ASHRAE 62.1 classroom ventilation, CO2-based demand-controlled ventilation, occupied/unoccupied scheduling, and a gymnasium that legitimately carries two different design ventilation rates.
The project brief: a 118,000-square-foot K-8 school serving 850 students across 42 classrooms, a 9,600-square-foot gymnasium, and a 6,000-square-foot cafeteria — a building where variable, bell-schedule-driven occupancy, not steady-state load, is the central ventilation engineering problem.
This module walks the whole design the way a real mechanical engineer would: the worked ASHRAE 62.1 breathing-zone calculation behind each classroom's 360 cfm design outdoor air rate, how CO2-based demand-controlled ventilation modulates above a fixed area-based floor rather than all the way to zero, the occupied/unoccupied scheduling and setback strategy across the school day and the calendar year, and why the gymnasium needs two entirely different design ventilation rates depending on whether it's hosting a PE class or a spectator event. It also covers the cafeteria's short-duration peak load and the distributed rooftop-unit plant serving all of it. The full worked numbers, complete bill of materials, and finished design reasoning are part of the unlocked module below.