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.
=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.
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: hvac design calculations excel
Flow Rate (GPM) = 24 * Q (Tons of Cooling) / ΔT (°F)
Heating, Ventilation, and Air Conditioning (HVAC) design is a numbers-driven discipline. From load estimation to duct sizing and water flow rates, accuracy is paramount. While dedicated software exists (like Carrier HAP or Trane Trace), Microsoft Excel remains an indispensable tool for engineers and technicians. Its transparency, customizability, and accessibility make it ideal for quick checks, iterative designs, and client-approved calculation sheets. Store a friction loss vs
CFM = Sensible Heat Load (Btu/hr) / (1.08 * ΔT)
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. Use INDEX/MATCH or linear interpolation to find the
Or for heating: GPM = Btu/hr / (500 * ΔT)