The heating, ventilation, and air conditioning (HVAC) system is arguably the most complex system installed in a building and is responsible for a substantial component of the total building energy use. Maintaining optimal temperature and air circulation are the basis of a comfortable indoor environment[1]. This role is played by HVAC (Heating, ventilation and air conditioning) systems. The heat load calculations along with the duct design for a HVAC system installed in a multistorey residential building is calculated and analyzed to maintain a desired temperature based on outer environmental temperature. The duct design is analyzed which create an impact on system performance. The layout of a multistorey residential building is made by using Autodesk REVIT software. A complete air conditioning system was designed along with ducts and VAV system to control the indoor environment conditions like temperature, relative humidity, air movement, etc. Based on the obtained Heat Load Calculations CFM & T.R values were found for each spaces and ducting design was done for all the spaces by considering the quantity of CFM to be supplied. A suitable air handling unit (AHU) is selected based on the CFM value for multi storey residential building. With this the capacity of equipment was estimated and selected for the installation.