In conjunction with Taisei Corp., Tokyo , and Kurimoto Ltd, Osaka , Rengo has developed lightweight air conditioning duct material. The duct material is made from corrugated board 0.8mm thick laminated with 20 micron aluminum film and is much lighter than traditional duct material, which is made from 0.6mm steel plate. Since corrugated board gives thermal insulation, the duct does not require the insulation usually needed for steel duct. The weight is only 1kg for 1 square meter. Corrugated duct material can be constructed and installed onsite, while steel duct must be assembled in a factory and transported to the site. The new material can be transported in compact fashion.