Kid in classroom with mask

Air Cleaners vs Fresh Air Ventilation

COVID19 has placed the spotlight on the importance of Indoor Air Quality (IAQ), resulting in pressure on institutions, such as schools, offices, and elderly care facilities, to improve their IAQ. Air purification devices have become a popular option. Yet, stakeholders need to be aware that some products fall short of providing optimum occupant health and comfort compared with fresh air ventilation systems. Here’s why…

There is more than one way to achieve good Indoor Air Quality (IAQ). Air cleaners, or mobile air purifiers, have emerged as an option among people looking to improve IAQ. While such products serve a particular purpose, they should not be considered an alternative to fresh air ventilation.

Air cleaners cannot provide optimum IAQ and must only be seen as a stopgap or temporary solution, especially with denser buildings. Ventilation for good IAQ is critical to our health and job performance, and we must not lose sight of the big picture in the name of low-cost options, which could be detrimental to IAQ.

Air CleanersFresh Air Ventilation
FunctionAir purification devices and air cleaners are essentially consumer products.Fresh air ventilation systems are engineered solutions that usually require expertise and the assistance of an installer to be integrated into spaces.
ScopeAir cleaners do not substantially impact larger spaces that require larger fresh air volumes, as it is only cleaning a small area.Ventilation solutions can introduce fresh air to achieve a proper, clean, and safe environment for all types of spaces. Modern ventilation systems feature ducts, sensors, and VAV systems to better control airflow and air distributions than a remote device.
Airflow flexibilityAir cleaners can alter air quality only in one direction.Ventilation systems can be bi-directional. They require calculations that ensure sufficient airflow, air volume and air changes to address the requirements of occupants in the room.
Removal of dangerous contaminantsAir purifiers can only partly remove dangerous contaminants. If equipped with coal filtration, it might remove odours, but, in both cases, they are not sufficient to create a healthy and comfortable indoor environment.Ventilation systems can supply fresh air for respiration, as well as remove emissions from materials and people or “used air”.
Replacement of CO2Air cleaners cannot replace stale air within the room, bring in O2 or reduce the CO2 level. While some cleaning properties vary significantly within the solutions in the market, these devices recirculate air and filter it to varying extents.Ventilation systems do not need to clean the indoor air because they transport the polluted air outside and bring fresh air inside.
Ozone usageSeveral air cleaners use ozone. Even in minimal concentrations, ozone is hazardous to health. Symptoms include irritation of the mucous membranes and respiratory tracts. Asthmatics are also affected with a higher risk of impaired lung function. Health authorities advise against staying in a room when ozone is used unless the space is properly ventilated beforehand.Fresh air ventilation systems are more efficient and healthier because occupants are not at risk of encountering harmful ozone substances through the system.
Radon controlNo air purifier can reduce the radon content in a room. At most, some models can measure the radon content in a specific area of a room.The only way to reduce radon in a room is to use a fresh air ventilation system.
Humidity and temperature controlAir cleaners cannot usually regulate humidity, which is essential to safeguard the indoor environment for occupants and the building itself.Quality ventilation systems can control humidity, and temperature, operating as a comprehensive and targeted treatment of the supply air to maintain the best possible indoor air quality.
Risk of mouldThe air cleaner can never reduce the humidity in the room and the humidity is the breeding ground for mould.Fresh air ventilation can easily remove humidity in the building and stop mould growth that is caused by high air humidity.
Third-party certificationIt isn’t easy to judge the validity of the claims presented by manufacturers of air purification devices and air cleaners. Apart from the recently introduced, but not yet very widely utilised, air cleaner certification programme by Eurovent Certification, there are no legitimate, international third-party certifications that can guarantee manufacturer claims that consumers can rely on.Ventilation solutions in the market are available, certified by the world’s most recognised independent, thirdparty certification bodies, such as Eurovent Certification and HVI. These performance certification schemes are valuable tools as they help empower customers with the correct data by validating information declared by manufacturers.
Regulatory complianceAir cleaners do not fall under the Ecodesign for Energy-Related Products.Fresh air ventilation systems fall under Ecodesign regulations from the Euroepan Union.
Use of HEPA filtersMany air purifiers have HEPA filters in use. However, these high-quality filters generate a relatively high-pressure loss, which increases with each operation hour due to the increasing contamination. This leads to high energy consumption for a unit that only does part of the job of ensuring good IAQ.For general ventilation applications, HEPA filters are commonly not used, recommended or necessary. Instead, one or more filtration stages including bag or panel filters are applied, which have a much lower pressure drop than HEPA filters.
Filter maintenanceFilters in air cleaners must be changed relatively frequently. It carries high maintenance costs, but there is also a risk of dirty filters not being appropriately handled and substances that have already been filtered returning to the environment again in high concentrations.Ventilation solutions’ filter changes should only be carried out by qualified personnel with hygiene training. These are also outlined in recommendations as part of solutions’ certifications. VDI 6022, for example, advises that filters should only be changed with a protective mask due to the extremely high dust exposure.
Sound levelsAir cleaners that continue operating even with dirty filters require greater performance from the fans, which inevitably leads to a higher noise level. Although there are cleaners designed with low noise levels, their effectivity is limited.Quality ventilation systems have silencers to reduce the sound from the unit, and the duct system also minimises noise during operation. Furthermore, ventilation solutions’ components are designed with low sound to ensure it does not reach disturbing levels.

Air purification devices, even those with HEPA filters, UV lights and humidification features, have a specific function. There is a time and a place for such systems, and there are certain occasions where it can be helpful. Air cleaners add on to secure the indoor air quality. However, they cannot replace ventilation but only support it selectively or serve as an emergency solution where ventilation is unavailable.

Other cases where air cleaners would be helpful include:

  • Cases where in existing buildings do not have a duct system in existing buildings

  • Situations when there is an immediate need to filter foul odours in a building

  • Filter out viruses such as COVID19


Even though air cleaners should be considered interim solutions, they must meet minimum requirements. The devices must ensure minimum airflow volumes and thus be of a certain size. Quality High-Efficiency Particulate Air (HEPA) filters, for example, those tested and certified by third parties for filter integrity, should be a standard feature of air purification devices and air cleaners. It is also important to note the effectiveness of the HEPA filters is also subject to many factors, such as the tightness around the casing of the HEPA filter or the growth of viruses on the dirty side of the HEPA filter.