A design process is developed for an OCCUPANCY RELATED VENTILATION CONTROL SYSTEM (ORVCS) in a new entertainment centre in Sha-tin, Hong Kong. The aim is to reduce the cost of space cooling. Little work appears to have been done in using ORVCS in conjunction with space cooling up to the present time. Thedesign process includes (a) the selection of a control parameter to modulate the fresh air supply rate (b) assumptions about the occupancy load profile and (c) estimation of the possible energy savings. It is concluded that for certain zones of the building the annual energy savings due to use of an ORVCS could be as high as 29% and the pay-back time about 9 months.