A warm edge spacer bar is a type of spacer used in double-glazed or triple-glazed windows. It is designed to enhance the energy efficiency and thermal performance of the window unit. The warm edge spacer bar is typically made of materials that have lower thermal conductivity than traditional spacer materials like aluminum. Common materials used in warm edge spacers include thermally optimized plastics, stainless steel, and composite materials. The primary purpose of a warm edge spacer bar is to reduce heat loss and improve the overall insulation of the window. By using materials with lower thermal conductivity, it helps to minimize the transfer of heat between the interior and exterior of the window unit.