We provide detailed airside engineering calculations to determine the external static pressure (ESP) and airflow requirements of HVAC systems, ensuring proper fan selection and reliable system performance. Our analysis evaluates pressure losses across ductwork, fittings, dampers, filters, coils, air terminals, and other system components, accounting for the actual configuration and operating conditions. The resulting calculations support optimized air distribution, energy-efficient fan operation, accurate equipment selection, and coordinated HVAC design documentation in accordance with applicable ASHRAE and SMACNA standards.