I want some basic guidlines/check list for estimating heat loads and duct layouts. Working on project for Mall where only Atrium portion is to be aircon. My major concerned is with the duct layout.The atrium height from the ground is 50' having skylight.The building is G+2 floors having attrium in centre hence confused in positioning of the supply and return air duct. Also considering High cfm equipments for this application. Appreciate any recommendation or suggestion for the same.