[Joakal]

I heard that you would need about 40(?) plants per person. Best advice was to be well ventilated unless the outdoor CO2 is worse than indoors.

[antisthenes]

You literally can't have enough plants in the house to compensate for the CO2 production of its inhabitants.

You would have to place water immersed algae farms on every open space in the house and keep them illuminated with artificial light 24/7, because plants will produce CO2 at night otherwise.

Like you said, good ventilation is far more effective than any plant.