Ventilation and air-conditioning structure and ventilation and air-conditioning method

A ventilation air conditioning structure comprising:

• a room structure body including wall portions partitioning an interior and an exterior of a room inside a building, wherein at least one of the wall portions is an outer wall portion that is in contact with the outdoors, the outer wall portion having a first ventilation opening formed in a vicinity of one of adjacent wall portions and a second ventilation opening formed in a vicinity of another of the adjacent wall portions;
• an air conditioner including a room interior unit that is disposed inside the room structure body, the air conditioner being capable of sending air, taken in from an air intake opening, in a direction of a wall portion facing the outer wall portion via a refrigerant piping that connects the room interior unit and a room exterior unit;
• and
• an external-air conditioner that is disposed at an outdoor side of the outer wall portion, the external-air conditioner including:
• a heat exchanger provided in a refrigerant circuit of the air conditioner via a branched pipe that is branched from the refrigerant piping;
• and
• a casing that houses the heat exchanger,
• wherein a first opening portion opening is formed in the casing in a downward direction,
• wherein a second opening portion opening is formed in the casing at a back portion towards an outer wall portion direction, and
• wherein the second opening portion is communicative with either the first ventilation opening or the second ventilation opening.