Rigid wall shelters are used throughout the world for shipping, living quarters, and housing for electronic systems and are energy inefficient. While investigating energy-efficient technologies for rigid wall shelters the discovery was made to insulate the outside of the shelter rather than the inside. Space is often limited inside of the shelter. The invention of an external, re-deployable insulation system was developed. The present invention is an insulating system composed of three main components. The first component is multiple, purpose cut flexible envelopes filled with insulating materials (which creates a panel). The second component is multiple insulating strips that cover the joint between the panels. The final component is a weatherproof outer covering that protects the entire system from the elements.