One key factor affecting the energy efficiency of a window or door is the spacer system that is located inside the sealed insulating glass unit. The spacer system is the material that separates the panes of glass. Many materials can be used to formulate a spacer system, but by far one of the most effective for improving energy efficiency is the MPG (Maximum Performance Glass) spacer system offered by Sprouse. All materials used in the system are non-metal – thereby lowering energy conduction rates and reducing condensation problems. The MPG spacer system is used in both the MPG and MPG Plus™ glass packages.