Rigid mineral wool can be an excellent substitute for polystyrene, owing to its moisture repellency and insect resistance.
Polystyrene, in both extruded and expanded forms, is very widely used as rigid insulation in North America and worldwide. In below-grade applications, owing to its good insulation value, superb moisture resistance, strength, performance, and affordability, polystyrene dominates the market.
But a chemical that’s added to polystyrene to provide fire resistance has recently raised significant concerns. Indeed, the European Union may be on the verge of significantly restricting the use of this chemical—HBCD. Given other environmental concerns about polystyrene, this latest development raises the question of whether this insulation material belongs in green buildings at all.