The machine room ventilation example uses a multiplier with square footage to determine CFM. What is this multiplier?

The machine room ventilation example uses a multiplier with square footage to determine CFM. What is this multiplier?

• A. 0.01
• B. 0.05
• C. 0.10
• D. 0.50

Answer: (B)

When sizing machine room ventilation this way, you estimate airflow by multiplying the room’s floor area by a standard ventilation rate per square foot. That standard rate is the multiplier, expressed as CFM per square foot. Using 0.05 means you’re giving 0.05 cubic feet per minute of air for every square foot of room. So the formula is CFM = area (ft^2) × 0.05. For example, a 200 ft^2 machine room would need about 10 CFM (200 × 0.05). If you used 0.01, you’d get 2 CFM for the same space; 0.10 would yield 20 CFM; 0.50 would yield 100 CFM—much larger differences that shift the ventilation far from typical modest guidelines. The 0.05 multiplier reflects a common, balanced guideline for this estimation.

When sizing machine room ventilation this way, you estimate airflow by multiplying the room’s floor area by a standard ventilation rate per square foot. That standard rate is the multiplier, expressed as CFM per square foot. Using 0.05 means you’re giving 0.05 cubic feet per minute of air for every square foot of room.

So the formula is CFM = area (ft^2) × 0.05. For example, a 200 ft^2 machine room would need about 10 CFM (200 × 0.05). If you used 0.01, you’d get 2 CFM for the same space; 0.10 would yield 20 CFM; 0.50 would yield 100 CFM—much larger differences that shift the ventilation far from typical modest guidelines. The 0.05 multiplier reflects a common, balanced guideline for this estimation.