In the village of Jirnsum in The Netherlands, there is a school building that is built according to the Passive House concept. Using a single smart ventilation system, demand-controlled ventilation with cooling or heating is applied. The classroom ventilation is controlled by the BaOpt control system. Air handling units from Systemair function very well here. The school chose three Topvex units that are larger in size. Because of this, the air handling units have overcapacity, which means the fans can run slower. This makes the air handling units function virtually silently. It also means there is an energy saving of about 25%.