Does Reflectix keep heat in or out?
They do a nice job of keeping out heat (and light) when in place. Does reflective insulation keep heat in? Unlike mass insulation, reflective insulation is able to keep heat in and reflect heat away. Mass insulation material like fiberglass and foam merely slow down the transfer of heat; they do not reflect heat away, nor do they keep heat in. Reflective insulation has the ability to control the transfer of radiant heat.