Healthy Living in the Swollenaer
How demand-driven collective heat recovery ventilation in 87 sustainable rental apartments in Zwolle saves space, simplifies maintenance, and contributes to a higher BENG score.
There is high demand for affordable, sustainable rental housing in Zwolle. The SWZ Group seized the opportunity to transform a vacant office building (De Swollenaer) into 87 social rental apartments. Contractor Plegt-Vos used prefabricated facades and bathrooms from its own “Slimme Huisfabriek” to ensure a fast and cost-efficient completion. For the installer, Keizers Installatietechnieken, the question then arose: Which ventilation system is best suited for this type of project?
Zehnder recommended a centralized, demand-controlled ventilation system with heat recovery for the entire building. At the heart of the solution is a single central ComfoAir Q600 unit in the shared mechanical room, which handles the supply and exhaust air for all 87 units. In each apartment, two ultra-compact ComfoVar Aero damper modules and one Control Unit control the ventilation fully automatically. They do this based on the CO₂ levels measured in the living room and the master bedroom.
In public housing apartments, every square meter is precious. A traditional heat recovery unit per unit typically takes up 0.3 to 0.5 m², space that residents would prefer to use for other purposes. The goal was to maximize living space for residents without compromising air quality.
The ComfoVar Aero valve modules can be installed flexibly and independently of one another on the ceiling or wall and take up very little living space. There is no need for a large heat recovery unit in a utility closet or storage closet. Two modules (one for supply, one for exhaust) and the corresponding Control Unit are sufficient for each apartment. This saves dozens of centimeters of closet space that residents can now use for other purposes.
The teardrop-shaped air diffusers also ensure draft-free distribution of fresh air, even at low flow rates. No complaints about cold air currents directed at residents.
With 87 apartments and a diverse mix of residents (including seniors, people receiving housing support, and asylum seekers), scheduling individual service visits is complex, time-consuming, and potentially disruptive. SWZ wanted a system in which filter replacement and technical maintenance could be performed collectively and outside the apartments.
The ComfoAir Q600 is located in the building’s communal mechanical room. Filter replacement, inspections, and technical service are performed collectively, outside the apartments. For SWZ, this means fewer scheduled appointments with residents, less logistical hassle, and significantly lower management costs over the building’s entire lifespan.
The ComfoVar Aero’s damper modules are maintenance-free; random spot checks are sufficient. They can be monitored and adjusted from a single central location via the Control Units, without entering the residence.
De Swollenaer had to comply with the current BENG requirements. The ventilation system had to be demonstrably demand-driven, with a recognized link between CO₂ measurement and ventilation flow rate as the basis for the energy performance calculation.
The CO₂ sensors in the living room and master bedroom continuously measure indoor air quality. The ComfoVar Aero automatically adjusts the airflow per apartment to actual demand. Is the home empty? Then the air diffusers automatically open to let in more fresh air.
This demand-driven principle is the recognized basis for the BENG energy performance calculation. By demonstrably reducing ventilation when it is not necessary, the energy performance of the entire building improves and energy costs for residents decrease.
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