Determining the rate at which indoor air is replaced with outdoor air involves quantifying the airflow within a defined space. This process often utilizes measurements of the space’s volume and the airflow rate, typically expressed in cubic feet per minute (CFM) or cubic meters per hour (m/h). For example, in a 1000 cubic foot room with a ventilation system supplying 100 CFM of fresh air, the air exchange rate would be 6 times per hour (100 CFM * 60 minutes/hour / 1000 cubic feet). Various methods exist for this assessment, including tracer gas decay, airflow measurements at inlets and outlets, and building pressure testing.
Understanding ventilation effectiveness is critical for maintaining healthy indoor air quality, controlling airborne contaminants, and optimizing energy efficiency. Historically, natural ventilation played a significant role in building design; however, modern construction often relies on mechanical systems to achieve desired ventilation rates. This shift underscores the increased importance of accurate assessments, which allow for precise control over indoor environments, mitigating risks associated with poor indoor air quality while minimizing unnecessary energy expenditure on excessive ventilation.
