Coronaproof and future-proof

Since the outbreak of the corona pandemic, it has been high on the political agenda: good ventilation in schools. For Kalsbeek College in Woerden, this was reason enough to have a complete ventilation system installed. The comprehensive school commissioned BLR-Bimon for the engineering and implementation of this.

"The call for good ventilation in schools is not new," says Technical Advisor Gert-Jan de Stigter of BLR-Bimon. "Back in 2015, the Rijksdienst voor Ondernemend Nederland released a Program of Requirements for Frisse Scholen. This is to promote the health, well-being and performance of students in the classroom. Due to corona, these requirements are more topical than ever, since it is known that good ventilation prevents the virus from spreading through aerosols in the air. With this in mind, Kalsbeek College asked us to help think about a ventilation system, both for the main location on Josef Israëlslaan and location Bredius on Burgemeester H.G. van Kempensingel."

Fifty sustainable ventilation units

In the 44 classrooms of the main location and in six classrooms of Bredius, BLR-Bimon installed a ventilation unit with heat recovery and CO2 sensor. De Stigter: "The units ventilate on CO2, but can also be controlled manually. The units suck in clean air from outside and blow it into the rooms at the desired temperature. The dirty air is removed. The energy in this air is reused to heat the supplied air. This provides an efficiency of 75 percent. The units are also equipped with a bypass mode for summer night ventilation."

Letterboxes in the facade

The biggest challenge was in fitting the units into the existing situation. "The spaces above the ceilings were too low," De Stigter explains. "On the second, top floor, we solved this by removing the ceiling tiles. This allowed us to connect to the roof with the system. On the ground and second floor, this was not possible. To be able to draw in enough outside air, we had to make large openings in the facade. In consultation with the structural engineer, we cut 36 openings in the shape of a mailbox. These narrow openings of 90 by 300 millimeters were necessary to keep the rebar in the facades intact. To give the recesses strength, they were fitted with a catch structure made of stainless steel."

Tight schedule

The facade recesses were conceived and worked out during the execution phase of the project. This was due to the tight schedule. The work had to be done during summer vacation. "Of course, we could not drill and saw when the students were in class," De Stigter said. "To meet the schedule, a lot of the work ran in parallel. We also took advantage of spring break. During that week, we installed the units on the second floor. During Christmas break, we came back one more time, to install traffic lights in the classrooms. These traffic lights will indicate the air quality in the classroom."

Maintenance

BLR-Bimon is also responsible for the maintenance of the ventilation system. Replacing the filters is an important part of this. De Stigter: "After one hundred operating hours, we check the filters and set the running time. When the running time is up, we receive a notification that the filters need to be replaced. In this way the ventilation system continues to function optimally and Kalsbeek College is ready for the future. The students are assured of a healthy, fresh and sustainable indoor climate in their classrooms for the coming decades."