The present invention aims to radiate heat efficiently from the inside of an equipment housing, with a simple structure. First and second through air passageways are formed at the sides of first to third equipment housings and the second through air passageway communicates with a recess air passageway to supply air from the first through air passageway into the first to third equipment housings, discharge the exhaust from the first equipment housing directly out of the equipment through a second window portion, and lead the exhaust from the second and third equipment housings into the second through air passageway through the second window portion and the recess air passageway and discharge it out of the equipment.