Abstract
Ventilation system design and operation may significantly affect indoor air quality (IAQ). The aims of this case study were to investigate the functionality of a supply air fan-assisted hybrid ventilation system in a newly built school building with reported IAQ problems and to determine the effects of ventilation improvement on measured and perceived IAQ. The ventilation system function was researched simultaneously with IAQ measurements, with an analysis of total volatile organic compounds (TVOC), single volatile organic compounds (VOCs), and indoor mycobiota, and with questionnaires about perceived IAQ. At the baseline, an operational error of the ventilation system was found, which prevented the air from coming into the classrooms, except for short periods of high carbon dioxide (CO2) concentrations. After the ventilation operation was improved, a significant change in indoor mycobiota was found; the dominant, opportunistic human pathogenic species Trichoderma citrinoviride found in settled dust in the classroom before the improvement was no longer detected. In addition, the concentrations of CO2, TVOC, and some single VOCs, especially toluene and decamethylcyclopentasiloxane, decreased. The analysis of the questionnaire results indicated that the perceptions of unpleasant odors and stuffy air decreased, although a statistically significant improvement in perceived IAQ was not observed. The results provided evidence that the properly controlled hybrid ventilation system operating in mechanical supply mode provided adequate ventilation and was effective in decreasing the concentrations of some indoor-generated pollutants. With simple ventilation adjustments, microbiological exposure from building structures might be prevented.
Highlights
In Finland, moisture damage and ventilation disadvantages are the most common problems as they are reported in more than 50% of school buildings [1]
This study focused on one hybrid-ventilated section of the building, which consisted of two equalby equal areas in the first and second floor, was served by one air handling unit and occupied areas in the first and was served by air handling unit and occupied by the approximately approximately
total volatile organic compounds (TVOC) and Volatile organic compounds (VOCs) concentrations were well below the national action values mentioned in the Decree of the Ministry of Social Affairs and Health on at the 100% confidence interval (p = 0.000 in Classroom 1, 387 and 740 measurement points; p = 0.008 in Classroom 2, 387 and 718 measurement points)
Summary
In Finland, moisture damage and ventilation disadvantages are the most common problems as they are reported in more than 50% of school buildings [1]. A recent Finnish study found that 58% of Finnish schools suffer from insufficient ventilation [2]. School environments are often complex and involve several interconnected factors that affect the health of occupants [3,4,5]. Current evidence shows that classroom conditions are significantly associated with the respiratory symptoms of teachers [6]. Res. Public Health 2018, 15, 1414; doi:10.3390/ijerph15071414 www.mdpi.com/journal/ijerph
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