The non-renewable (fossil) primary energy requirements for the production of insulation materials (grey energy) differ considerably. E.g. less than 100 kWh/m³ is used for the production of materials requiring little processing such as wood shavings or cellulose fibres, but 1300 kWh/m³ is needed for the manufacture of foam glass, PU (polyurethane) or XPS. When calculating the energy payback for insulating materials, the expenditure for their production is compared to the saving of primary energy resulting from their insulation effect. Therefore the energy payback is dependent on the original situation, insulation thickness, insulation type, heating method, energy source and climate. As a rule, the energy payback of insulating materials is less than two years in the middle European climate. For organic insulating materials like hemp or cellulose the energy amortisation period can be cut to just a few months. Even the energetically least favourable combination of costly insulating materials and high insulation thickness generally leads to an energy amortisation period of less than five years as several studies have shown.
Read more arguments against misunderstandings regarding thermal insulation here.