Your Questions Answered By The Experts
Q. Do I need radiant barrier if my home is already well insulated?
A. SUMMER
"A radiant barrier system can stop 95 percent of the thermal radiation
across an attic space. If it is not stopped, that radiant energy would
be absorbed by the ceiling insulation and eventually be transferred to
the living space below." "The Solar Collector", Quarterly Newsletter of
the Florida Solar Energy Center
WINTER
"Reflective foil retrofitted to fiberglass insulated buildings is
demonstrably effective in reducing heat loss... Insulation of foil in
uninsulated buildings would show even more pronounced reduction in heat
loss." Northeastern Illinois University, Professor Charles Shabica, May
20, 1986
Q. Is a two sided radiant barrier more effective than a one sided
product?
A. "This study shows, a two sided radiant barrier reduced almost
twice as much heat flow into the home as a one sided radiant barrier
over R.19 insulation." Dennis O'Neal, Texas A&M University, "An
Evaluation of Placement of Radiant Barriers and Their Effectiveness In
Reducing Heat Transfer In Attics"
Q. What is the "R" value of a radiant barrier?
A. "One of the most surprising results obtained in the FSEC tests was
the mutually enhancing effect of RBS's and attic ventilation. When they
measured the "apparent R-value" of ventilated attic systems with and
without radiant barriers, they came up with values of R-68 with the RBS
and R-38 without RBS! ("Apparent R" is calculated from the temperature
difference across the whole attic, from roof surface to ceiling below.)"
Energy Design Update, March 1986, Vol.5, No. 3
