1. Room Size Calculation:

\[ \text{roomSize} = \text{length} \times \text{width} \times \text{height} \]

2. CFM (Cubic Feet per Minute) Calculation:

\[ \text{cfm} = \frac{\text{roomSize}}{5} \]

3. CFM with 25% Duct Resistance:

\[ \text{cfm25} = \text{cfm} + (\text{cfm} \times 0.25) \]

4. CFM with 25% Carbon Filters and Excessively Long Ducting:

\[ \text{cfm25bi} = \text{cfm25} + (\text{cfm25} \times 0.25) \]