a detailed guide for selecting components in an HVAC (Heating, Ventilation, and Air Conditioning) system, covering AHU (Air Handling Unit), FCU (Fan Coil Unit), coils, and fans. It lists the key factors to consider for each component: for AHUs, factors include airflow rate, external static pressure (ESP), cooling/heating capacity, filter requirements, and construction material. For FCUs, considerations include capacity, airflow, type, static pressure, noise level, and control methods. The section on coils covers type, capacity, fin spacing, tube material, and entering/leaving air and water temperatures. Lastly, the fan selection focuses on air volume, static pressure, type, efficiency, noise level, and speed control. This guide is essential for properly sizing and selecting HVAC components to ensure efficient system performance.