Light transmitting building panel

In a greenhouse having a structural framework, opposite side walls and opposite end walls erected on said framework, and a roof structure spanning between said opposite side walls and supported on said framework;

• the combination including:
• said roof structure comprising a plurality of edge overlapped panels spanning between said opposite side walls and each comprising,
• a flat central sheet having a first face and opposite thereto a second face,
• lower and upper corrugated sheets confronting, respectively, said first face and said second face of said flat central sheet and each being secured to said flat central sheet along contiguous portions thereof, said lower and upper corrugated sheets cooperating with said flat sheet to provide, respectively, a set of inner cells presented interiorly of said greenhouse and a set of outer cells presented exteriorly of said greenhouse,
• the upper corrugated sheet being laterally offset relative to the lower corrugated sheet such that each outer cell is presented intermediate of adjacent inner cells, and
• said flat central sheet and lower upper corrugated sheets each being formed from light transmitting glass fiber reinforced plastic;
• and
• A gas recirculating system comprising:
• a heat reservoir having a reservoir inlet conduit and a reservoir outlet conduit;
• outlet duct means extending between and communicating with the cells of one said set at one end of the panels of said roof structure and with said reservoir inlet conduit;
• inlet duct means extending between and communicating with said reservoir outlet conduit and with the cells of said one said set at the opposite end of the panels of said roof structure;
• and
• fan means for recirculating gas through said system and the cells of said one said set.