Ventilation Requirements Calculator

Primary Service Type sets the base required ACH from a four-entry table (lines 28-34). Stations above two add 0.5 ACH each through extraStations (lines 37-38), and the sum is capped at thirty. With acrylic as the default service, four stations yield twenty-one ACH; eleven stations push twenty-four and a half; twenty-seven stations hit the thirty ACH ceiling.

Adjusted ACH depends only on service type and station count (lines 28-38). Room dimensions enter later when converting ACH to General Exhaust CFM by multiplying room volume — length times width times height (line 23) — by adjusted ACH and dividing by sixty (line 41). A larger room therefore needs more CFM and possibly more fans, but the target air-change rate itself stays the same for identical services and stations.

When Existing Ventilation equals source capture at tables, Effective Total CFM becomes sixty percent of general exhaust CFM plus seventy-five CFM times each active station (lines 50-52). Basic HVAC and no ventilation paths pass general exhaust through unchanged (lines 53-57). Make-up Air CFM always matches the effective exhaust total (line 63) so intake balances what is pulled out.

Compliance Score is a fixed heuristic, not a ppm calculation. Source capture with adjusted ACH meeting the service target scores ninety-five (lines 70-71); basic HVAC near the target scores seventy (lines 72-73); no ventilation scores fifteen for acrylic or thirty-five for lighter services (lines 74-75). It reflects whether the modeled ventilation tier plausibly supports OSHA PEL guidance — professional air monitoring is still required for a definitive assessment.