Hvac Design Calculations Excel ((exclusive)) May 2026

Store a friction loss vs. CFM vs. diameter table. Use INDEX/MATCH or linear interpolation to find the nearest duct diameter for a given CFM at your target friction rate.

Below is a breakdown of the core HVAC calculations you can perform effectively in Excel, along with the logic to build them. Excel excels at handling the repetitive yet formulaic nature of heat gain calculations. The most common manual method is the CLTD/CLF/SCL (Cooling Load Temperature Difference / Cooling Load Factor / Solar Cooling Load) method. hvac design calculations excel

Or for heating: GPM = Btu/hr / (500 * ΔT) Store a friction loss vs

Where ΔT is the temperature difference between supply and return air (typically 20°F for cooling). Use INDEX/MATCH or linear interpolation to find the

Velocity (FPM) = CFM / Area (ft²) . Add conditional formatting to highlight if velocity exceeds 1,500 FPM (noise risk) or 2,500 FPM (erosion risk). 4. Water Pipe Sizing (Hydronic Systems) For chilled or hot water systems, use:

=B2/(1.08*20) – assuming B2 holds the sensible heat load. 3. Duct Sizing (Equal Friction Method) Using the equal friction method (e.g., 0.08 to 0.12 in. w.g./100 ft), you can size ducts using a friction chart approximation.