What’s A Radiant Barrier?
By J.R. Bluett
Radiant barriers seems to be a huge deal — Dallas is inundated with advertising about the energy and monetary savings that can be had if you just pony up the cash to install a radiant barrier. But what’s the big deal, and why haven’t my Toolmonger friends in the Midwest ever heard of it?
According to the U.S. Department of Energy, a radiant barrier is a highly reflective material designed to stop heat from passing from one open space into another. In other words, a radiant barrier is to heat radiation what a mirror is to visible light. This heat mirror can keep your attic cooler, or your house warmer.
Radiant barriers are less effective at keeping in winter heating energy than at keeping out the summer sun, and because they’re a whole-house solution, they’ll have the greatest impact if the whole house is cooled. Traditional insulation may still provide a better solution for keeping your house comfortable, but the radiant barrier is a good tool for the sunny South.
Photo of house-wrap application of radiant barrier posted on Flickr by Giles Douglas.
Radiant Barrier Fact Sheet [ORNL.gov] (Oak Ridge National Laboratory = U.S. Department of Energy)
Reflective Insulation [Energy Star]
Toolmonger Photo Pool [Flickr]
August 7th, 2008 at 1:34 pm
I installed a foam board insulation with a radiant barrier under the siding on my house. It was 1-1/2″ foam covered with a perforated foil. It was comparable in price as just the plain foam and it was easier to install so I bought it. My house is warmer in winter and cooler in summer now, but I would like to know if the foil really makes a measurable difference over just the foam.
August 7th, 2008 at 4:18 pm
I would like to know how it does in moist enviroments
like the west coast does it compare to things like tyvek house wrap
August 7th, 2008 at 5:32 pm
I recently sold a 2000 sq/ft 2 story in the Austin area with no radiant barrier and my electricity bill ran about $380 per month with 1 AC unit. The house was bought new and 5 years old when I sold it
I moved into a brand new built 1 story 3000 sq/ft home that has the radiant barrier and 2 AC units. Been here 3 years and the electricity bill is still $160 per month.
The barrier does work.
August 7th, 2008 at 5:33 pm
The numbers I quoted are in the dead of summer.
August 7th, 2008 at 10:40 pm
Most of the advertising you hear is for the spray-on radiant barrier paint which at best will reflect about 75% of the heat. Unfortunately, there are some less than honest contractors who will dilute the paint with water since it is very expensive. Radiant Barrier Attic Foil will reflect 97% of the radiant heat and you can install it yourself with a staple gun and utility knife.
Get a buddy and get it done! It’s a fairly inexpensive project that can have significant results.
For complete info, pictures and instructions visit: http://www.AtticFoil.com
August 8th, 2008 at 1:30 am
We used “Astrofoil-E” on a home we built last year, under a tile roof. After we had installed it, there was a significant drop in temperature. It went in easy enough (just staple it to the rafters, and metal-tape the overlap), and really wasn’t all that expensive.
August 8th, 2008 at 5:07 am
The reason your Midwest friends haven’t heard of it is tat they don’t need it near as badly as y’all do in the South.
We’ll average 70 or more days per year of below freezing weather, but only 10 days or so where the barrier against radiated heat (sunlight) is needed.
On other words, it isn’t cost effective.
August 8th, 2008 at 8:57 am
Which is about as effective as simply using some white paint.
Spray on radiant barriers do not work. The Journal of Light Construction just had a bit about this (note: this link will NOT work after August 2008 unless you’re a subscriber: http://www.jlconline.com/cgi-bin/jlconline.storefront/EN/UserTemplate/82?c=890065e559a1af419c2202d7216b912a )
Reputable organizations that don’t have an interest in your wallet (like southface.org and fsec.ucf.edu) do say that in warm weather climates (the US SE and SW) a properly installed radiant barrier can save you ~10% on your AC costs (not overall energy costs) during the summer.
Note that FSEC also discusses their testing of radiant barrier paint and its utter uselessness.
August 10th, 2008 at 4:55 pm
Radiant Barriers are a very economical way to conserve energy, prolong life of a/c life, save money and easy to install. We distribute the highest quality MicroFoil, MicroLt,Igloo, MicroVent factory direct as we are a totally green company who believes warehousing only adds costs and hurts the environment more. Please see us at http://www.GreenInsulationProducts.com or call 877 904 8424 for more info.
August 11th, 2008 at 12:52 pm
Radiant barriers definitely work in the south and do pretty well up north as well. The average savings is about 17% and that was some tests that were done in Tennessee.
@Rob - To answer your questions about moisture and humidity, if you are installing a Radiant Barrier in a hot humid place, it is of utmost importance that you use a perforated radiant barrier. Even though it is perforated, it can still be used in place of tyvek as it will still act as an air draft barrier, but it wont create an unintentional vapor barrier.
side note:
We installed a perforated radiant barrier in our attic and the bills this summer are noticeably lower (aprox $50-$70). We used http://www.raflect.com
December 18th, 2008 at 4:22 pm
I’ve worked with Radiant Barrier Specialists in the Dallas area. They use both a foil and a spray-on radiant barrier. Supposedly, the foil works most efficiently, knocking away something like 97% of radiant heat.
December 25th, 2008 at 8:21 pm
[...] With a radiant heat system, a radiant barrier will reflect the heat back into the home, heating your home much more efficiently. Click to see:->Radiant Barier & Energy Savers What’s A Radiant Barrier? [...]
May 17th, 2009 at 1:32 pm
All of our customers who have gotten back to us have reported excellent result in energy conservation and lower energy bills since installing their radiant barrier attic insulation.
June 1st, 2009 at 11:58 am
On our recent install on an outbuilding of ours we installed a similar product that works as a radiant and vapor barrier. This worked great inside our pre-existing steel building to lower the temperature in the hot summer months and removed a moisture problem we were having. We purchase our insulation from http://www.buyreflectiveinsulation.com. Many similar products out there but this A1V product had adhesive strips that made installation a snap.
September 11th, 2009 at 3:59 pm
I think it’s great that most of the posts on this site are companies tring to get link credit to their radiant barrier sites. The links on this site are nofollows so who knows how much benefit they give.
Radiant Barrier is great.
October 6th, 2009 at 10:38 am
The fact of the matter is most homes compared to today’s current standard have inadequate insulation. All types of insulation should be installed. When you go in your attic to put in a radiant barrier, make sure you add more fiberglass insulation whether in batt form or blown-in.