PROBLEM TO BE SOLVED: To solve the problem that conventionally, various methods or structures have been proposed to uniform the temperature within a greenhouse, that is to uniform the temperature in a vertical direction (upper part of the interior of a greenhouse and area around the plants in shelf cultivation), and a simple structure as shown in Figs. 6 to 8 is thought to be effective for improvement of temperature uniformity in a horizontal direction, however, any consideration is not taken regarding the sending of warm or cool air to around the plants in shelf cultivation.SOLUTION: The air ventilation system according to the present invention includes in an upper part of the interior of the greenhouse: first circulation fans arranged on the same horizontal plane annually in a direction toward each of both sides； and second circulation fans located in the vicinity of the horizontal plane, the second circulation fans being oriented toward plants within the greenhouse. The air ventilation system uses shelf cultivation for promoting the sending of warm or cool air to around the plants, to thereby alleviate stuffiness of air, to improve planting in a good environment, to grow strong and healthy plants with short internodes and less unproductive growth, to promote photosynthesis, to secure economical efficiency, and to reduce fuel consumption.【課題】 従来、ハウス内の温度の均一化、即ち、上下方向(上部と棚栽培により植物近傍との部位)において、温度の均一化を図るために、種々な方法、又は構造が提案されている。その中で、簡便な構造として、図６～図８に示すように、水平方向には有効であると考えられる。しかし、棚栽培により植物近傍への暖冷気の送風に関しては、何らの配慮がされていないと考えられる。【解決手段】 本発明は、ハウスの上部において、各第１循環扇を、同じ水平面で、かつ両妻面方向に環状に配備し、水平面の近傍に配備した各第２循環扇を、ハウスの植物の方向に向かって配備するハウス栽培の空気循環システムであり、棚栽培により植物近傍への暖冷気の送風を図ることで、ムレ軽減と、快適環境での植栽を図り、徒長が少なく、節間の短い、丈夫で健康的な作物生成と、光合成の促進と、経済性の確保を図り、かつ燃費の節約を図る。【選択図】 図３
