Zone controls give you more power to control how your house is heated and cooled. An HVAC system without zone controls provides general heating and cooling to the house whenever it is turned on. Each room vent in the house sends out conditioned air, regardless of whether the rooms require it or not. You’re familiar with this system because you probably have one like it. On a cold day in winter, when you turn the furnace on for warmth, all the rooms in the house receive heat blown through the ventilation system.
This is convenient—but you can probably already tell why it isn’t always for the best. Would you want an electrical system where flipping a single light switch turns on every light in the house? Of course not, that’s wasteful. Do you need to accept the same type of operation from your HVAC system? Not when you have zone controls.