Disclosed is a heating device, including a housing, and an electrothermal film and a fan arranged in the housing, wherein the fan is located at a bottom of the electrothermal film, the fan is provided with an air inlet facing upwards and an air outlet facing forwards, and the housing is provided with a vent hole at a position corresponding to the air outlet.

A sand-based thermal storage apparatus, and a related system and method for heating a building are provided. The apparatus comprises an outer vessel, an inner vessel, a particulate heat storage material, and an electric heater. An annular interwall air space is defined between a wall of the outer vessel and a wall of the inner vessel, and surrounds the inner vessel. The interwall air space is in fluid communication with an outer vessel inlet and an outer vessel outlet. The particulate heat storage material comprises sand and is disposed in the inner vessel interior space and in contact with the inner vessel wall. At least part of the electric heater is embedded in the particulate heat storage material.

A sand-based thermal storage apparatus, and a related system and method for heating a building are provided. The apparatus comprises an outer vessel, an inner vessel, a particulate heat storage material, and an electric heater. An annular interwall air space is defined between a wall of the outer vessel and a wall of the inner vessel, and surrounds the inner vessel. The interwall air space is in fluid communication with an outer vessel inlet and an outer vessel outlet. The particulate heat storage material comprises sand and is disposed in the inner vessel interior space and in contact with the inner vessel wall. At least part of the electric heater is embedded in the particulate heat storage material.