Worldwide, there is an increasing number of publications related to air cleaning and there is also an increasing sale of gas phase air cleaning products. This puts a demand for verifying the influence of using air cleaning on indoor air quality, comfort, well-being and health. It is thus important to learn whether air cleaning can supplement ventilation with respect to improving air quality i.e. whether it can partly substitute the ventilation rates required by standards. This is one of the objective of IEA-EBC Annex 78 'Supplementing Ventilation with Gas-phase Air Cleaning, Implementation and Energy Implications'. Annex 78 also looked at gas phase air cleaning technologies, energy impact of using air cleaners to improve indoor air quality and long term performance of gas phase air cleaners.

International Standards for Ventilation (Indoor Air Quality) like EN16798-1, ISO17772-1 and ASHRAE 62.1 are mainly based on criteria for the Perceived Air Quality (PAQ) combined with a check for individual substances. There is however no testing standard for air cleaners that is based on perceived air quality.

The present report describes a test method for gas phase air cleaners based on PAQ.

The proposed method comprises two phases of testing of air cleaners. The first phase examines whether the air cleaner can improve or reduce air quality (qualitative testing). In contrast, second phase thoroughly examines the air cleaner performance (quantitative testing). The idea behind the proposal is the efficient use of resources: that air cleaners that do not pass Phase 1 should not be tested in Phase 2.

No firm recommendations can be made on whether the sensory evaluations of air quality when testing the performance of air cleaners should be made on the air extracted from the experimental rooms (facial exposures) or upon entering the rooms (whole-body exposures).

The overall results of sensory evaluations for individual conditions were not always consistent. For that reason, at this moment, it can be recommended to use both sensory evaluations of odor intensity and acceptability of air quality when testing the performance of air cleaners using sensory methods. They both provide a more complex characterisation of sensory effects.

The relationship between ventilation rates and sensory ratings of acceptability of air quality and odour intensity was non-linear. Consequently, when determining the clean air delivery rate for air cleaners and comparing against the effects obtained by ventilation, it is necessary to perform the tests at different ventilation rates. Examining CADR only at one ventilation rate is insufficient and these results should not be extrapolated to other ventilation rates.

The ISO 16000-44 standard was approved in 2023. It describes a test method for measuring perceived indoor air quality for testing the performance of gas phase air cleaners. The method in the standard is similar to the one examined in the present experiments. The perceived air quality is determined using the acceptability of the air quality and odour intensity. The air assessed by a panel is presented via a sniffing device (facial exposure). If measurement accuracy can be guaranteed, the panel can also enter a chamber directly to assess the air (whole-body exposure). The air change rate of the test chamber is set at 0.50/h (±0.03/h) and 2.0/h (±0.12/h) in ISO, which is the same as in the present study at 7.5 L/s and 30 L/s. The experimental methods used in this study are generally comparable with those proposed by the standard. Therefore, the methodology described and examined in the present paper supports and validates, to some extent, the approach proposed by ISO 16000-44.