To realize the full performance potential of the new generation of ground based telescopes, whether optical or IR, enclosure seeing control and telescope temperature control must be optimized. While the techniques for optimizing seeing are well known, EOS' IceStorm Enclosures, specifically developed for interferometric applications, introduced a number of novel physical implementations of these known techniques. A 9.5m prototype IceStorm enclosure was assembled and extensively tested in 2002, including independent testing of thermal performance. Four enclosures have since been completed, one of which was installed at the EOS Space Center on Mt Stromlo, Australia in 2003. Design principles for the IceStorm enclosure and thermal test results are described, and the application of these principles to larger enclosures is discussed.