22 March 2022

Now that the measures have been dropped and we are back on location a lot, you may have concerns about the safety of the ventilation systems in our buildings in The Hague. We would therefore like to bring the following article on this subject to your attention once again:

Recently, we received many questions about the ventilation systems in our locations in The Hague. How safe are the systems? How do they work? To answer your questions, we organised a Q&A on this subject on Friday 3 September. Employees could ask their questions live to Michel Leenders, director Expertisecentrum Vastgoed and ultimately responsible for the ventilation systems, and to Rogier de Bruin, deputy director of the University Facilities Management. Moderator was FGGA's Vice-dean Koen Caminada.

We have listed the most important questions and answers about the systems for you. Do you still have questions? Or do you work somewhere where you think the system is not working properly? Please contact your manager immediately.

About the systems in The Hague

Within the university and certainly in The Hague we have many new buildings, this means that the ventilation is new and therefore also safe. In Stichthage, the building we rent above the central station, the ventilation was also renewed a few years ago and this also meets the safety requirements.

The ventilation in all buildings, except Anna van Bueren (AvB), is controlled by CO2 measurement. The air quality is constantly measured throughout the day using the parts per million (ppm) method. This involves looking at the CO2 value. If the CO2 value exceeds 700 ppm, extra air is blown in to bring the value back down (to clarify: the target value for a well-ventilated room is between 800 and 1000 ppm).

The ventilation in the AVB does not work on the basis of CO2 measurements but has a fixed supply air flow rate.

For all buildings, the ventilation is turned on for an hour every morning so that there is enough fresh air.

Is it wise to open a window where possible or will this disrupt the mechanical ventilation system?

Nothing beats natural ventilation. So if it feels good, definitely do it, but it is not necessary. The mechanical ventilation system is adjusted in such a way that the air is good.

Does good ventilation remove the chance of contamination?

Reducing the virus is all about testing and vaccinating. It is not the case that good ventilation can prevent all infections, but it does help to reduce the chance of infection.

Is there any active monitoring of whether the system is working and actually turned on?

For all ventilation systems, a fault message is triggered if the ventilation system is not working.

Can CO2 measuring devices be placed in the rooms so teachers can see for themselves whether it is time to open a window?

We are not going to do this now, because we would have to do it in all 380 rooms of Leiden University. This is very expensive and it is also not necessary, because we rely on our mechanical ventilation.

How do you deal with small spaces where many people sit together? Like the consulting rooms on the fourth floor of Wijnhaven?

They all have the same mechanical ventilation. So they are also measured during the day and switched on when necessary.

In a number of classrooms in Schouwburgstraat, on the second floor, no windows can be opened. Some teachers sometimes sit there all day with different groups of students and at the end of the day it is very musty. Do these rooms comply with the norm?

The ventilation in Schouwburgstraat is regulated on the basis of CO2 measurements in the hall. Also in the rooms on the second floor where no window can open. If the CO2 value exceeds 700 ppm, extra air is blown in to bring the value back down.

How does the mechanical system deal with larger groups present in a room?

If there are more people in a room than allowed, it can become more difficult. It is therefore important to keep to the maximum occupancy of a room. We do not set up more chairs than the maximum number of students allowed. In addition, we regularly monitor whether there are actually too many students in a room.

What is the situation at LUC's Anna van Buren building? Students also live in the building here. Shouldn't extra ventilation be provided?

This is certainly a special situation. That is why we are going to take extra measurements to be sure that the systems are working properly.

Why do primary schools send a class home when there is an infection and not higher education?

There is no GGD guideline yet. However, this is in the making.

At the moment we advise students infected with corona to report to the study advisor so that we can take measures. This means that non-vaccinated students must undergo a five-day quarantine according to the guidelines, while vaccinated students must keep their distance.

Can teachers ask students to wear a mouth mask in class?

This is the freedom of the teacher to discuss this with the students in class.

Are the buildings of Leiden University in The Hague equipped with Hepa filters?

No. These are filters that may remove part of the virus. If we wanted to do this, we would have to do it in every room, and this is not feasible for us.

In some of the offices at Wijnhaven there is a button you have to press when someone is present. Is this to switch on the ventilation?

No, it used to be. Now this is to ensure that the heating is turned on.