In all buildings where multiple people congregate - such as offices, schools, meeting and event spaces - healthy air quality is even higher on the agenda due to the corona pandemic. Are CO2 meters and air purifiers the solution to acute problems? And what about the long term?
With the relaxation of corona measures, buildings are becoming more crowded again. This increases the risk of transmission of COVID-19 virus and, by extension, other viruses such as influenza. Consequently, many building managers and users are wondering whether they are taking sufficient measures to ensure good air quality.
Uncertainty gives certain entrepreneurs the idea of marketing so-called air purifiers. These promise - through a variety of technologies - to rid polluted air of viruses and bacteria. However, there is still no scientific proof of the effectiveness of these devices, and they are certainly not a panacea. Therefore, a false sense of security is not helpful.
The CO2 meter is the starting point for all measures. When it goes into orange or red, action must be taken. The ministerial decree by Minister Annelies Verlinden - applicable since Oct. 1, 2021 - specifies the mandatory presence of an air quality meter (clearly visible to the public) with real-time measurements in:
The air quality standard for the various sectors is still 900 ppm CO2. When this value is exceeded, the operator must be able, on the basis of a risk analysis, to present an action plan with compensatory measures to go back below this standard. If the value of 1,200 ppm CO2 is exceeded, the operator must also provide an approved system of air disinfection and/or infiltration that ensures an air quality equivalent to the standard of 900 ppm.
The Implication Plan in the Ventilation Task Force Recommendations dated July 12, 2021 previously focused on short- and medium-term measures to ensure adequate ventilation in the context of the COVID-19 pandemic. The Task Force recommends opening windows and/or doors whenever possible to ensure more air movement, preferably permanently (tilted or ajar). However, with winter approaching, this is not the best solution for several reasons: it causes additional heat losses and is also unfavorable acoustically (confidentiality of conversations, disturbing to other employees in the neighborhood).
Asking attendees to leave the room temporarily can also provide temporary relief, as can reducing the room's capacity. The latter option, however, is more drastic, such as in the case where a meeting room without exterior windows and doors is allowed to accommodate only 4 instead of 10 people.
Therefore, the above measures are only a short-term ventilation strategy as a function of virus control. The preferred solutions are those that also work in the long term. In addition, the codex on well-being at work must also be taken into account. This stipulates that every employer must have a risk analysis of indoor air quality. The codex also specifies maximum CO2 concentrations and/or ventilation rates. In general, as in the M.B. mentioned above, the CO2 concentration must not exceed 900 ppm (or 500 ppm above the outside concentration), or a maximum increase over the outside concentration of 500 ppm. For light activities, this corresponds to a ventilation flow rate of 40 m3 per person per hour.
We would like to refer to the recommendations of the Ventilation Task Force under COVID-19 version 2.0. These describe a pragmatic approach to implementing adequate ventilation and air purification to minimize the spread of coronavirus and by extension other viruses indoors. We would be happy to help you translate and apply these recommendations within your building.
A solid and high-performance mechanical ventilation system is always the best solution to guarantee good air quality. We start from a risk analysis to see if the building (still) meets the requirements and standards. Implementing a fixed CO2 monitoring system can be a first step. If structural deficiencies are identified, we can engineer - through modifications to existing installations or from scratch - a ventilation system that meets all comfort requirements, in terms of temperature, relative humidity and air velocities.
Also doubts whether your building is adequately ventilated and meets the guidelines of the Ventilation Task Force and Codex? No idea how to tackle this in practice? Our expert Nico Vandewiele will be happy to explain further via 050 40 45 30 or nico.vandewiele@ingenium.be.
