Car Ventilation: EN 81-20 1%+1% Top+Bottom, Car Top Fan, Hospital AC, Entrapment CO2 Safe 1 Hour, EN 81-72 Smoke Prevention

Car ventilation is required by EN 81-20 (cl. 8.4.4) which specifies that the car enclosure must have ventilation openings of at least 1% of the car floor area at the top and at least 1% at the bottom to provide natural air circulation by convection. Additional requirements and common implementations: (1) Natural ventilation: the required top and bottom openings allow heat from lighting and passengers to escape upward while cooler air enters from below — the minimum 1% + 1% (top + bottom) rule; (2) Mechanical ventilation fan: in larger or air-conditioned buildings, a fan unit (typically 30–100 m³/h air flow) is mounted on the car top (car top fan) or integrated into the fascia; the fan draws fresh air from the hoistway through the top vents and exhausts warm air through the bottom; (3) In hot climates and in hospitals, full car air conditioning is installed (split unit in the car roof space with condenser in the machine room or on the car top); (4) EN 81-20 requires that the ventilation openings must be protected against accidental contact (finger-safe grilles) and cannot open into the hoistway in a way that creates a shear or trapping hazard with moving parts; (5) Emergency: during a passenger entrapment, some ventilation codes require that the system be able to maintain acceptable CO₂ and temperature levels for the duration of the maximum rescue time (typically 1 hour per EN 81-28); (6) For fire service lifts (EN 81-72), special attention is paid to smoke ingress prevention in the car.

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