You may choose down as a natural alternative, but welfare concerns and the fact that it can’t get wet rule it out for many, so where do you turn? Apparel company Paka hopes it will be towards Pakafill, a new insulation made from alpaca fibre. It’s early days for this patent-pending insulation, but the fact that it passed a field test at 17,913 feet altitude in the Andes Mountains is certainly a convincing debut. Outdoor brands should form an orderly queue.