Impacts of energy retrofits on indoor CO2 concentration and air change rate: 10th international Conference IAQVEC 2019: Indoor Air Qualy, Ventilation and Energy Conservation in Buildings. 5-7 September 2019, Bari, Italy

Impacts of energy retrofits on IAQ were studied in two European countries, Finland and Lithuania. Air change rates were estimated based on air flows measured through ventilation outlets and 24-hour monitoring of CO2 concentrations before and after various energy retrofits in multi-family buildings. The air change rates (ACR) after retrofits were higher in apartments with mechanical ventilation in Finland. The ACR after retrofits were smaller in all study groups in Lithuania, yet noticeably smaller in apartments with mixed ventilation. CO2 concentrations in all study groups in Finland were lower than in Lithuania. Also, some decrease in CO2 concentrations was noticed after retrofits in Finland, whereas an opposite trend was observed in Lithuania. In conclusion, impacts of energy retrofits were mainly marginally positive in Finland and mainly negative in Lithuania. Positive impacts were typically noticed in apartments with mechanical ventilation and "good" IAQ before retrofits. On contrary, negative impacts were noticed in apartments with natural ventilation and "adequate" IAQ. It was concluded that IAQ should be assessed before and after retrofits.