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CFM on a Blower: What's CFM & Why It Matters

Cubic Feet per Minute, often abbreviated, represents the volume of air a blower can move in one minute. It is a crucial measurement indicating the airflow capacity of a blower system. As an example, a blower rated at 100 CFM can displace 100 cubic feet of air every minute. This volumetric flow rate is a primary factor in determining a blower’s suitability for various applications.

Accurate airflow measurement is critical for optimizing system efficiency and performance. Selecting a blower with an appropriate rating ensures effective ventilation, cooling, or material transport. Historically, understanding air movement has been pivotal in industries ranging from mining and agriculture to HVAC and manufacturing, impacting safety, productivity, and energy consumption.

A blower door test quantifies air leakage in a building. By depressurizing or pressurizing the structure and measuring the airflow needed to maintain that pressure difference, the test reveals the equivalent leakage area (ELA) a measure representing the combined size of all gaps and cracks allowing air infiltration or exfiltration. This measurement, expressed in square inches or square centimeters, helps visualize the cumulative size of air leaks, as if they were a single opening. For example, an ELA of 100 square inches suggests the combined air leaks are equivalent to a hole of that size.

Understanding a structure’s airtightness is critical for energy efficiency, comfort, and durability. Excessive air leakage leads to increased heating and cooling costs, drafts, and potential moisture problems. Historically, building airtightness was not rigorously evaluated. However, with the growing emphasis on energy conservation and sustainable building practices, these assessments have become increasingly important. They provide valuable data for determining the effectiveness of air sealing measures and identifying areas requiring improvement. These measurements provide a quantifiable metric for evaluating building performance, enabling informed decisions about renovations and retrofits.