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About the Specification Generator

This Natural Fibre Insulation Specification Generator has been developed by Gusto and Back to Earth for The Alliance for Sustainable Building Products, in collaboration with the BIO-CIRC project.

The online tool provides a range of example building specifications utilising natural fibre insulation (NFI) for roof, wall and floor build-ups. Planned future updates include the addition of 2D drawings and 3D mockups.

For more detailed information and more accurate U-value calculations, please take the specification to your chosen supplier. For a list of NFI manufacturers and suppliers, please see

About Alliance for Sustainable Building Products (ASBP)

The Alliance for Sustainable Building Products (ASBP) is a non-profit, mission driven organisation, with an ever-growing membership alliance of forward-thinking companies and institutions from across the built environment sector.

Launched at the Palace of Westminster in 2011 with 9 founder members, our membership now totals over 125 progressive organisations, including world-renowned research institutions, trade bodies, architectural practices, contractors, and product manufacturers from start-ups and innovators, to market-leading multinational companies.

Find out more and join the ASBP at


During the BIO-CIRC project we investigated the waste bedding sector and the potential reuse of a problematic waste source – polyester duvets, which currently suffer from poor recycling rates and sanitary issues. The waste polyester duvets were ‘refiberised’ to create a feedstock for 3 novel natural and recycled fibre insulation prototypes. Find out more about the project at

The project has been awarded by the Interreg VA Franch (Channel) England programme, which is co-financed by the ERDF. The European Union (ERDF) has funded 80% of the project budget, which amounts to about €500,000 overall (€399,600 from ERDF).

The Channel Manche programme is a Cross Border European Territorial Cooperation (ETC) Programme which aims at supporting the development of the France (Channel) England area in line with the goals of the 2020 Europe strategy to create jobs and smart, sustainable and inclusive growth. All specifications on this website are provided in both English and French language.