When winter comes, the windows close and the air in homes and offices gets heavy: headaches, drowsiness, moisture condensing on the glass, and odors. Particle pollution in outdoor air also rises in the same period. That is why searches for "air purifier" climb every winter. But a device bought without knowing which problem you want to solve often fails to meet expectations.
The difference between the three solutions
| Air purifier | Fresh air unit (heat recovery) | Air conditioner filter | |
|---|---|---|---|
| What does it do? | Circulates and filters indoor air | Filters outdoor air and brings it in, expels indoor air | Coarsely filters the air passing through the indoor unit |
| Dust, pollen, particles | Reduces (with a HEPA filter) | Filters particles in the incoming air | Limited, it is there to protect the unit |
| CO₂ and stuffiness | No effect | The real solution | No effect |
| Odor, humidity, condensation | Partially (carbon filter) | Reduces | No effect |
| Heat loss | None | Low, heat is recovered | None |
| Installation | Plugs into an outlet | Ducted or wall-mounted installation | Comes with the air conditioner |
The measure of stuffiness: CO₂
In a closed room, the carbon dioxide people exhale builds up. You can see it with a simple CO₂ meter: as the values rise, fatigue and loss of concentration increase. An air purifier does not lower this value at all; the only solution is to bring in fresh air from outside. Opening a window works, but in winter it also lets the heat out. A heat recovery fresh air unit largely prevents this loss by transferring the heat of the exhausted warm air to the incoming cold air.
Which one should you choose?
- If you have allergy, pollen, or city dust problems: an air purifier with a HEPA filter, sized for the room.
- Offices, meeting rooms, classrooms, crowded homes: a heat recovery fresh air unit, together with a fine filter if needed.
- Newly built or very well insulated buildings: because the building does not "breathe", mechanical fresh air is almost mandatory.
- Buildings with a central air conditioning or fan coil system: adding a fine filter and adjusting the fresh air damper on the existing air handling unit is often the most economical improvement. Details: HVAC filters.
Do not forget maintenance
The effectiveness of both devices depends on the filter. A clogged HEPA filter reduces airflow; the exchanger of a neglected fresh air unit gets dirty and its efficiency drops. In fresh air units, the filters need to be checked at the start of the season and replaced when necessary. For system design, see our article on how ventilation systems work.
A clean air solution for your space
Tell us the size of the space, the number of people, and your complaint (odor, stuffiness, dust), and we will determine the solution together.
At YOİ Mühendislik, we design, install, and maintain heat recovery ventilation in homes, offices, schools, and healthcare buildings. The number of people, the room volume, and your existing heating and cooling system are enough to determine the need. To pre-calculate the airflow, you can use the airflow and duct sizing tool.
Frequently asked questions
Does an air purifier supply oxygen?
No. It filters the air in the room but does not bring in fresh air from outside; it does not lower carbon dioxide.
Is heat recovery ventilation used in homes?
Yes. Wall-mounted single-room units and ducted central units are also used in residences.
Does an air conditioner's filter clean the air?
The air conditioner filter is designed to protect the unit; it is not a solution for fine particles and CO₂.
Does a fresh air unit cool the house in winter?
Heat recovery models transfer most of the heat of the outgoing air to the incoming air; heat loss is much lower than with opening a window.