The sewn-through sewing method is the most commonly used joining method for the manufacturing of 3D nonwoven textile assemblies. A major disadvantage to the sewn-through sewing method is that the 3D assemblies are compressed by the sewing threads along the stitch lines. These compression points are also commonly referred to as ‘cold spots’ in functional clothing. These points are present all along the stitch line and force the entrapped air present inside the insulation material to leave its structure. In this way, they act as a bridge to facilitate heat transfer. There is a general compromise on product functionality where joining with the sewn-through sewing method takes place and is taken as a byproduct of current sewing technology. A machine-based technological solution has been invented which is named as 'Spacer Stitching' technology at ITM, TU Dresden. With the new innovative technology, the 3D nonwoven assemblies are successfully joined with the sewn-through method, without creating conventional 'Cold Spots'. The results are promising and are validated by various skin models by increasing the thermal resistance of non-woven assemblies. Within the framework of ongoing DFG funding, the technology is further improved. Along with the insulation of functional garments, the Spacer Stitching technology is also relevant for industrial insulation products, medical textiles, spacer fabrics, and composites.