The Risks of PIR Insulation: Environmental, Health, and Structural Concerns
Polyisocyanurate (PIR) insulation is commonly used in construction, especially in Structural Insulated Panels (SIPs) and timber-frame homes, due to its high thermal resistance and lightweight nature.However, PIR insulation poses several challenges regarding installation, environmental impact, health risks, fire hazards, and long-term structural reliability. Improper installation can further exacerbate these concerns, leading to compromised insulation performance and safety risks.
PIR is derived from petrochemicals, resulting in a high embodied carbon footprint. The production of 1m3 of PIR insulation emits approximately 35-50 kg CO2e/m3 (Jones & Hammond, 2007). This makes PIR less sustainable compared to alternatives like cellulose, recycled glass wool or wood fibre; which have a lower carbon footprint. As efforts to reduce carbon emissions intensify, PIR becomes less favourable for projects prioritizing environmental sustainability (Duffy et al., 2020).
One of the significant drawbacks of PIR is its emission of volatile organic compounds (VOCs), including formaldehyde and other chemicals that can negatively affect indoor air quality. Off-gassing is most pronounced in the initial weeks after installation but can persist long-term (Persily & Gorfain, 2008). These VOCs can cause respiratory issues, eye irritation, and headaches. In well-sealed, energy-efficient buildings, the limited fresh air exchange exacerbates the potential for indoor air quality problems (Hodgson et al., 2002).
PIR insulation presents notable fire hazards, even when treated with fire retardants. During combustion, PIR emits toxic gases such as hydrogen cyanide and carbon monoxide, which can be lethal even at low concentrations (Jones et al., 2015). These risks are particularly concerning in residential or public buildings, where safety standards are paramount. Research has shown that while PIR may meet basic fire performance standards, the toxic fumes it emits can pose severe risks in the event of a fire (Vassart et al., 2018).
Structural Concerns: Delamination in SIPs
The insulation needs to be of good quality & well installed
This can only be achieved through careful detailing & design
These must be thermally broken and correctly installed
To achieve even the basic standard of Building Regulations in the UK, Mechanical Ventilation should be installed to prevent condensation mould & poor air quality – the ‘Heat Recovery’ element of this is a relatively cheap add-on if you are doing this already and will make a very quick return on your money through savings on heating.
Arguably the most difficult aspect to achieve; airtightness needs to be considered from the very beginning of your design process
These key elements are brought together and proven through the PHPP modelling software. Even if you do not wish to build to the full PH standard, employing these principles in your build will lead to a highly energy efficient and comfortable home/building.
Tŷ Eco’s passivhaus UK accreditation
At Tŷ Eco, we are accredited to design and build to Passive House standards. This will help you to save money on your energy bills, with high levels of insulation, airtight building fabric, and MVHR Mechanical Ventilation systems with efficient heat recovery.
