YELLOW SUBMARINE, Part Two

Ring's detention chamber for blue meanies worked fine at first, but a problem developed because he was too successful at catching them! Their meanness led to lots of fights, noise, and general unpleasantness, so he needed to modify his detention chamber. In his second design, he split the chamber into three parts, with barbed wire partitions of course! The entire chamber should still have $40$ square meters of area. What dimensions of the chamber minimize the amount of barbed wire?