Air density decreases with altitude. Velocity pressure is based on density.
| Component | Qty | PD per Unit (in.w.g.) | Total PD | | :--- | :--- | :--- | :--- | | | | | | | 50 ft rigid duct | 1 | 0.10 | 0.10 | | (4) 90° elbows | 4 | 0.07 | 0.28 | | Supply diffuser | 2 | 0.08 | 0.16 | | Return Side | | | | | 30 ft flexible duct | 1 | 0.15 | 0.15 | | Return grille | 1 | 0.06 | 0.06 | | MERV 8 filter | 1 | 0.18 | 0.18 | | Subtotals | | | | | Supply Total | | | 0.54 | | Return Total | | | 0.39 | | Calculated ESP | | | 0.93 in.w.g. | | +15% Safety Factor | | | 1.07 in.w.g. | esp calculation hvac excel sheet
: The final calculated ESP is then compared against the Blower Performance Data provided by the manufacturer. If the calculated ESP exceeds the blower's rated capacity at the required CFM (Cubic Feet per Minute), the system will underperform, leading to poor air distribution and potential equipment failure. Air density decreases with altitude
The fluorescent lights of the 14th floor HVAC design room hummed with a frequency that only the sleep-deprived could truly appreciate. Outside, the Chicago rain slapped against the glass, but inside, the only storm was happening on Marcus’s monitor. | | +15% Safety Factor | | | 1
By building your Excel sheet with these modules and formulas, you move beyond a simple spreadsheet into a professional engineering tool capable of HVAC system commissioning and verification.