1. Differences in core working principles

Circulation mode

Fresh air system: realizes indoor and outdoor air exchange (external circulation) through pipes or independent equipment, actively introduces filtered outdoor fresh air and discharges indoor dirty air

Air purifier: only circulates and filters the existing air in the room (internal circulation), and cannot replenish oxygen or discharge carbon dioxide

Purification logic

Fresh air system: reduces the concentration of pollutants through the dilution principle, for example, formaldehyde is discharged through continuous ventilation

Air purifier: relies on the filter to adsorb or decompose pollutants, requires regular replacement of filter elements, and has limited effect on gaseous pollutants such as formaldehyde

2. Function and effect comparison

Air replacement capacity:

Fresh air system: can replenish oxygen, reduce carbon dioxide concentration, and solve the problem of stuffiness and lack of oxygen

Air purifier: cannot improve oxygen content, and long-term closed use may cause carbon dioxide to exceed the standard

Pollution treatment Treatment scope:

Fresh air system: Filter PM2.5, dilute formaldehyde/VOC and other decoration pollution, suitable for long-term environmental governance

Air purifier: Efficiently remove PM2.5, pollen, dust mites and other particles, strong short-term purification ability

Temperature and humidity adjustment:

Fresh air system: Some models have heat exchange function to reduce energy loss during ventilation

Air purifier: No temperature and humidity adjustment function, only purifies air

III. Applicable scene suggestions

Situations where fresh air system is preferred

Newly renovated houses need to remove formaldehyde/VOC for a long time

Enclosed spaces with many people (such as offices and living rooms) need to stably control the concentration of carbon dioxide

When the outdoor air quality is good, continuous ventilation is required

Situations where air purifier is preferred

Short-term response to haze, pollen season or pet hair loss

Renovated houses cannot be renovated and installed with fresh air

Quick purification of particles in small rooms