Building roof structure

Claim 1

A roof structure for a building having first and second end walls and opposed side walls, the roof structure providing reduced ari conditioning load for the building, comprising; spaced apart horizontal prulins supported at their ends by building exterior end walls, each purlin having a top edge and a bottom edge; roof sheathing affixed to the top edges of said purlins; ceiling sheathing affixed to the bottom edges of said purlins providing horizontal plenums between the roof and ceiling sheathing and between adjacent purlins, the horizontal plenums thereby extending the length and width of the building roof, the maximum height of the plenums being equal the height of the purlins; means at the first end wall for providing ventilation into each of the plenums formed between said purlins; a fan means includes; a fan housing mounted on the second end wall having an intake communication with said plenums at the second end wall; an exhaust opening in said fan housing; and a fan supported in the fan housing which, when energized, withdraws air from the fan housing and thereby from the plenums and discharges air out said end wall exhaust opening.