Infrared radiant barrier

Just curious, I am installing a radiant barrier in my attic and am trying to see the progress to see if they work. I installed this part yesterday and took an image with my infrared. Is this image of any use or does the reflective nature of the foil make it impossible to get a usefull reading. It does seem cooler up there with the part over the garage finished. And no I dont offer infrared as a service to clients untill I can afford to take the level1 & 2.



A radiant heat barrier makes a real difference when done fully and correctly, your pic shows apparent temps without any compensation ( I assume) but and I risk being roasted for this lol, I bet it’s close or at least gives a ball park idea of what’s happening which is due to the radiant barrier working

All you are seeing with the camera is reflected energy off the barrier. Not sure what you trying to prove here. A centrally located thermometer may help, but you would need a base line before you installed the barrier.

But the energy coming through the roof deck has been blocked ( for the sake of conversation, I am not going into technicalities) and reflected back out so it is doing something…totally agree with you about everything else, and his thermogram isn’t “useful” as it is IMHO other than to show a radiant barrier does work in theory

I’m just seeing if a thermal camera is useful for judging to see if these actually work or if the information the camera is giving off is false due to it being a reflective material. It’s a slight pain in the butt to install by yourself but if it helps cool my attic then I’ll keep on trucking. I know a little thermometer would have been ideal but I ruined that by already starting.

Did you read the instructions on how to install it?

Didn’t they cover the relationship between emission and reflection for non-transmissive surfaces in the Infrared Certified training? About 99% of the incident radiation that your imager receives from the foil is reflected. The point of having a Low-E surface is that it has very little ability to emit radiation, it is however a most fantastic reflector of radiation and a great thermal conductor too.

Of course but I have vaulted ceilings and lugging a 50lb roll of foil around up there isn’t the easiest thing to do.

Howard, there are hundreds of things that you can calculate utilizing a thermal imaging camera. And what you are asking is one of them.

Unfortunately there are a bucket load of camera owners here at think the expense of equipment and training is a bunch of malarkey.

Did you know that in level II training you walk away with the ability to determine how many watts of electricity is being consumed by a lightbulb hidden underneath a 12 quart aluminum pot!?

Let’s try to wrap our minds around this for a minute and see where it takes us.

#1 we are trying to analyze the effectiveness of a radiant barrier.

The key here is “radiant”.
We’re not measuring how hot the barrier is with relation to other things in the attic we want to know how we can remove the amount of radiant heat that is affecting the total heat in the attic. After all that’s why we’re putting it in there.

So, what is a radiant barrier? Is something that blocks radiant heat (not conduction and not convection). It doesn’t matter if the radiant barrier is 100°. What matters is that what it is constructed of does not “radiate”.

So of you simply take your temperature readings as indicated below you will see that the truss members that are shadowed by the radiant barrier have a significant lower temperature than those exposed to the roof deck.

Divide this into each other and it will give you a percentage.

Note, if you put a substance on the radiant barrier that has a high emissivity (something that you can measure accurately) you are going to find the temperature of that radiant barrier is as close in temperature to that of the roof deck.

Conduction + convection + radiation = total heat load in the attic.

Because there is a huge amount of radiation affect going on in an attic space when you address the radiation amount of heat load significantly drops.

What happens if your roof is covered by a tree shadow?

Answer: you wasted your money on a radiant barrier.


Thank you for taking the time to reply David, I do look forward to the day when I can afford this class aka convince the wife that this will be beneficial. I find this stuff fascinating and can’t wait to learn more about it.

Not a problem! That was a well constructed question.

Bradley-a thermometer will not work in this application. A thermometer does not measure radiant heat until it is absorbed by something and change to a convection load.

The thermal imaging camera is the tool to utilize in evaluating radiant heat conditions, but you must know how to use it and interpret the results.

Mike-the thermogram is “useful”. His point of focus is just in the wrong place. If you look again at the scan you can actually see a “shadow” (so to speak) associated with the radiant barrier.


Is that a “shadow” from the radiant heat or is the rafter thats attached to the sheathing just hotter because its in direct contact with it and the other isnt?

What I was getting at was whether the radiant barrier was actually doing something or not. I would guess that a thermometer set up, with periodic readings data would give you an idea. But only if you had something to compare it to before the installation (with similar outside conditions).

I’ve never tried to do a thermal assessment on a radiant barrier, so still learning what can be achieved with it. I also think that those shadow lines on the truss webs would be more of a reflective signature, correct?

No. The truss is not that reflective. It would be more defused looking rather than spectacular anyway.

You need a very sharp angle of view for wood to become reflective, but it will.

A thermometer is best used for measurement of fluids (air & water).
The right tool, for the right job.