption; background noise can mask but does not reduce source level.

Occupancy classification groups spaces by use and hazard; mixed uses may be separated by rated construction or treated as nonseparated with area limits.

Two exits are generally required when occupant load, common path, dead-end, or travel distance exceeds code thresholds; the exact limits vary by occupancy and sprinklers.

IBC egress capacity is commonly 0.2 in (5.1 mm) per occupant for level components and 0.3 in (7.6 mm) per occupant for stairs; verify edition and occupancy.

Exit access travel distance is measured along the actual path from the most remote point to an exit; limits depend on occupancy, sprinkler status, and construction type.

Type of construction (I–V) sets required fire resistance of structural elements; occupancy and area/height thresholds determine the minimum type.

Accessible route: 36 in (915 mm) minimum clear width, 60 in (1525 mm) turning space, 32 in (815 mm) door clear width, and 1:12 maximum ramp slope with 30 in (760 mm) rise per run.

Floor area ratio = gross floor area / lot area; zoning also controls lot coverage, setbacks, height, and use.

Allowable building area and height increase with frontage and sprinkler protection and decrease with higher occupancy hazard; check both tabular and formula methods.

Plumbing fixture counts derive from occupant load, use, and fixture ratios; accessible fixtures require clear floor space and reach ranges.

Total HVAC load = transmission + solar + internal + infiltration + ventilation; sensible load changes dry-bulb temperature, latent load changes moisture.

Human comfort is roughly 68–75°F (20–24°C) and 30–60% RH; cooling coils dehumidify when coil temperature is below the air dew point.

Economizer operation uses cool outdoor air instead of mechanical cooling when outdoor air enthalpy or temperature is lower than return air.

VAV systems vary supply air volume while holding supply temperature; CAV systems hold volume and vary temperature.

Drainage slope: 1/4 in per ft (2%) for pipes 2½ in and smaller; 1/8 in per ft (1%) for 3 in and larger, unless code allows otherwise.

Electrical power = volts × amperes; for single-phase loads, watts = V × A × power factor; panel and feeder sizing include demand factors and voltage drop.

Passive fire protection uses rated assemblies and compartmentation; active protection uses sprinklers, alarms, smoke control, and standpipes.

Elevator handling capacity depends on car size, speed, population per floor, and round-trip time; queuing and waiting time drive car count.

Structural load path: gravity loads travel from slabs to beams to columns to foundations; lateral loads resist through braced frames, shear walls, or moment frames.

Assembly U-factor = 1 / total R; total R sums layer resistances plus interior and exterior film resistances, but framing bridges reduce effective R.

Thermal bridging occurs where high-conductivity framing, shelves, or corners bypass insulation; continuous insulation and thermal breaks reduce it.

In cold climates, vapor retarders belong on the warm interior side; in warm-humid climates, avoid interior vapor barriers that trap moisture.

Air barriers control infiltration and exfiltration; they must be continuous across joints, penetrations, and intersections with roofs and foundations.

STC rates airborne sound isolation; IIC rates impact sound isolation; mass, decoupling, absorption, and sealing improve performance.

Gypsum board fire ratings depend on assembly thickness, stud type, fastener spacing, and joint treatment; penetrations require listed firestop systems.

Concrete strength depends on water-cement ratio, curing, and aggregate; lower w/c generally increases strength and reduces permeability.

Modular coordination sizes components to common modules, reducing cutting, waste, and clashes; brick and CMU modules differ from wood/steel panel modules.

Flame spread and smoke-developed ratings describe surface burning; they are separate from fire-resistance ratings of assemblies.

Net assignable area excludes circulation, walls, shafts, and mechanical space; gross area includes them, so net-to-gross efficiency = net / gross.

Adjacency matrix scores required proximity and separation among spaces; it informs bubble diagrams and block planning.

Space requirement = occupant count × area per occupant + equipment footprint + clearances and circulation.

Public, private, and service zones are typically separated by circulation; noisy or odorous spaces belong away from quiet or clean spaces.

Modular planning aligns structure, ceilings, and partitions to a common module to reduce waste and coordinate MEP.

BIM clash detection finds geometric conflicts among structure, ducts, pipes, and conduit before construction; it does not replace field coordination.

Universal design integrates accessibility and usability for varied users from the start; later retrofits usually cost more and constrain layout.

Commissioning verifies that systems meet design intent; early integration of controls and sequences reduces operational problems.

Project budget = construction cost + soft costs + contingency + land and financing; gross square footage is the usual denominator for cost per square foot.

Estimate accuracy improves from order-of-magnitude to schematic to design development to construction documents; contingency shrinks as design progresses.

Design contingency covers unknown scope during design; construction contingency covers changes during construction; owner contingency covers owner-directed changes.

Life-cycle cost = initial cost + present value of operating, maintenance, and replacement costs − salvage value.

Simple payback = incremental first cost / annual savings; shorter payback means faster recovery but ignores time value and later costs.

Value engineering analyzes function and cost; it should preserve required performance rather than merely cut scope.

Cost escalation adjusts historical or current costs for time and location using indices; location factors adjust for regional labor and material prices.

Fast-tracking overlaps design and construction to shorten schedule but increases coordination risk and change orders.