A crucial step in the evolution of modern plant agriculture was the development of low-cost, energy-efficient greenhouse structures that provide optimum growing conditions year-round. In 1964, Professor William J. Roberts developed the first air-inflated double-layer polyethylene greenhouse covering system at Cook College, Rutgers University. Air-inflated double-layer polyethylene greenhouse covering systems were quickly and widely adopted throughout the United States and across the world, primarily due to the relatively low installation costs, adequate light transmission, and significant insulating properties. Today, more than half of all the greenhouses worldwide are covered with the air-inflated double-layer polyethylene covering system.