Duct System Design Calculation Excel Template

Duct system design is a critical phase in HVAC engineering that ensures conditioned air is delivered efficiently, quietly, and uniformly throughout a building. Poorly designed ducts lead to excessive static pressure, fan energy waste, uneven temperatures, noise, and compromised indoor air quality. The Excel template operationalizes key design workflows—including velocity selection based on application type (e.g., 700–1,200 fpm for main supply ducts), friction loss calculation using the Darcy-Weisbach or Hazen-Williams equations (adapted for air), and dynamic loss coefficients for fittings—by embedding lookup tables, conditional logic, and iterative solvers (e.g., Goal Seek for target static pressure). Modern templates often incorporate features such as automatic duct sizing per equal-friction or static regain methods, color-coded velocity/pressure alerts, summary dashboards with fan power estimation (using fan laws), and export-ready reports compliant with LEED or local energy codes. Integration with BIM workflows (via CSV/DXF export) and sensitivity analysis capabilities (e.g., 'what-if' scenarios for duct insulation or leakage rates) further enhance its utility in collaborative design environments.