Ventilation rates are determined by calculating the airflow rate and dividing it by the volume of the space. Airflow is typically measured in cubic feet per minute (CFM), while room volume is calculated by multiplying length, width, and height. For example, a 10ft x 10ft x 8ft room has a volume of 800 cubic feet. If a ventilation system supplies 800 CFM to this room, the ventilation rate is 1 air change per hour (ACH). This signifies that the equivalent of the entire room’s air volume is replaced every hour.
Understanding and controlling ventilation rates is crucial for maintaining healthy indoor air quality. Proper ventilation dilutes and removes indoor pollutants, such as volatile organic compounds (VOCs) and carbon dioxide, which can negatively impact occupant health and productivity. Historically, natural ventilation through windows and cracks played a significant role. However, modern building design often prioritizes airtight construction for energy efficiency, making mechanical ventilation systems essential for achieving adequate airflow and acceptable indoor environmental quality.
