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Mineral wool
Melted rock or glass spun into A1 batts — the default non-combustible insulation of codes.
Overall 69 🧽Polyurethane foam
The low-λ organic foam of fridges and buildings — excellent insulation, a fire design problem unless PIR and coverings are honest.
Overall 46 📦Vacuum insulated panel
A sealed vacuum sandwich — λ around 0.004–0.008 W/m·K until the envelope leaks.
Overall 44 🕯️Phase-change material
Latent-heat packets that flatten temperature swings — not a substitute for λ insulation, a complement.
Overall 36