Effects of Ventilation Improvement on Measured and Perceived Indoor Air Quality in a School Building with a Hybrid Ventilation System

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.

Indoor Air Pollution, Related Human Diseases, and Recent Trends in the Control and Improvement of Indoor Air Quality

“…Thus, hybrid ventilation systems are designed to take advantage of both mechanical and natural ventilation systems, in order to decrease energy consumption and increase the use of sustainable technologies [21]. In hybrid ventilation systems, the shortcomings of natural ventilation will be compensated by mechanical components [22]. In summary, in heating, ventilation, and air conditioning (HVAC) systems of buildings, ventilation plays a key role in creating suitable IAQ, but it is also responsible for energy consumption.…”

Variability of Total Volatile Organic Compounds (TVOC) in the Indoor Air of Retail Stores

“…ASHRAE has established Standard 62.1 that requires minimum ventilation rates in commercial buildings to preserve “occupants’ health, safety and well-being” [29]; however, a critical review found that half of the stores failed to meet relevant ventilation standards [14]. Also, previous studies reported inconsistency in IAQ improvement by increased ventilation: some were effective [40], and some were not [14,41]. Concentrations of fine particulate matter, formaldehyde, and acetaldehyde in stores often exceeded the guidelines, despite stores’ compliance with ASHRAE Standard 62.1 [14].…”

Influence of the Airflow in a Solar Passive Building on the Indoor Air Quality and Thermal Comfort Levels

“…This section presents the evaluation of the PMV index in 13 compartments (numbered as 16, 19,35,37,42,46,52,58,81,90,106, 111 and 129) distributed over the 3 floors and selected because their thermal responses were representative of most of the other building compartments.…”

“…Indoor pollution sources that release gases or particles into the air are the primary cause of indoor air quality problems in buildings [41]. Inadequate ventilation can increase indoor pollutant levels if it cannot provide fresh outside air to dilute emissions from indoor sources and cannot remove indoor air pollutants to outside the building [42,43]. High temperature and humidity levels also can increase concentrations of some pollutants [44].…”