Thursday, May 26, 2011

Energy Audit tips: Are radiant barriers worth it?

Attic radiant barriers are a topic of confusion in the building science industry.  They get a decent amount of hype, probably because it is a space-age looking material that is fairly new to the scene.  What is this stuff?  Will it really work?  It makes sense...  Should I spend $2/sq ft to have it installed in my home? (note: I am convinced that over 1/2 of the undue attention paid to radiant barriers has to do with the fact that it is shiny.  People love shiny things.  When I work booths at trade shows, I always make sure to have something shiny on prominent display.  There is no shame in playing down to people's basic instincts.  "oooh...thats so shiny...Lets go look at it!")

Don't spend your money on this.
I'll keep this post short and sweet.  Here is a quote from the Oak Ridge National Labratory, as excerpted from Martin Holladay's attached article: 

“The tests to date have shown that in attics with R-19 insulation, radiant barriers can reduce summer ceiling heat gains by about 16 to 42 percent compared to an attic with the same insulation level and no radiant barrier. These figures are for the average reduction in heat flow through the insulation path. They do not include effects of heat flow through the framing members. … THIS DOES NOT MEAN THAT A 16 TO 42 PERCENT SAVINGS IN UTILITY BILLS CAN BE EXPECTED. Since the ceiling heat gains represent about 15 to 25 percent of the total cooling load on the house, a radiant barrier would be expected to reduce the space cooling portion of summer utility bills by less than 15 to 25 percent. Multiplying this percentage (15 to 25 percent) by the percentage reduction in ceiling heat flow (16 to 42 percent) would result in a 2 to 10 percent reduction in the cooling portion of summer utility bills.”

Perhaps it makes sense in an excessive cooling climate in the right application at the right installed cost (i.e.- cheap).  It certainly does NOT make sense in Climate Zone 5A.  Spend your money on air sealing and insulation.

Here is Martn's article, as found on Green Building Advisor Dot Com. 

Perhaps the worst part about the discussion on radiant barriers?  The Snake Oil factor.  I have been to several homes, all 3 of them senior citizens, where radiant barriers have been sold at exorbitant costs with the promise of unattainable 40% energy savings.  These folks went to a "free" luncheon where they were told to bring their checkbook so they could be pitched the idea and pushed a hard sale.

Second time this week I have beceome disconcerted with unscrupulous contractors/salesman ripping off the elderly.  Where's Dexter when you need him?

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