Fiberglass insulation is designed to counter conductive heat transfer by absorbing and holding onto heat. In winter, the heated air from your furnace moves upwards, being more buoyant than colder air. Your fiberglass insulation in your attic is helpful in slowing the heat’s movement. The heat does not migrate downward, so there’s no heat for the fiberglass insulation to absorb, making it ineffective. It is also important to note that fiberglass insulation does not air seal the surface it is insulating, which means that any gaps in the surface (e.g. from utility penetrations in your subfloor) will allow cold air from your vented crawl space to migrate upward to your living space.

Radiant Barrier can cause moisture issues if not installed properly or the wrong material is used. When installing a Radiant Barrier in the attic, a "perforated" product that meets or exceeds ASTM standards should be used.

In a humid climate, it is imperative that the attic floor utility penetrations be properly air sealed with foam spray or similar material. This will not only greatly increase the energy efficiency of the home, but will prevent cold, conditioned air from the living space to mingle with hot, humid air in the attic.

Installing a non-perforated Radiant Barrier may lead to moisture or condensation issues.

Moisture and condensation will not be concerns, however, with properly installed and perforated Radiant Barrier combined with effective air sealing.

Radiant Barrier is much more effective against summer heat than fiberglass insulation. Fiberglass works like sponge, absorbing and trying to hold on to heat. But, like a sponge, it can become saturated…in this case, with heat. Once it is saturated, the remaining heat will pass through as if it wasn’t there.

Radiant Barrier does not absorb but reflects heat and is also a barrier that does not allow radiant energy to convert into additional radiant heat. TRB’s Radiant Barrier blocks 95% of radiant heat, the primary heat in your attic in summer, from impacting your living space which will provide for optimal increases in home comfort and energy efficiency.

There are several contributing factors to determine a savings percentage: age / condition of your HVAC system, proper attic ventilation, seals around your doors and windows etc. If those are adequate or better, the energy savings resulting from a Radiant Barrier insulation is typically 25%-45% on heating and cooling costs.