Design Four-Zone Office Ductwork

I need a complete duct layout from a clean slate for an open-plan office that will be divided into four separate meeting zones beneath a standard 2 ft × 2 ft lay-in ceiling grid. There is no existing HVAC to tie into, so the design must include the full run—from supply and return mains through to appropriately sized diffusers and grilles—while respecting the grid and keeping service access simple for future maintenance. Please base your sizing on typical conference-room occupancy and ventilation rates, indicate CFM requirements per zone, and show all branch sizes, fittings, and balancing devices on the drawing. I will provide the reflected ceiling plan in DWG; you can return the finished layout in AutoCAD (model and PDF sheets) along with a short calculation summary and a basic equipment schedule so my mechanical contractor can price it immediately. If you have any questions about clearance around beams or preferred diffuser styles, let me know early so we can lock those decisions in and keep the submittal process smooth.