®These three solve different problems, and none of them fully replaces the others. Choose the wrong one and you spend money for a fraction of the result.
Opening windows
The cheapest option, and effective at diluting carbon dioxide and clearing odours; but it depends heavily on weather, noise, outdoor smog and the layout of the home. It does not filter outdoor particles, and it does nothing about the formaldehyde source still releasing inside the boards.
Fresh air systems
With the windows closed, they continuously draw in filtered outdoor air and expel stale indoor air — solving "air exchange plus dilution". Suited to smoggy days, street-facing noise, or spaces sealed for long periods; ductwork is best planned before renovation, though wall-mounted and cabinet units work afterwards too.
Air purifiers
Internal circulation filters PM2.5, allergens and some gaseous pollutants, with a clear effect on particles and odours; but they do not address carbon dioxide or oxygen and cannot replace air exchange. Best used as a local boost in an existing room.
How to combine them sensibly
- New or heavily polluted homes first: source treatment plus a fresh air system, to exchange and dilute at the root;
- Everyday boost: purifiers for particles and local odours;
- The basics: when the weather and air quality are good, opening a window is still the best value.