Performance of Modern Passive Stack Ventilation in a Retrofitted Nordic Apartment Building

The paper analyses the performance of a five-storey apartment building equipped with modern passive stack ventilation in Nordic conditions. The passive stack ventilation system was retrofitted in 2019, and novel self-regulating air inlet devices with filters were equipped. The building was simulated with IDA ICE software, where the model of the self-regulating terminal units was developed using manufacturer product data. Several case scenarios were created to analyze the effects of poor maintenance, improved airtightness, and window opening on the system performance. For the analysis, one-room and three-room apartments on the second and fifth floors have been chosen. The CO₂ concentration and indoor air temperature were analyzed and compared with EN 16798-1 standard guidelines. The results show a significant effect of poor maintenance and possibility to open windows on the CO₂ concentration. The results also show a trend for the one-room apartments to overheat despite having a higher air change rate than the three-room apartments. The three-room apartments tolerate over-heating, although they are much more sensitive to poor maintenance. Furthermore, the apartments on the fifth floor are even more sensitive to poor maintenance, and three-room apartments there showed warning levels of CO₂ . Improving the envelope airtightness does not benefit the IAQ of the apartments.