Project Planning & Design: Concept, Life Safety, and Accessibility
Schematic design
Schematic design translates the program into concept: massing, orientation, organization, and systems strategy. Passive strategies - orientation, daylighting, envelope, natural ventilation - come first because they are cheapest to implement at this stage. Structural, mechanical, and envelope decisions made now constrain every later phase.
Life safety and egress
The egress system has three parts: exit access, the exit, and exit discharge. Check occupant load (area ÷ occupant load factor), number of exits, egress width, travel distance, common path of travel, dead-end corridors, and separation between exits. Egress width = occupant load × the code width factor, subject to minimums.
Accessibility
Accessible routes must connect site arrival points, entrances, and all public and common-use spaces. Key numbers: 32-inch clear door width, 1:12 maximum ramp slope with 60-inch landings and a 30-inch rise per run, 60-inch turning spaces, and defined reach ranges.
Traps
Occupant load factors apply to gross or net area depending on occupancy. Travel distance is measured along the actual path, not in a straight line. The common path limit is shorter than the total travel distance limit. Exit separation is measured in a straight line, not along the corridor.
Worked example
A 12,000 sf sprinklered business occupancy: 12,000 ÷ 150 = 80 occupants. Required egress width = 80 × 0.15 in = 12 in, so door width alone is not the constraint - but because the calculated load exceeds 49, two remote exits are required.