PUR vs PIR vs Mineral Wool — Which Cold Room Panel Should You Specify?
PIR is the default for new cold storage: best thermal performance per mm, B-s2,d0 fire class, competitive cost. PUR is legacy — cheaper but weaker fire behaviour. Mineral wool is specified where EI 60–120 fire compartmentation is mandatory, at 30–50% CAPEX premium and 40% thicker walls.
Side-by-side comparison
| Criterion | PIR (Polyisocyanurate) | PUR / Mineral Wool |
|---|---|---|
| Thermal conductivity λ | 0.022 W/m·K | PUR 0.024 / MW 0.037–0.042 |
| Fire class (EN 13501-1) | B-s2,d0 | PUR B/C-s3,d0 / MW A1 |
| Fire integrity EI | EI 15–30 | PUR EI 15 / MW EI 60–120 |
| Panel thickness for U=0.15 | 150 mm | PUR 160 / MW 240–280 mm |
| Density | 38–42 kg/m³ | PUR 38–42 / MW 90–120 kg/m³ |
| Cost per m² (150 mm) | €55–90 | PUR €50–85 / MW €90–140 |
| Ageing (25 y λ retention) | ≥95% | PUR 88–92% / MW 100% if dry |
| Recyclability | Take-back scheme | Both recyclable |
CAPEX
PIR panel supply: €38–65/m² (100 mm) to €75–120/m² (200 mm). PUR is 5–10% cheaper. Mineral wool is 40–70% more expensive at equivalent U-value because 40% extra thickness is required to match PIR.
OPEX
Insulation choice affects electricity via U-value stability over life. PIR retains 95%+ of λ over 25 years. PUR degrades 8–12% over 20 years. Mineral wool is stable if kept dry; wet mineral wool loses 40–60% performance permanently.
Energy efficiency
PIR λ = 0.022 W/m·K. PUR λ = 0.024 W/m·K. Mineral wool λ = 0.037–0.042 W/m·K. To match a 150 mm PIR panel (U ≈ 0.15), a mineral wool panel must be 240–280 mm.
Environmental impact
PIR/PUR use pentane blowing agents (GWP ~5). Mineral wool is inert but higher embodied energy and shipping mass. All three can be recycled through certified panel-take-back schemes.
Maintenance
PIR/PUR: joint gaskets and seal integrity is the main maintenance item. Mineral wool: vapour barrier integrity — a single perforation lets moisture in, degrading performance and inviting corrosion.
Applications
PIR: default for chilled and frozen storage 0 to –30 °C. PUR: budget refits and small commercial cold rooms. Mineral wool: pharma warehouses with EI 60–120 requirements, blast rooms adjacent to fire risk, and any project under strict local fire codes (Scandinavia, France).
PIR (Polyisocyanurate)
- Best thermal performance per mm — thinnest wall
- B-s2,d0 fire class accepted by most insurers
- Stable λ over 25-year design life
- Widely available across EU, GCC and Asia
- Pentane blowing agent — some green-building schemes prefer mineral wool
- Fire behaviour weaker than mineral wool for EI 60+
- Requires certified installer to hit joint airtightness
PUR / Mineral Wool
- Mineral wool: A1 non-combustible, EI 60–120 fire compartments
- PUR: lowest CAPEX for small cold rooms and refits
- Mineral wool: mandatory for pharma GDP fire zones
- Mineral wool: no blowing-agent GWP
- PUR: measurable λ drift over life
- Mineral wool: 40% thicker walls, heavier structure
- Mineral wool: catastrophic performance loss if wet
Decision guidance
Default to PIR for chilled and frozen storage. Upgrade to mineral wool where local fire code demands EI ≥60, in pharma warehouses adjacent to production, and in insurer-driven high-risk installations. Use PUR only for small commercial refits where CAPEX is the binding constraint and fire code allows.
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