Improvement of indoor climate and ventilation system in a renovated multistoried residential building.

The goal of this project was to improve the quality of indoor air in a multistoried residentialbuilding of 81 flats built in 1960. The building is located in a heavily built urban area ofHelsinki. The building had a mechanical exhaust ventilation system without outdoor air inlets.A questionnaire was sent to occupants and a condition survey was made prior to renovation. Themain indoor climate problem was draught with a prevalence of 60 %. Other almost as commonproblems were traffic noise also during nights and dust coming from the street. The ventilationsystem was fully unbalanced with reduced exhaust air flows partly due to uncleaned exhaust airvents. A new type of fresh air window with air filtration (EU 5) and good acoustic performancewas developed. The sound insulation value measured in field was 42 dB(A). When these newwindows were installed in the dwellings a new questionnaire was sent to occupants. The resultsshowed clear improvement in all indoor climate related factors. The habitants were much moresatisfied with the performance of ventilation system after the renovation measures.