INSULATION
Since the release of SANS 10400XA: 2021, an R-value of 3.7 for the insulation layer has become ubiquitous, with the exception of zone 5H( high-humidity coastal). What varies from one insulation material type to another are the reported thermal conductivity( K) values and densities. Therefore, the installed thickness( or depth) of each insulation type is prescribed under SANS-10400-XA: 2021( see https:// tipsasa. co. za / wp-content / uploads / 2022 / 05 / SANS _ 10400-XA _ 2021 _ Ed2 _ Guide-1. pdf).
A key advantage of cellulose fibre insulation, including Thermguard and Eco-Insulation, is that it exits the factory gate with a very low embodied carbon / energy content. Thanks to a low-energy mechanical process of manufacture, the EE of prepared cellulose fibre insulation exiting the factory gate is rated at between 0.94 – 3.3 MJ / kg in the ICE 2 guide as published by BSRIA. This is the lowest in insulation class by a wide margin, as indicated in Table 1. In addition, cellulose fibre insulation offers the lowest in class embodied carbon content per installed unit.
What is cellulose insulation?
In South Africa, popular brands Eco- Insulation and Thermguard are known natural fibre blow-in insulation products. Arising from paper sourced from sustainable timber plantations, cellulose insulation is upcycled from waste-stream paper products, primarily newsprint, which provides a very high recycled material content. Cellulose fibres have a wool-like structure; therefore, they are called paper wool in other countries. To make the cellulose fibre flame-retardant, borax, boric acid, and / or ammonium sulfate are added, typically up to 20 % by mass. This, along with the energy footprint of the manufacturing process, is taken into account in ICE reporting and included in factory gate values for embodied carbon and energy.
Cellulose insulation is used in wall and roof cavities to insulate, draught-proof and reduce free noise. It can be used in both new and existing homes, usually as loose-fill in open roof space installations and increasingly dense packed inside cavities – there are spray-on options also in the market. Like other loose-fill materials, it is blown( pneumatically pumped) onto ceilings, finished wall cavities, and other often inaccessible places.
Net zero in the future
Whilst the operational net energy savings from using different insulation types remain significant on the journey towards net zero operational energy usage, there will be a tailing-off of operational energy savings, making the actual material embodied carbon / energy of singular importance over the building ' s lifecycle.
Another factor to consider is end-of-life. Can the material be re-used? And if it is scheduled to be destroyed, what is the impact of that on the full lifecycle of that building?
What is clear, however, is that ultimately the holy grail will be the material that can be indefinitely recycled and reused, and which can enter the system boundary with a negative net zero footprint. For example, one emerging cellulose material is hemp. Work in this arena is ongoing.
Low energy, low water manufacturing process.
About the contribution
This essay is a precis of R & D work done by the writers for Green Fibre Insulation, a South African company that manufactures and distributes cellulose fibre insulation and compound derivatives in South Africa, including Eco-Insulation and Thermguard. These products comply fully with the requirements of SANS10400-XA: 2021.
Further information about cellulose can be obtained from the manufacturer( https:// gfinsulation. co. za) by emailing: carla @ gfinsulation. co. za or eric @ gfinsulation. co. za for technical queries.
Product is blown into place inside the roof. 66 autumn 2026 | www. tobuild. co. za
References
1
( Ref Dr Craig Jones – https:// circularecology. com / embodied-carbon-footprint-database. html)