Energy-saving heating and ventilating system and control method thereof

The invention discloses an energy-saving heating and ventilating system and a control method thereof. According to the energy-saving heating and ventilating system and the control method thereof, hot water is conveyed to a heating and ventilating device through a heat exchange water storage tank, a fuel gas heating device and an electric heating device are used for heating a water body for the heat exchange water storage tank, and the usage amount of fuel gas of the fuel gas heating device and the electricity consumption of the electric heating device are detected through a metering module. The method comprises the steps that the electric charge increase rate value and the fuel gas charge increase rate value are generated in real time according to the electricity consumption and the usage amount of the fuel gas in a pricing module; when the electric charge increase rate value is greater than the fuel gas charge increase rate value, the electric heating device is switched on through a control module; and when