The problem of computing optimal control strategies for time-scheduled operation of heating, ventilating and air conditioning systems is explored. A two-zone variable air volume heating system consisting of a 4 ton heat pump, a storage tank, water and air flow networks and two environmental zones is considered. The optimization problem that takes into consideration the building operation schedules consisting of night-setback, start-up, occupied modes and energy price discounts is formulated and solved for a given predicted weather profile. Results showing the optimal mass flow rates to the zones, air and water supply temperatures, energy input to the heat pump and the resulting zone temperatures are given.