So you are doing your due diligence by researching whether or not radiant barrier is a scam is true. Radiant barriers installed in existing homes have generated a lot of confusion and controversy. As energy auditors we know that too often energy saving claims have become grossly bloated from 20% of air conditioning bills to 20% of your entire electricity bill, which is quite different. Consider this, if heat gain into a home with good insulation is only 15% from an attic, how can a radiant barrier reduce the energy bill by a minimum of 25%? It’s impossible!
A homeowner today should also be aware that there is no one energy saving upgrade that will create a high performing home in terms of comfort, lower air conditioning bills and air quality. Homeowners should therefore be considerate of alternative recommendations such as duct sealing and air conditioning tune-ups to work in conjunction with a radiant barrier. The Department of Energy has performed studies and written articles on radiant barrier foil and has concluded it works by reducing attic temperatures and thus reduces heat gain into a home. What is the problem then? We will cover that later but first I’d like to go over the different types of radiant barriers on the market.
Radiant barrier paint, radiant barrier chips and radiant barrier foil are the three types of radiant barriers. We do not support the installation of radiant barrier chips or radiant barrier paint. Radiant barrier paint can be diluted in the field with water and will lose its effectiveness when applied. I’ve seen many houses where the radiant paint looks more like gray paint rather than a reflective paint, which is a sign of dilution. Radiant barrier paints also has lower performance standards with higher emittance values and lower reflectance values than traditional radiant barrier foils. Radiant barrier chips are not recommended because installers usually do not install them with enough density to cover the entire surface area of the attic and they can be easily moved. Besides the radiant barrier paint and chips, we do support the use of radiant barrier foils.
The radiant barrier foil comes either in single or double sided; breathable with ventilation holes or it may not have any ventilation; or has a foam core with some insulation value to it. By itself, a radiant barrier has no insulation value because it reflects radiant heat from radiation, unlike insulation that slows down the transfer of heat through conduction. Radiant barriers should also be installed along the roof trusses whenever possible compared to laying along the attic floor.
How Much Heat Comes From The Attic?
Surprisingly, not as much as you would think. According to APS and SRP studies only 14% - 20% of your utility bill is driven by heat gain from the attic, most of it comes from windows. I can also validate these findings from my personal experience modeling hundreds of homes in the Phoenix area under the APS energy audit program and SRP energy audit program. On a side note, there is up to $1,000 in APS rebates and SRP rebates available for home energy upgrades. Visit the APS Energy Audit Program and SRP Energy Audit Program for more information.
If There Is No Radiant Barrier Scam, Then Why Do Most Fail?
The problem just like a driving a Prius with a hole in the gas tank - is how it is installed and a lack of understanding of what homes it will have an effect on and what homes it will do nothing for. Most radiant barriers are sold by a sales consultant who is not a certified energy consultant and will sell radiant barriers to every home they go to and over promise on their performance. A comprehensive energy audit should be performed with a blower door test and by a BPI Certified auditor to test and identify the real causes and solutions to reduce energy bills and eliminate hot and cold rooms. In an attic with R-38 insulation, the heat gain into the house is small and is approximately 80% conduction and 20% radiation. The radiant barrier is going after that 20% of heat gain which may not be the most cost effective option. There are certain cases where a radiant barrier would be a good choice for your home, but Green ID will not sell or install radiant barriers where it is not needed or better options exist.
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9/25/2011 11:08:17 am
This is a great post.
Excellent feedback Scott, too often energy saving products are recommended with no real understanding of how it effects the home. For example, in some cases solar attic fans have been shown to suck conditioned air from the house up to the attic which creates carbon monoxide and health and safety hazards as well as wasting energy. Homeowners need to be made aware of these dangers for their own families' protection.
3/5/2013 12:35:21 am
In colder (winter) climates when the heat is turned on, can a radiant barrier reflect heat back into a home if installed on the attic floor joists?
9/15/2013 09:56:05 am
Hi Greg, in cold climates a radiant barrier can reflect the heat back in the attic however avoid at all costs a radiant barrier installed on the attic floor (unless the insulation is along the roof slope and the attic is conditioned space). You want to avoid radiant barrier attic floor because once it gets dusty, and it always gets dusty in unconditioned attics, it looses its effectiveness.
6/27/2015 11:32:15 am
Hi, I live in an 8 year old house in south ga. I was considering installing a radiant barrier. I have measure the temperature in my attic at 145+. I have ridge vents but the air does not move at all in the summer. Would this be of any benefit?
7/24/2018 03:14:10 am
great blog post....complete guidance mentioned in it. thank you for sharing with us.
paul a pipkin
9/23/2018 01:22:31 pm
I believe that a well insulated attic that has been properly sealed, chalking vents, pipes, gaps, etc, would be a more effective way of keeping the home cooler/warmer. That being said, if you apply a foil radiant barrier to the rafters and seal the seams with foil tape, you could lower summer time attic temps and reflect winter time heat loss back to the house. From what I have read and experienced with radiant barriers, proper installation is key and ONLY if the home is in a HOT CLIMATE. Keep in mind that metal roofs will work better with the radiant barrier and that the attic should have proper ventilation. Asphalt shingles will gain more heat from radiant barriers and will have a shorter life span. If applied to the bottom side of rafters, it creates and air space. which is what manufactures recommends with installation of radiant barriers. It is still expensive and as I said, your money will be better spent properly sealing the attic gaps, vents and pipes, flues etc, and adding more insulation
12/10/2021 09:07:54 am
I like that this post reminded us that when considering to have a solar attic fan installed, it is important for us to ensure that it is installed by certified professionals. It makes sense for us to ensure that it is installed by a professional to prevent any accidents or hiccups. I wil l definitely keep this information in mind for future references.
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