Thermally insulating packaging

Thermally insulating packaging 100 comprises an arrangement of cellulosic paper layers sewn together with a thread 130. The layers include one or several inner paper layers 110 between first and second outer paper layers 120, and each outer layer has a greater areal density than each inner layer. Preferably, each outer layer also has a greater volumetric mass density than each inner layer. The stitching may go along at least two opposed edges of the packaging. The inner layer may be pleated, and may have an inner paper assembly provided between the first and second outer layers, comprising the pleated inner layer between first and second facing inner paper layers adjacent opposed faces of the pleated inner paper layer. A method of manufacturing the packaging comprises forming the arrangement of cellulosic paper layers and sewing them together with a thread.