PROTO-HVAC™ models ventilation systems and calculate flows, pressures and temperatures through control dampers, fans, and ducts for system balance and optimized performance in existing systems or for contemplated changes. Utility engineers can quickly evaluate the performance of heating, ventilation, and air conditioning systems to assess the impact of plant changes, demonstrate conformance for plant licensing, and minimize costs for maintenance and operations. PROTO-HVAC simplifies the task by integrating all HVAC system variables into a comprehensive computer model. The user can simultaneously model or examine every control damper's type and position, fan's performance, and heat exchanger's performance to precisely balance air flows, pressures, and temperatures.