Glossary · Insulation & windows
Radiant barrier
Also called: radiant barriers · radiant barrier foil · reflective insulation · reflective foil · foil insulation · radiant foil
A shiny foil layer, usually in attics, that reflects the sun's radiant heat; it helps most in hot, sunny climates.
What it means
A radiant barrier reflects radiant heat instead of absorbing it, but it doesn't slow conducted heat the way insulation does. It needs an air space next to its shiny side to work, and dust on that side reduces its effect.
Why it matters in an audit
It does little for heating bills, so in colder climates compare it against simply adding insulation, and check your rebate rules, since some programs exclude it.