Assessing the Impact of Natural Ventilation on Indoor Air Quality in Residential Buildings

Thesis Abstract

The increasing awareness of indoor environmental quality and its direct impact on occupant health and comfort necessitates a comprehensive understanding of natural ventilation's role in residential settings. Despite widespread recognition of natural ventilation as a sustainable strategy to improve indoor comfort, there exists a knowledge gap regarding its specific influence on indoor air quality (IAQ) parameters within diverse residential contexts. This study aims to quantitatively and qualitatively assess the impact of natural ventilation on IAQ in residential buildings, with specific objectives to determine the relationship between ventilation rates and indoor pollutant concentrations, evaluate occupants' perceptions of air quality in naturally ventilated homes, and identify architectural and behavioral factors influencing ventilation effectiveness. The research adopts a mixed-methods approach, integrating empirical field measurements with participant surveys. The field component employs a cross-sectional design, targeting a representative sample of 150 residential units in urban areas, selected via stratified random sampling based on building typology and age. Data collection involves continuous monitoring of indoor air pollutants (including particulate matter (PM2.5 and PM10), carbon dioxide (CO2), volatile organic compounds (VOCs), and humidity levels) over a one-week period, utilizing calibrated portable air quality analyzers. Concurrently, structural parameters such as window and door configurations, orientation, and opening patterns are documented through direct observation and occupant diaries. The qualitative component involves semi-structured interviews with 50 residents to capture perceptions, behavioral habits, and awareness related to natural ventilation and IAQ. The validity and reliability of measurement instruments are ensured through calibration and pilot testing, and data analysis employs multiple regression analysis to examine the relationship between ventilation parameters and pollutant levels, while thematic analysis is applied to interview transcripts to extract prevailing perceptions and behavioral influences. Expected findings are projected to reveal significant inverse correlations between effective natural ventilation rates and indoor concentrations of particulate matter, CO2, and VOCs, with architectural features such as window size and orientation, and occupant behaviors like window opening frequency, significantly moderating IAQ outcomes. The study anticipates that residents' perceptions of air quality are generally aligned with measured pollutant levels, although some misconceptions about ventilation effectiveness may persist. The integration of quantitative and qualitative data aims to develop a comprehensive understanding of the complex interactions influencing IAQ in naturally ventilated residences. This research contributes to the existing body of knowledge by providing empirically grounded insights into how natural ventilation strategies influence IAQ in residential environments under real-world conditions. Furthermore, it informs guidelines for architectural design, occupant behavior, and policy development aimed at optimizing natural ventilation for healthier indoor environments. The study concludes that tailored interventions, including enhanced architectural features and occupant education on ventilation practices, can significantly improve IAQ and occupant health. Recommendations include adopting design standards that maximize effective cross-ventilation, promoting awareness campaigns to encourage optimal window utilization, and integrating natural ventilation considerations into building codes. Future research avenues are suggested to explore longitudinal impacts and the integration of smart ventilation controls in residential settings for sustained indoor air quality improvement.