Polyiso Manufacturers Turn Blind Eye to Problems at Cold Temperatures

When word spread that the chemicals used to make high-performance foam insulation were actually massive contributors to global warming, polyisocyanurate (polyiso) manufacturers were among the first to reformulate. But it turns out that pentane, the new blowing agent, has a problem of its own: a potential 9%–28% drop in R-value at cold outdoor temperatures—just when insulation is most needed. And almost five years after this issue first came to light, polyiso manufacturers are still denying it’s a problem and haven’t taken action to improve performance at extreme temperatures.