AFICA welcomes any contributions on this subject, through the Secretary or President – see CONTACT US.
The reason AFICA has been formed is because there is a misconception of how foil insulation actually functions, and is a benefit to society.
Foil insulations are capable of functioning for thermal performance, waterproofing (i.e. sarking), and vapour control.
General guidance for foil insulations for optimal thermal performance requires the existence of adjoining airspaces, the width of the airspace, the air speed and allowance for variable dust accumulation on upward facing surfaces. These factors are accounted for in the insulation standards AS/NZS 4859.1-2018 and 4859.2-2018.
What is missing in the suite of Insulation standards, is the lack of interconnection of all the standards to be validated by any real house thermal testing in the Australian context. Errors and failings in standards and national NCC regulations are amplified by the lack of any discussion regarding:
- Building Thermal Dynamics in totality – e.g. bulk insulations are tested only for conducted heat, not representative of hot climate radiant heat levels
- The impact of The Law of Diminishing Returns – increasing R-values produce rapidly diminishing benefit, a highly complex topic.
The absence of any commentary on this topic in either 4859.2 or 3999 renders these standards close to useless, because the common held belief “more insulation is better” is completely false.
- 3999 has other multiple failings, one glaring omission is no commentary or warning about the impact on installed “Total R-value’ of uninsulated areas in ceiling against heat flow up losses.
Another failing is Clause 1.4.3, which classifies segmented foil products ( i.e non-roll form) as bulk insulations, ‘for the purposes of this standard’.
No foil insulation product can be exclusively classified as bulk insulation, because that is a scientific impossibility.
The following insulation standards govern material description as well as installation of differing insulation materials.
AS/NZS 4859.1-2018 “General Criteria & Technical Provisions”, and AS/NZS 4859.2-2018 “Design” – calculation for ‘Total R-value’ (also known as ‘installed R-value’)
AS 3999-2015 “Bulk thermal insulation – Installation”
AS/NZS 4200.1-2017 “Pliable Building Membranes: Materials”, AS/NZS 4200.2-2016 “Pliable Building Membranes: Installation”